Background:This study aims to predict the extraction difficulty of mandibular third molars based on panoramic images using transfer learning while employing super-resolution(SR)technology to enhance the feasibility an...Background:This study aims to predict the extraction difficulty of mandibular third molars based on panoramic images using transfer learning while employing super-resolution(SR)technology to enhance the feasibility and validity of the prediction.Methods:We reviewed a total of 608 preoperative mandibular third molar panoramic radiographs from two medical facilities:the First Affiliated Hospital of Zhengzhou University(n=509;456 in the training set and 53 in the test set)and the Henan Provincial Dental Hospital(n=99 in the validation set).We conducted a deep-transfer learning network on high-resolution(HR)panoramic radiographs to improve the longitudinal resolution of the images and obtained the SR images.Subsequently,we constructed models named Model-HR and Model-SR using high-dimensional quantitative features extracted through the Least Absolute Shrinkage and Selection Operator method.The models’performances were evaluated using the receiver operating characteristic curve(ROC).To assess the reliability of the model,we compared the results from the test set with those of three dentists.Results:Model-SR outperformed Model-HR(area under the curve(AUC):0.779,sensitivity:85.5%,specificity:60.9%,and accuracy:79.8%vs.AUC:0.753,sensitivity:73.7%,specificity:73.9%,and accuracy:73.7%)in predicting the difficulty of extracting mandibular third molars.Both Model-HR(AUC=0.821,95%CI 0.687–0.956)and Model-SR(AUC=0.963,95%CI 0.921–0.999)demonstrated superior performance compared to expert dentists(highest AUC=0.799,95%CI 0.671–0.927).Conclusions:Model-SR yielded superior predictive performance in determining the difficulty of extracting mandibular third molars when compared with Model-HR and expert dentists’visual assessments.展开更多
[Objectives] To shorten the time of removal of the bone embedded mandibular third molar,reduce the complications of tooth extraction,and explore a surgery method of resistance-free removal of the mandibular third mola...[Objectives] To shorten the time of removal of the bone embedded mandibular third molar,reduce the complications of tooth extraction,and explore a surgery method of resistance-free removal of the mandibular third molar. [Methods] A total of 50 patients with bone embedded mandibular third molar needing to be removed were selected. A 45° elevation turbine and a long tungsten steel drill were used to remove the mesial,buccal,and distal resistances. When necessary,tongue side and root resistance was removed,and the third molar was removed when there was basically no resistance around it. The removal time was recorded,followed up for 10 d,and the postoperative reaction was observed. [Results] The bone embedded mandibular third molars were removed for all patients within 15 min,and there was no serious postoperative reaction,all patients showed high satisfaction. [Conclusions]The method of resistance-free removal of the bone embedded mandibular third molar can significantly shorten the removal time,reduce the fear of patients,and ease pain of patients.展开更多
Teeth affect not only oral problems but also facial morphology.In China,there are few reports about the influence of the third molars on the craniofacial morphology of Han youths.Using in vivo imaging software,3D reco...Teeth affect not only oral problems but also facial morphology.In China,there are few reports about the influence of the third molars on the craniofacial morphology of Han youths.Using in vivo imaging software,3D reconstruction of craniofacial CTs were performed on 32 Chinese Han youths without mandibular third molars and 25 Chinese Han youth with full mandibular third molars.The morphology of their mandible and mandibular tissue was measured to identify differences.Among the morphological characteristics of hard tissues,except for∠ANB,people with a full eruption of the mandibular third molars had statistically significantly larger angle indicators than people without the eruption of the third molars.The soft tissue indicators also showed statistically significant discrepancies in terms of morphological facial height,mouth to gnathion distance,lip height,and mouth breadth.The most influential index for mandibular third molars was length of symphysis,followed by the four indicators of soft tissue and mandible length and height.Morphology facial height,mouth to gnathion distance,lip height,and height of symphysis were moderately correlated.The experimental results show that among Han youth in North China,the third molar eruption has a widespread influence on mandibular morphology,especially in angle,length,and height indicators.It also has a certain influence on maxillofacial soft tissue morphology.These results can be applied to future clinical risk assessment of the wisdom teeth and forensic personal identification of the cranial and maxillofacial region.展开更多
Aims & Objectives: This study was performed to evaluate the incidence, risk factors (age, sex, infection, radiographic difficulty of the extraction, tobacco use) contributing to the development of dry socket and c...Aims & Objectives: This study was performed to evaluate the incidence, risk factors (age, sex, infection, radiographic difficulty of the extraction, tobacco use) contributing to the development of dry socket and clinical features following surgical removal of impacted mandibular third molar. Materials and Methods: The study included 63 patients during period of September 2009 to September 2011 in the age group of 18 to 53 years with impacted mandibular third molars all of which were surgically removed under local anesthesia by the same operator. Following surgery all patients received a single dose of 4 mg corticosteroid intravenously and similar prescriptions for analgesics, antibiotics and postoperative instructions. All patients were reviewed at 3rd and 7th day postoperatively. Results: In this study incidence of dry socket was 6.3%. We also noticed onset of symptom mostly appeared within 48 hours. Postoperatively pain, bare bone and halitosis were the most significant clinical feature at 3rd postoperative day and pain, empty socket and bare bone were most significant clinical feature at 7th postoperative day. Variables like right 3rd molar impaction, patients mean age between 19 - 32 years, female, preoperative infection, radiographically difficult impaction and habitual tobacco users showed a higher incidence of dry socket formation. Conclusion: Incidence of dry socket formation is multifactorial and therefore, there is need to evaluate all factors, with special attentions in handling these patients to reduce the incidence of dry socket formation.展开更多
Background: The over-ambitious use of surgical drills for almost every case of third molar impaction is on the increase in most established oral surgery centers. The purpose of this study was to assess and compare the...Background: The over-ambitious use of surgical drills for almost every case of third molar impaction is on the increase in most established oral surgery centers. The purpose of this study was to assess and compare the severity of post operative symptoms of swelling and pain that accompany the use of surgical drill in the buccal guttering technique and the non application of drill in an alveolar expansion technique. Methods: Consecutive patients with bilateral impacted lower third molars not associated with pericoronitis were included in the study, a total of 10 patients were included in the study. Extraction of both impacted third molars was done consecutively on the same day under local anaesthesia. Post operative morbidities that were assessed clinically are swelling and pain. Results: A total of 10 patients, 70% were females and males were 30%. Age range was 27 - 35 yrs.Out of the eight patients that had the two different techniques, 7 preferred the use of the alveolar expansion technique in which drill was not used. There were statistically significant differences in swellings between these two techniques, (p 0.01). Conclusions: To avoid excessive swelling and pain from over-ambitious cut-ting of soft tissues and drilling of bone, alveolar expansion technique should be considered first in pa-tients with less dense bone.展开更多
