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
Distraction osteogenesis is an important technique for the treatment of maxillofacial abnormities and defects. However, distraction osteo- genesis may cause the injury of the inferior alveolar nerve. The relationship ...Distraction osteogenesis is an important technique for the treatment of maxillofacial abnormities and defects. However, distraction osteo- genesis may cause the injury of the inferior alveolar nerve. The relationship between distraction rate and nerve degeneration-regeneration shift remains poorly understood. In this study, 24 rabbits were randomly divided into four groups. To establish the rabbit mandibular distraction osteogenesis model, the mandibles of rabbits in distraction osteogenesis groups were subjected to continuous osteogenesis dis- traction at a rate of 1.0, 1.5 and 2.0 mm/d, respectively, by controlling rounds of screwing each day in the distractors. In the sham group, mandible osteotomy was performed without distraction, Pin-prick test with a 10 g blunt pin on the labium, histological and histomorpho- metric analyses with methylene blue staining, Bodian＇s silver staining, transmission electron microscopy and myelinated fiber density of inferior alveolar nerve cross-sections were performed to assess inferior alveolar nerve conditions. At 28 days after model establishment, in the pin-prick test, the inferior alveolar nerve showed no response in the labium to a pin pricks in the 2 mm/d group, indicating a severe dysfunction. Histological and histomorphometric analyses indicated that the inferior alveolar nerve suffered more degeneration and in- juries at a high distraction rate （2 mm/d）. Importantly, the nerve regeneration, indicated by newborn Schwann cells and axons, was more abundant in 1.0 and 1.5 mm/d groups than in 2.0 mm/d group. We concluded that the distraction rate was strongly associated with the inferior alveolar nerve function, and the distraction rates of !.0 and 1.5 mm/d had regenerative effects on the inferior alveolar nerve. This study provides an experimental basis for the relationship between distraction rate and nerve degeneration-regeneration shift during dis- traction osteogenesis, and may facilitate reducing nerve complications during distraction osteogenesis.展开更多
BACKGROUND In atrophic posterior mandibular areas,where the bone height superior to the inferior alveolar nerve(IAN)is less than 6 mm,short implants are not applicable.Conventional alternatives such as IAN transpositi...BACKGROUND In atrophic posterior mandibular areas,where the bone height superior to the inferior alveolar nerve(IAN)is less than 6 mm,short implants are not applicable.Conventional alternatives such as IAN transposition and various alveolar bone augmentation approaches are technically demanding and prone to complications.CASE SUMMARY Computer-guided dynamic navigation implantation improves the accuracy,predictability,and safety of implant placement.This case report presents a dynamic navigation system-guided trans-IAN implant placement technique,which can successfully treat a posterior mandibular dentition defect when the bone height is only 4.5 mm.The implant was inserted into the buccal side of the IAN and was 1.7 mm away from the IAN.The implantation deviations were controlled within a satisfying range,and the long-term restoration outcome was stable.CONCLUSION Dynamic navigation system-guided trans-IAN implant placement might be a recommended technique for patients with extremely insufficient residual bone height and sufficient bone width in the posterior mandibular area.展开更多
Objective:To study the effect of nerve growth f actor (NGF) and Schwann cells on axon regeneration of the inferior alveolar nerv e following mandibular lengthening with distraction osteogenesis. Methods:Unilateral man...Objective:To study the effect of nerve growth f actor (NGF) and Schwann cells on axon regeneration of the inferior alveolar nerv e following mandibular lengthening with distraction osteogenesis. Methods:Unilateral mandibular osteodistraction was performed i n 9 healthy adult male goats with a distraction rate of 1 mm/d. Every 3 goats we re killed on days 7, 14 and 28 after mandibular lengthening, respectively. The i nferior alveolar nerves in the distraction callus were harvested and processed f or ultrastructural and NGF immunohistochemical study. The inferior alveolar nerv es from the contralateral side were used as controls. Results:On day 7 after distraction, axon degeneration and Schw ann cell proliferation were observed, and very strong staining of NGF in the dis tracted nerve was detected. On day 14 after distraction, axon regeneration and r emyelination were easily observed, and NGF expression started to decline. On day 28 after distraction, the gray scale of NGF immunoreactivity recovered to the n ormal value and the Schwann cells almost recovered to their normal state. Conclusions:Gradual mandibular osteodistraction can result in mild or moderate axon degeneration of the inferior alveolar nerve. Nerve trauma may stimulate the proliferation of Schwann cells and promote the synthesis and s ecretion of NGF in the Schwann cells. Schwann cells and NGF might play important roles in axon regeneration of the injured inferior alveolar nerve following man dibular lengthening.展开更多
Pain during extraction of impacted mandibular third molars which can occur despite adequate local anesthesia is termed as“escape pain phenomenon”.Recently,it was described during elevation of a mesioangular impacted...Pain during extraction of impacted mandibular third molars which can occur despite adequate local anesthesia is termed as“escape pain phenomenon”.Recently,it was described during elevation of a mesioangular impacted mandibular third molar and also while curetting an extracted third molar socket.This phenomenon has been overlooked,as it was previously considered secondary to pressure effect on the inferior alveolar neurovascular bundle(IANB).However,it is unlikely that the pain impulses originate from direct pressure on the IANB,as the nerve is blocked more proximally at its entry into the mandible.The authors speculated that the occasional presence of a neurovascular plexus(NVP)independent of the IANB causes the escape of a pain impulse upon stimulation by root pressure or instrumentation.To validate the presence of such a plexus,a meticulous literature search and review were performed.The search revealed evidence of the occasional presence of a NVP consisting of auriculotemporal and/or retromolar neural filaments.The plexus may be present around the inferior alveolar artery or embedded within the IANB,and does not innervate the tooth.This plexus likely propagates pain impulses only upon stimulation by compression or instrumentation in the apical area of the tooth socket.This theory explains the absence of pain during tooth sectioning and bone guttering in the presence of a complete inferior alveolar nerve block.展开更多
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.
基金supported by the National Natural Science Foundation of China,No.81270015 and 81771046
文摘Distraction osteogenesis is an important technique for the treatment of maxillofacial abnormities and defects. However, distraction osteo- genesis may cause the injury of the inferior alveolar nerve. The relationship between distraction rate and nerve degeneration-regeneration shift remains poorly understood. In this study, 24 rabbits were randomly divided into four groups. To establish the rabbit mandibular distraction osteogenesis model, the mandibles of rabbits in distraction osteogenesis groups were subjected to continuous osteogenesis dis- traction at a rate of 1.0, 1.5 and 2.0 mm/d, respectively, by controlling rounds of screwing each day in the distractors. In the sham group, mandible osteotomy