Aims and Objectives: The aim of the study was to compare the effect of complete and partial wound closures on postoperative sequelae and complications after surgical removal of impacted mandibular third molars. Patien...Aims and Objectives: The aim of the study was to compare the effect of complete and partial wound closures on postoperative sequelae and complications after surgical removal of impacted mandibular third molars. Patients and Methods: One hundred and twenty patients who required 121 surgical extractions of mandibular impacted third molars were included in the study. Patients were randomly divided into 2 groups based on wound closure after surgery. In group 1 (complete wound closure, n1 = 60) patients had their extraction sockets completely closed by mucosal flap while in group 2 (partial wound closure, n2 = 60) patients had their extraction sockets partially closed. Data collected included maximum inter-incisal distance (MID) and facial width which were recorded both preoperatively and postoperatively. What also recorded were postoperative pain intensity and postoperative complications. Results: There were 50 (41.7%) males and 70 (58.3%) females (male to female ratio of 1:1.4);age range was 18-40 years and the mean was 26 ± 10 years. The mean ages of patients in both groups showed no significant difference (group 1 = 26.5 ± 7.2;group 2 = 27.1 ± 8.1). The pain was maximal at the first postoperative day review and it gradually reduced in intensity towards the preoperative values for both groups. The pain perceptionsin patients in group 2 were however significantly lower than those of group 1 on days 1 and 3 but not statistically different on day 7. The mean difference in the postoperative and preoperative MID was greatest on the 1st postoperative day and gradually became smaller on the subsequent review days. Comparison of this mean difference between the 2 groups however showed a significant difference in the 2 groups only on day 7. Maximal swelling was noted in both groups on the third postoperative day. A comparison of the mean facial width between the two groups showed no statistically significant difference on all the review days. The postoperative complication rate was 5% in both groups. Conclusions: The results of the study indicate that there was a comparative reduction in postoperative sequelae namely pain and trismus after impacted mandibular third molar surgery when a partial wound closure technique was done. However, there was no significant difference in the postoperative complication rate between the two groups.展开更多
Double teeth refer to two teeth that are totally or partially joined by dentin and maybe their pulps. These developmental anomalies may be the result of either gemination or fusion. This is a case of a 15-year-old Ind...Double teeth refer to two teeth that are totally or partially joined by dentin and maybe their pulps. These developmental anomalies may be the result of either gemination or fusion. This is a case of a 15-year-old Indo-Trinidadian male who presented with the fusion of a mandibular third molar with a distomolar as an incidental finding. The patient had his general dental care provided by a paediatric dentist and was referred to an oral and maxillofacial radiologist, orthodontist, and oral surgeon for consultation. A Cone-beam CT was taken to supplement the plain film periapical and orthopantomogram radiographs. It showed the three-dimensional orientation of the double molar and the extent of joining. This is the first case of fusion of a mandibular third molar to a distomolar being reported in the Caribbean.展开更多
Osteoradionecrosis(ORN),a pathological condition characterized by a nonvital bone occurring in the site of radiation injury,is one of the significant risks following extraction of highly impacted third molar teeth in ...Osteoradionecrosis(ORN),a pathological condition characterized by a nonvital bone occurring in the site of radiation injury,is one of the significant risks following extraction of highly impacted third molar teeth in patients treated with head&neck radiotherapy for oral cancer.Therefore,the surgery’s meticulous planning is essential to avoid such complications.This case report describes a 63-year-old male patient diagnosed with an impacted lower third molar(tooth#38)with concurrent basal cell carcinoma of the right ear and squamous cell carcinoma of the right vocal cord treated with radiotherapy.Taking into account the patient’s health status,a minimally invasive osteotomy and a corono-radicular separation procedure were performed.This procedure allowed us to reduce the risk of mandibular ORN.Three years later,the healing was complete,and the situation was stable.展开更多
BACKGROUND Extraction of impacted third molars often leads to severe complications caused by damage to the inferior alveolar nerve(IAN).AIM To proposes a method for the partial grinding of an impacted mandibular third...BACKGROUND Extraction of impacted third molars often leads to severe complications caused by damage to the inferior alveolar nerve(IAN).AIM To proposes a method for the partial grinding of an impacted mandibular third molar(IMM3)near the IAN to prevent IAN injury during IMM3 extraction.METHODS Between January 1996 and March 2022,25 patients with IMM3 roots near the IAN were enrolled.The first stage of the operation consisted of grinding a major part of the IMM3 crown with a high-speed turbine dental drill to achieve sufficient space between the mandibular second molar and IMM3.After 6 months,when the root tips were observed to be away from the IAN on X-ray examination,the remaining part of the IMM3 was completely removed.RESULTS All IMM3s were extracted easily without symptoms of IAN injury after extraction.CONCLUSION Partial IMM3 grinding may be a good alternative treatment option to avoid IAN injury in high-risk cases.展开更多
Middle-mesial canals in mandibular molars are present in the population depending on age, sex and ethnicity. However, limited literature alludes to its prevalence. Troughing procedures may enhance identification, clea...Middle-mesial canals in mandibular molars are present in the population depending on age, sex and ethnicity. However, limited literature alludes to its prevalence. Troughing procedures may enhance identification, cleaning and shaping. This case report expresses the recognition and management of middle-mesial canal in a mandibular second molar of 24 years old Hispanic-Latino male.展开更多
BACKGROUND Most physicians consider molars with chronic apical periodontitis(CAP)lesions as contraindications for immediate implant placement.At the patient’s request,we perform immediate implant placement of the man...BACKGROUND Most physicians consider molars with chronic apical periodontitis(CAP)lesions as contraindications for immediate implant placement.At the patient’s request,we perform immediate implant placement of the mandibular molars with CAP in clinical practice.AIM To retrospectively analyze and compare the 5-year outcomes of immediate implant placement of the mandibular molars with CAP and those without obvious inflammation.METHODS The clinical data of patients with immediate implant placement of the mandibular molars in the Department of Oral and Maxillofacial Surgery,the Affiliated Hospital of Qingdao University,from June 2015 to June 2017 were collected.The patients were divided into CAP(n=52)and no-CAP(n=45)groups.Changes in bone mineral density and bone mass around implants were analyzed 5 years after implant restoration.RESULTS At 5 years after implantation,the peri-implant bone mineral density was 528.2±78.8 Hounsfield unit(HU)in the CAP group and 562.6±82.9 HU in the no-CAP group(P=0.126).Marginal bone resorption around implants did not differ significantly between the two groups,including buccal(P=0.268)or lingual(P=0.526)resorption in the vertical direction or buccal(P=0.428)or lingual(P=0.560)resorption in the horizontal direction.Changes in the peri-implant jump space did not differ significantly between the two groups,including the buccal(P=0.247)or lingual(P=0.604)space in the vertical direction or buccal(P=0.527)or lingual(P=0.707)space in the horizontal direction.The gray value of cone-beam computed tomography measured using Image J software can reflect the bone mineral density.In the CAP area,the gray values of the bone tissue immediately and 5 years after implant placement differed significantly from those of the surrounding bone tissue(P<0.01).CONCLUSION The results of this study suggest that immediate implant placement of the mandibular molars with CAP can achieve satisfactory 5-year clinical results,without significant differences in the complications,survival rate,or bone tissue condition from the no-CAP mandibular molars.展开更多
BACKGROUND The relation between orthodontic treatment and temporomandibular disorders(TMDs)is under debate;the management of TMD during orthodontic treatment has always been a challenge.If TMD symptoms occur during or...BACKGROUND The relation between orthodontic treatment and temporomandibular disorders(TMDs)is under debate;the management of TMD during orthodontic treatment has always been a challenge.If TMD symptoms occur during orthodontic treatment,an immediate pause of orthodontic adjustments is recommended;the treatment can resume when the symptoms are managed and stabilized.CASE SUMMARY This case report presents a patient(26-year-old,female)with angle class I,skeletal class II and TMDs.The treatment was a hybrid of clear aligners,fixed appliances and temporary anchorage devices(TADs).After 3 mo resting and treatment on her TMD,the patient’s TMD symptom alleviated,but her anterior occlusion displayed deep overbite.Therefore,the fixed appliances with TAD were used to correct the anterior deep-bite and level maxillary and mandibular deep curves.After the levelling,the patient showed dual bite with centric relation and maximum intercuspation discrepancy on her occlusion.After careful examination of temporomandibular joints(TMJ)position,the stable bite splint and Invisible Mandibular Advancement appliance were used to reconstruct her occlusion.Eventually,the improved facial appearance and relatively stable occlusion were achieved.The 1-year follow-up records showed there was no obvious change in TMJ morphology,and her occlusion was stable.CONCLUSION TMD screening and monitoring is of great clinical importance in the TMD susceptible patients.Hybrid treatment with clear aligners and fixed appliances and TADs is an effective treatment modality for the complex cases.展开更多
The aim of this study was to investigate the physiological foramen diameter, shape and distance between physiological and anatomical apex of maxillary and mandibular first and second molars. Accurate knowledge of the ...The aim of this study was to investigate the physiological foramen diameter, shape and distance between physiological and anatomical apex of maxillary and mandibular first and second molars. Accurate knowledge of the physiological foramina morphology; thus, inherent mechanical shaping technical hindrances, is decisive when taking the corresponding root canal final preparation decision. The morphological dimensions of a total of 1 727 physiological foramina were investigated by means of micro-computed tomography. Mean narrow and wide(to a high number, oval) diameters of the physiological foramen were 0.24,0.22 and 0.33 mm and 0.33, 0.31 and 0.42 mm in mesiobuccal(MB), distobuccal(DB) and palatal(P) roots in maxillary first molars; 0.24, 0.22 and 0.33 mm and 0.41, 0.33 and 0.44 in MB, DB, and P roots in maxillary second molars. Mandibular first molars showed mean narrow and wide diameters of 0.24 and 0.30 mm and of 0.39 and 0.46 mm in mesial(M) and distal(D)roots; second mandibular molars showed 0.25 and 0.31 mm and 0.47 mm in M and D roots. The mean distance between the physiological foramina and anatomical apex was 0.82, 0.81 and 1.02 mm and 0.54, 0.43 and 0.63 mm in MB, DB and P roots of the maxillary first and second molars, respectively. A mean distance of 0.95 mm(M) and 1.05 mm(D) in the first and0.78 mm(M) and 0.81 mm(D) in the second mandibular molars was observed. Based on the results obtained, assumable recommendations for final preparation size of the physiological foramen were calculated. However, when taking into consideration, the resulting standard deviations of marginal errors must be cautiously considered when taking a final decision in clinical endodontic treatment.展开更多
The aims of the study were to investigate the incidence of C-shaped root canal systems in mandibular second molars in a native Chinese population using radiography and clinical examination under microscope and to comp...The aims of the study were to investigate the incidence of C-shaped root canal systems in mandibular second molars in a native Chinese population using radiography and clinical examination under microscope and to compare the relative efficacies of these methods.For the recognition of C-shaped root canal system,1 146 mandibular second molars were selected and examined.Teeth with C-shaped canal systems were categorized by using the radiographic classification criteria and the modified Melton's method.C-shaped canals were identified in 397(34.64%) mandibular second molars by radiography(type I,31.23%;type II,38.29%;type III,30.48%).Clinical examination showed that 449(39.18%) cases exhibited C-shaped canal systems(C1,22.94%;C2,48.11%;C3a,15.59%;C3b,13.36%).As for the result of the radiographic and clinical combined examination,C-shaped root canals were found in 473(41.27%) mandibular second molars(C1,21.78%;C2,45.67%;C3a,16.70%;C3b,15.86%).The incidence of C-shaped root canal diagnosed by radiographic method was statistically different from that by clinical examination and the combined examination(P,0.05).The study indicated a high incidence of C-shaped canal system in a Chinese population.The combination of microscopic and radiographic examination is an effective method in identifying the C-shaped root canal system.展开更多
The role of third molars in the oral cavity has been extensively studied over the years. Literature includes numerous diagnostic and treatment alternatives regarding the third molars. However, an issue that has not be...The role of third molars in the oral cavity has been extensively studied over the years. Literature includes numerous diagnostic and treatment alternatives regarding the third molars. However, an issue that has not been discussed at the same level is their involvement in orthodontic therapy. The aim of this study is to present a review of the contemporary literature regarding the most broadly discussed aspects of the multifactorial role of third molars in orthodontics and which are of general dental interest too.展开更多
Considering the adverse effects of nonimpacted third molars(N-M3s)on the periodontal health of adjacent second molars(M2s),the removal of N-M3s may be beneficial to the periodontal health of their neighbors.This study...Considering the adverse effects of nonimpacted third molars(N-M3s)on the periodontal health of adjacent second molars(M2s),the removal of N-M3s may be beneficial to the periodontal health of their neighbors.This study aimed to investigate the clinical,immunological,and microbiological changes of the periodontal condition around M2s following removal of neighboring N-M3s across a 6-month period.Subjects with at least one quadrant containing an intact first molar(M1),M2,and N-M3 were screened and those who met the inclusion criteria and decided to receive N-M3 extraction were recruited in the following investigation.M2 periodontal condition was interrogated before M3 extraction(baseline)and at 3 and 6 months postoperatively.Improvements in clinical periodontal indexes of M2s in response to their adjacent N-M3 removal,along with changes in inflammatory biomarkers among gingival crevicular fluid(GCF)and the composition of subgingival plaque collected from the distal sites of the M2s of the targeted quadrant were parallelly analyzed.Complete data of 26 tooth extraction patients across the follow-up period were successfully obtained and subsequently applied for statistical analysis.Compared to the baseline,the periodontal condition of M2s was significantly changed 6 months after N-M3 removal;specifically,the probing depth of M2s significantly reduced(P<0.001),the matrix metalloproteinase(MMP)-8 concentration involved in GCF significantly decreased(P=0.025),and the abundance of the pathogenic genera unidentified Prevotellaceae and Streptococcus significantly decreased(P<0.001 and P=0.009,respectively).We concluded that N-M3 removal was associated with superior clinical indexes,decreased GCF inflammatory biomarkers,and reduced pathogenic microbiome distribution within the subgingival plaque.Although the retention or removal of N-M3s continues to be controversial,our findings provide additional evidence that medical decisions should be made as early as possible or at least before the neighboring teeth are irretrievably damaged.展开更多
Surgical extraction of the third molar is the most commonly performed surgical procedure in the clinical practice of oral surgery.Third molar surgery is warranted when there is inadequate space for eruption,malpositio...Surgical extraction of the third molar is the most commonly performed surgical procedure in the clinical practice of oral surgery.Third molar surgery is warranted when there is inadequate space for eruption,malpositioning,or risk for cyst or odontogenic tumor formation.Preoperative assessment should include a detailed morphologic analysis of the third molar and its relationship to adjacent structures and surrounding tissues.Due to developments in medical engineering technology,computed tomography(CT)now plays a critical role in providing the clear images required for adequate assessment prior to third molar surgery.Removal of the maxillary third molar is associated with a risk for maxillary sinus perforation,whereas removal of the mandibular third molar can put patients at risk for a neurosensory deficit from damage to the lingual nerve or inferior alveolar nerve.Multiple factors,including demographic,anatomic,and treatment-related factors,influence the incidence of nerve injury during or following removal of the third molar.CT assessment of the third molar prior to surgery can identify some of these risk factors,such as the absence of cortication between themandibular third molar and the inferior alveolar canal,prior to surgery to reduce the risk for nerve damage.This topic highlight presents an overview of the clinical significance of CT assessment in third molar surgery.展开更多
Extraction of the lower third molar is one of the most common procedures performed in oral surgery. In general, impacted tooth extraction involves sectioning the tooth’s crown and roots. In order to divide the impact...Extraction of the lower third molar is one of the most common procedures performed in oral surgery. In general, impacted tooth extraction involves sectioning the tooth’s crown and roots. In order to divide the impacted tooth so that it can be extracted, high-speed air turbine drills are frequently used. However, complications related to air turbine drills may occur. In this report, we propose an alternative tooth sectioning method that obviates the need for air turbine drill use by using a low-speed straight handpiece and carbide bur. A 21-year-old female patient presented to the institute’s dental hospital complaining of symptoms localized to the left lower third molar tooth that were suggestive of impaction. After physical examination, tooth extraction of the impacted left lower third molar was proposed and the patient consented to the procedure. The crown was divided using a conventional straight low-speed handpiece and carbide bur. This carbide bur can easily cut through the enamel of crown. On post-operative day number five, suture was removed and the wound was extremely clear. This technique could minimise intra-operative time and reduce the morbidity associated with air turbine drill assisted lower third molar extraction.展开更多
The estimation of chronologic age based on the stages of third-molar development was evaluated by using the eight stages (A–H) method of Demirjian and the third-molar development was compared, in terms of sex and age...The estimation of chronologic age based on the stages of third-molar development was evaluated by using the eight stages (A–H) method of Demirjian and the third-molar development was compared, in terms of sex and age, with results of previous studies. The samples consisted of 291 orthopantomograms from young Chinese subjects of known chronologic age and sex (including 139 males with a mean age of 14.67±3.62 y and 152 females with a mean age of 14.85±3.70 y). Statistical analysis was performed by employing the Mann-Whitney U-test and the t-test. Regression analysis was conducted to obtain regression formulas for calculating dental age from the chronologic age. Our results showed statistically significant differences (P<0.05) in third-molar development between males and females, at the calcification stages D, E and H. And a strong correlation was found between age and third-molar development in both males (r2=0.65) and females (r2=0.61). New equations (Age=8.76+1.32 Development stage) for estimating chronologic age were derived. It is concluded that third-molar genesis took place earlier in males than in females. The use of third molars as a developmental marker is appropriate in young adults of Central China. The formula obtained in the present study can be used as a guide for estimation of dental maturity and a standard for age estimation for young adults of Central China.展开更多
This paper reported a case of fusion between an impacted third molar and a supernumerary tooth, in which a surgical intervention was carried out, with the objective of removing the dental elements. The panoramic radio...This paper reported a case of fusion between an impacted third molar and a supernumerary tooth, in which a surgical intervention was carried out, with the objective of removing the dental elements. The panoramic radiography was complemented by the Donovan's radiographic technique; but because of the proximity of the dental element to the mandibular ramus, it was not possible to have a final fusion diagnosis. Hence, the Cone-Beam Computed Tomography―which provides precise threedimensional information―was used to determinate the fusion diagnosis and also to help in the surgical planning. In this case report we observed that the periapical, occlusal and panoramic were not able to show details which could only be examined through the cone-beam computed tomography.展开更多
基金supported by the National Natural Science Foundation of China(U1904145)the Joint Funds for the Innovation of Science and Technology of Fujian province(2019Y9128).
文摘Background:This study aims to predict the extraction difficulty of mandibular third molars based on panoramic images using transfer learning while employing super-resolution(SR)technology to enhance the feasibility and validity of the prediction.Methods:We reviewed a total of 608 preoperative mandibular third molar panoramic radiographs from two medical facilities:the First Affiliated Hospital of Zhengzhou University(n=509;456 in the training set and 53 in the test set)and the Henan Provincial Dental Hospital(n=99 in the validation set).We conducted a deep-transfer learning network on high-resolution(HR)panoramic radiographs to improve the longitudinal resolution of the images and obtained the SR images.Subsequently,we constructed models named Model-HR and Model-SR using high-dimensional quantitative features extracted through the Least Absolute Shrinkage and Selection Operator method.The models’performances were evaluated using the receiver operating characteristic curve(ROC).To assess the reliability of the model,we compared the results from the test set with those of three dentists.Results:Model-SR outperformed Model-HR(area under the curve(AUC):0.779,sensitivity:85.5%,specificity:60.9%,and accuracy:79.8%vs.AUC:0.753,sensitivity:73.7%,specificity:73.9%,and accuracy:73.7%)in predicting the difficulty of extracting mandibular third molars.Both Model-HR(AUC=0.821,95%CI 0.687–0.956)and Model-SR(AUC=0.963,95%CI 0.921–0.999)demonstrated superior performance compared to expert dentists(highest AUC=0.799,95%CI 0.671–0.927).Conclusions:Model-SR yielded superior predictive performance in determining the difficulty of extracting mandibular third molars when compared with Model-HR and expert dentists’visual assessments.
基金Supported by the People's Livelihood Science and Technology Program of Qingdao City(15-9-2-73-nsh)
文摘[Objectives] To shorten the time of removal of the bone embedded mandibular third molar,reduce the complications of tooth extraction,and explore a surgery method of resistance-free removal of the mandibular third molar. [Methods] A total of 50 patients with bone embedded mandibular third molar needing to be removed were selected. A 45° elevation turbine and a long tungsten steel drill were used to remove the mesial,buccal,and distal resistances. When necessary,tongue side and root resistance was removed,and the third molar was removed when there was basically no resistance around it. The removal time was recorded,followed up for 10 d,and the postoperative reaction was observed. [Results] The bone embedded mandibular third molars were removed for all patients within 15 min,and there was no serious postoperative reaction,all patients showed high satisfaction. [Conclusions]The method of resistance-free removal of the bone embedded mandibular third molar can significantly shorten the removal time,reduce the fear of patients,and ease pain of patients.
基金supported by Biological Anthropology Innovation Team Project of JZMU(Grant No.JYLJ201702)Liaoning Distinguished Professor Project(Grant No.LNTP20183501&LNTP201418701)。
文摘Teeth affect not only oral problems but also facial morphology.In China,there are few reports about the influence of the third molars on the craniofacial morphology of Han youths.Using in vivo imaging software,3D reconstruction of craniofacial CTs were performed on 32 Chinese Han youths without mandibular third molars and 25 Chinese Han youth with full mandibular third molars.The morphology of their mandible and mandibular tissue was measured to identify differences.Among the morphological characteristics of hard tissues,except for∠ANB,people with a full eruption of the mandibular third molars had statistically significantly larger angle indicators than people without the eruption of the third molars.The soft tissue indicators also showed statistically significant discrepancies in terms of morphological facial height,mouth to gnathion distance,lip height,and mouth breadth.The most influential index for mandibular third molars was length of symphysis,followed by the four indicators of soft tissue and mandible length and height.Morphology facial height,mouth to gnathion distance,lip height,and height of symphysis were moderately correlated.The experimental results show that among Han youth in North China,the third molar eruption has a widespread influence on mandibular morphology,especially in angle,length,and height indicators.It also has a certain influence on maxillofacial soft tissue morphology.These results can be applied to future clinical risk assessment of the wisdom teeth and forensic personal identification of the cranial and maxillofacial region.
文摘Aims & Objectives: This study was performed to evaluate the incidence, risk factors (age, sex, infection, radiographic difficulty of the extraction, tobacco use) contributing to the development of dry socket and clinical features following surgical removal of impacted mandibular third molar. Materials and Methods: The study included 63 patients during period of September 2009 to September 2011 in the age group of 18 to 53 years with impacted mandibular third molars all of which were surgically removed under local anesthesia by the same operator. Following surgery all patients received a single dose of 4 mg corticosteroid intravenously and similar prescriptions for analgesics, antibiotics and postoperative instructions. All patients were reviewed at 3rd and 7th day postoperatively. Results: In this study incidence of dry socket was 6.3%. We also noticed onset of symptom mostly appeared within 48 hours. Postoperatively pain, bare bone and halitosis were the most significant clinical feature at 3rd postoperative day and pain, empty socket and bare bone were most significant clinical feature at 7th postoperative day. Variables like right 3rd molar impaction, patients mean age between 19 - 32 years, female, preoperative infection, radiographically difficult impaction and habitual tobacco users showed a higher incidence of dry socket formation. Conclusion: Incidence of dry socket formation is multifactorial and therefore, there is need to evaluate all factors, with special attentions in handling these patients to reduce the incidence of dry socket formation.
文摘Background: The over-ambitious use of surgical drills for almost every case of third molar impaction is on the increase in most established oral surgery centers. The purpose of this study was to assess and compare the severity of post operative symptoms of swelling and pain that accompany the use of surgical drill in the buccal guttering technique and the non application of drill in an alveolar expansion technique. Methods: Consecutive patients with bilateral impacted lower third molars not associated with pericoronitis were included in the study, a total of 10 patients were included in the study. Extraction of both impacted third molars was done consecutively on the same day under local anaesthesia. Post operative morbidities that were assessed clinically are swelling and pain. Results: A total of 10 patients, 70% were females and males were 30%. Age range was 27 - 35 yrs.Out of the eight patients that had the two different techniques, 7 preferred the use of the alveolar expansion technique in which drill was not used. There were statistically significant differences in swellings between these two techniques, (p 0.01). Conclusions: To avoid excessive swelling and pain from over-ambitious cut-ting of soft tissues and drilling of bone, alveolar expansion technique should be considered first in pa-tients with less dense bone.
文摘Aims and Objectives: The aim of the study was to compare the effect of complete and partial wound closures on postoperative sequelae and complications after surgical removal of impacted mandibular third molars. Patients and Methods: One hundred and twenty patients who required 121 surgical extractions of mandibular impacted third molars were included in the study. Patients were randomly divided into 2 groups based on wound closure after surgery. In group 1 (complete wound closure, n1 = 60) patients had their extraction sockets completely closed by mucosal flap while in group 2 (partial wound closure, n2 = 60) patients had their extraction sockets partially closed. Data collected included maximum inter-incisal distance (MID) and facial width which were recorded both preoperatively and postoperatively. What also recorded were postoperative pain intensity and postoperative complications. Results: There were 50 (41.7%) males and 70 (58.3%) females (male to female ratio of 1:1.4);age range was 18-40 years and the mean was 26 ± 10 years. The mean ages of patients in both groups showed no significant difference (group 1 = 26.5 ± 7.2;group 2 = 27.1 ± 8.1). The pain was maximal at the first postoperative day review and it gradually reduced in intensity towards the preoperative values for both groups. The pain perceptionsin patients in group 2 were however significantly lower than those of group 1 on days 1 and 3 but not statistically different on day 7. The mean difference in the postoperative and preoperative MID was greatest on the 1st postoperative day and gradually became smaller on the subsequent review days. Comparison of this mean difference between the 2 groups however showed a significant difference in the 2 groups only on day 7. Maximal swelling was noted in both groups on the third postoperative day. A comparison of the mean facial width between the two groups showed no statistically significant difference on all the review days. The postoperative complication rate was 5% in both groups. Conclusions: The results of the study indicate that there was a comparative reduction in postoperative sequelae namely pain and trismus after impacted mandibular third molar surgery when a partial wound closure technique was done. However, there was no significant difference in the postoperative complication rate between the two groups.
文摘Double teeth refer to two teeth that are totally or partially joined by dentin and maybe their pulps. These developmental anomalies may be the result of either gemination or fusion. This is a case of a 15-year-old Indo-Trinidadian male who presented with the fusion of a mandibular third molar with a distomolar as an incidental finding. The patient had his general dental care provided by a paediatric dentist and was referred to an oral and maxillofacial radiologist, orthodontist, and oral surgeon for consultation. A Cone-beam CT was taken to supplement the plain film periapical and orthopantomogram radiographs. It showed the three-dimensional orientation of the double molar and the extent of joining. This is the first case of fusion of a mandibular third molar to a distomolar being reported in the Caribbean.
文摘Osteoradionecrosis(ORN),a pathological condition characterized by a nonvital bone occurring in the site of radiation injury,is one of the significant risks following extraction of highly impacted third molar teeth in patients treated with head&neck radiotherapy for oral cancer.Therefore,the surgery’s meticulous planning is essential to avoid such complications.This case report describes a 63-year-old male patient diagnosed with an impacted lower third molar(tooth#38)with concurrent basal cell carcinoma of the right ear and squamous cell carcinoma of the right vocal cord treated with radiotherapy.Taking into account the patient’s health status,a minimally invasive osteotomy and a corono-radicular separation procedure were performed.This procedure allowed us to reduce the risk of mandibular ORN.Three years later,the healing was complete,and the situation was stable.
文摘BACKGROUND Extraction of impacted third molars often leads to severe complications caused by damage to the inferior alveolar nerve(IAN).AIM To proposes a method for the partial grinding of an impacted mandibular third molar(IMM3)near the IAN to prevent IAN injury during IMM3 extraction.METHODS Between January 1996 and March 2022,25 patients with IMM3 roots near the IAN were enrolled.The first stage of the operation consisted of grinding a major part of the IMM3 crown with a high-speed turbine dental drill to achieve sufficient space between the mandibular second molar and IMM3.After 6 months,when the root tips were observed to be away from the IAN on X-ray examination,the remaining part of the IMM3 was completely removed.RESULTS All IMM3s were extracted easily without symptoms of IAN injury after extraction.CONCLUSION Partial IMM3 grinding may be a good alternative treatment option to avoid IAN injury in high-risk cases.
文摘Middle-mesial canals in mandibular molars are present in the population depending on age, sex and ethnicity. However, limited literature alludes to its prevalence. Troughing procedures may enhance identification, cleaning and shaping. This case report expresses the recognition and management of middle-mesial canal in a mandibular second molar of 24 years old Hispanic-Latino male.
文摘BACKGROUND Most physicians consider molars with chronic apical periodontitis(CAP)lesions as contraindications for immediate implant placement.At the patient’s request,we perform immediate implant placement of the mandibular molars with CAP in clinical practice.AIM To retrospectively analyze and compare the 5-year outcomes of immediate implant placement of the mandibular molars with CAP and those without obvious inflammation.METHODS The clinical data of patients with immediate implant placement of the mandibular molars in the Department of Oral and Maxillofacial Surgery,the Affiliated Hospital of Qingdao University,from June 2015 to June 2017 were collected.The patients were divided into CAP(n=52)and no-CAP(n=45)groups.Changes in bone mineral density and bone mass around implants were analyzed 5 years after implant restoration.RESULTS At 5 years after implantation,the peri-implant bone mineral density was 528.2±78.8 Hounsfield unit(HU)in the CAP group and 562.6±82.9 HU in the no-CAP group(P=0.126).Marginal bone resorption around implants did not differ significantly between the two groups,including buccal(P=0.268)or lingual(P=0.526)resorption in the vertical direction or buccal(P=0.428)or lingual(P=0.560)resorption in the horizontal direction.Changes in the peri-implant jump space did not differ significantly between the two groups,including the buccal(P=0.247)or lingual(P=0.604)space in the vertical direction or buccal(P=0.527)or lingual(P=0.707)space in the horizontal direction.The gray value of cone-beam computed tomography measured using Image J software can reflect the bone mineral density.In the CAP area,the gray values of the bone tissue immediately and 5 years after implant placement differed significantly from those of the surrounding bone tissue(P<0.01).CONCLUSION The results of this study suggest that immediate implant placement of the mandibular molars with CAP can achieve satisfactory 5-year clinical results,without significant differences in the complications,survival rate,or bone tissue condition from the no-CAP mandibular molars.
基金Natural Science Foundation of Jiangsu Province, No. SBK2021021787the Major Project of the Health Commission ofJiangsu Province, No. ZD2022025and the Key Project of the Nanjing Health Commission, No. ZKX20048.
文摘BACKGROUND The relation between orthodontic treatment and temporomandibular disorders(TMDs)is under debate;the management of TMD during orthodontic treatment has always been a challenge.If TMD symptoms occur during orthodontic treatment,an immediate pause of orthodontic adjustments is recommended;the treatment can resume when the symptoms are managed and stabilized.CASE SUMMARY This case report presents a patient(26-year-old,female)with angle class I,skeletal class II and TMDs.The treatment was a hybrid of clear aligners,fixed appliances and temporary anchorage devices(TADs).After 3 mo resting and treatment on her TMD,the patient’s TMD symptom alleviated,but her anterior occlusion displayed deep overbite.Therefore,the fixed appliances with TAD were used to correct the anterior deep-bite and level maxillary and mandibular deep curves.After the levelling,the patient showed dual bite with centric relation and maximum intercuspation discrepancy on her occlusion.After careful examination of temporomandibular joints(TMJ)position,the stable bite splint and Invisible Mandibular Advancement appliance were used to reconstruct her occlusion.Eventually,the improved facial appearance and relatively stable occlusion were achieved.The 1-year follow-up records showed there was no obvious change in TMJ morphology,and her occlusion was stable.CONCLUSION TMD screening and monitoring is of great clinical importance in the TMD susceptible patients.Hybrid treatment with clear aligners and fixed appliances and TADs is an effective treatment modality for the complex cases.
文摘The aim of this study was to investigate the physiological foramen diameter, shape and distance between physiological and anatomical apex of maxillary and mandibular first and second molars. Accurate knowledge of the physiological foramina morphology; thus, inherent mechanical shaping technical hindrances, is decisive when taking the corresponding root canal final preparation decision. The morphological dimensions of a total of 1 727 physiological foramina were investigated by means of micro-computed tomography. Mean narrow and wide(to a high number, oval) diameters of the physiological foramen were 0.24,0.22 and 0.33 mm and 0.33, 0.31 and 0.42 mm in mesiobuccal(MB), distobuccal(DB) and palatal(P) roots in maxillary first molars; 0.24, 0.22 and 0.33 mm and 0.41, 0.33 and 0.44 in MB, DB, and P roots in maxillary second molars. Mandibular first molars showed mean narrow and wide diameters of 0.24 and 0.30 mm and of 0.39 and 0.46 mm in mesial(M) and distal(D)roots; second mandibular molars showed 0.25 and 0.31 mm and 0.47 mm in M and D roots. The mean distance between the physiological foramina and anatomical apex was 0.82, 0.81 and 1.02 mm and 0.54, 0.43 and 0.63 mm in MB, DB and P roots of the maxillary first and second molars, respectively. A mean distance of 0.95 mm(M) and 1.05 mm(D) in the first and0.78 mm(M) and 0.81 mm(D) in the second mandibular molars was observed. Based on the results obtained, assumable recommendations for final preparation size of the physiological foramen were calculated. However, when taking into consideration, the resulting standard deviations of marginal errors must be cautiously considered when taking a final decision in clinical endodontic treatment.
基金supported by the grant from the Independent Innovation Foundation of Shandong University of China (No. 2011JC019)the grant of Science and Technique Development Foundation of Shandong province(2010G0020230)
文摘The aims of the study were to investigate the incidence of C-shaped root canal systems in mandibular second molars in a native Chinese population using radiography and clinical examination under microscope and to compare the relative efficacies of these methods.For the recognition of C-shaped root canal system,1 146 mandibular second molars were selected and examined.Teeth with C-shaped canal systems were categorized by using the radiographic classification criteria and the modified Melton's method.C-shaped canals were identified in 397(34.64%) mandibular second molars by radiography(type I,31.23%;type II,38.29%;type III,30.48%).Clinical examination showed that 449(39.18%) cases exhibited C-shaped canal systems(C1,22.94%;C2,48.11%;C3a,15.59%;C3b,13.36%).As for the result of the radiographic and clinical combined examination,C-shaped root canals were found in 473(41.27%) mandibular second molars(C1,21.78%;C2,45.67%;C3a,16.70%;C3b,15.86%).The incidence of C-shaped root canal diagnosed by radiographic method was statistically different from that by clinical examination and the combined examination(P,0.05).The study indicated a high incidence of C-shaped canal system in a Chinese population.The combination of microscopic and radiographic examination is an effective method in identifying the C-shaped root canal system.
文摘The role of third molars in the oral cavity has been extensively studied over the years. Literature includes numerous diagnostic and treatment alternatives regarding the third molars. However, an issue that has not been discussed at the same level is their involvement in orthodontic therapy. The aim of this study is to present a review of the contemporary literature regarding the most broadly discussed aspects of the multifactorial role of third molars in orthodontics and which are of general dental interest too.
基金supported by the Major Research Program of the National Natural Science Foundation of China(Beijing,Subproject No.81991503)the Changjiang Scholars Program of the Ministry of Education of the People’s Republic of China(2016).
文摘Considering the adverse effects of nonimpacted third molars(N-M3s)on the periodontal health of adjacent second molars(M2s),the removal of N-M3s may be beneficial to the periodontal health of their neighbors.This study aimed to investigate the clinical,immunological,and microbiological changes of the periodontal condition around M2s following removal of neighboring N-M3s across a 6-month period.Subjects with at least one quadrant containing an intact first molar(M1),M2,and N-M3 were screened and those who met the inclusion criteria and decided to receive N-M3 extraction were recruited in the following investigation.M2 periodontal condition was interrogated before M3 extraction(baseline)and at 3 and 6 months postoperatively.Improvements in clinical periodontal indexes of M2s in response to their adjacent N-M3 removal,along with changes in inflammatory biomarkers among gingival crevicular fluid(GCF)and the composition of subgingival plaque collected from the distal sites of the M2s of the targeted quadrant were parallelly analyzed.Complete data of 26 tooth extraction patients across the follow-up period were successfully obtained and subsequently applied for statistical analysis.Compared to the baseline,the periodontal condition of M2s was significantly changed 6 months after N-M3 removal;specifically,the probing depth of M2s significantly reduced(P<0.001),the matrix metalloproteinase(MMP)-8 concentration involved in GCF significantly decreased(P=0.025),and the abundance of the pathogenic genera unidentified Prevotellaceae and Streptococcus significantly decreased(P<0.001 and P=0.009,respectively).We concluded that N-M3 removal was associated with superior clinical indexes,decreased GCF inflammatory biomarkers,and reduced pathogenic microbiome distribution within the subgingival plaque.Although the retention or removal of N-M3s continues to be controversial,our findings provide additional evidence that medical decisions should be made as early as possible or at least before the neighboring teeth are irretrievably damaged.
文摘Surgical extraction of the third molar is the most commonly performed surgical procedure in the clinical practice of oral surgery.Third molar surgery is warranted when there is inadequate space for eruption,malpositioning,or risk for cyst or odontogenic tumor formation.Preoperative assessment should include a detailed morphologic analysis of the third molar and its relationship to adjacent structures and surrounding tissues.Due to developments in medical engineering technology,computed tomography(CT)now plays a critical role in providing the clear images required for adequate assessment prior to third molar surgery.Removal of the maxillary third molar is associated with a risk for maxillary sinus perforation,whereas removal of the mandibular third molar can put patients at risk for a neurosensory deficit from damage to the lingual nerve or inferior alveolar nerve.Multiple factors,including demographic,anatomic,and treatment-related factors,influence the incidence of nerve injury during or following removal of the third molar.CT assessment of the third molar prior to surgery can identify some of these risk factors,such as the absence of cortication between themandibular third molar and the inferior alveolar canal,prior to surgery to reduce the risk for nerve damage.This topic highlight presents an overview of the clinical significance of CT assessment in third molar surgery.
文摘Extraction of the lower third molar is one of the most common procedures performed in oral surgery. In general, impacted tooth extraction involves sectioning the tooth’s crown and roots. In order to divide the impacted tooth so that it can be extracted, high-speed air turbine drills are frequently used. However, complications related to air turbine drills may occur. In this report, we propose an alternative tooth sectioning method that obviates the need for air turbine drill use by using a low-speed straight handpiece and carbide bur. A 21-year-old female patient presented to the institute’s dental hospital complaining of symptoms localized to the left lower third molar tooth that were suggestive of impaction. After physical examination, tooth extraction of the impacted left lower third molar was proposed and the patient consented to the procedure. The crown was divided using a conventional straight low-speed handpiece and carbide bur. This carbide bur can easily cut through the enamel of crown. On post-operative day number five, suture was removed and the wound was extremely clear. This technique could minimise intra-operative time and reduce the morbidity associated with air turbine drill assisted lower third molar extraction.
文摘The estimation of chronologic age based on the stages of third-molar development was evaluated by using the eight stages (A–H) method of Demirjian and the third-molar development was compared, in terms of sex and age, with results of previous studies. The samples consisted of 291 orthopantomograms from young Chinese subjects of known chronologic age and sex (including 139 males with a mean age of 14.67±3.62 y and 152 females with a mean age of 14.85±3.70 y). Statistical analysis was performed by employing the Mann-Whitney U-test and the t-test. Regression analysis was conducted to obtain regression formulas for calculating dental age from the chronologic age. Our results showed statistically significant differences (P<0.05) in third-molar development between males and females, at the calcification stages D, E and H. And a strong correlation was found between age and third-molar development in both males (r2=0.65) and females (r2=0.61). New equations (Age=8.76+1.32 Development stage) for estimating chronologic age were derived. It is concluded that third-molar genesis took place earlier in males than in females. The use of third molars as a developmental marker is appropriate in young adults of Central China. The formula obtained in the present study can be used as a guide for estimation of dental maturity and a standard for age estimation for young adults of Central China.
文摘This paper reported a case of fusion between an impacted third molar and a supernumerary tooth, in which a surgical intervention was carried out, with the objective of removing the dental elements. The panoramic radiography was complemented by the Donovan's radiographic technique; but because of the proximity of the dental element to the mandibular ramus, it was not possible to have a final fusion diagnosis. Hence, the Cone-Beam Computed Tomography―which provides precise threedimensional information―was used to determinate the fusion diagnosis and also to help in the surgical planning. In this case report we observed that the periapical, occlusal and panoramic were not able to show details which could only be examined through the cone-beam computed tomography.
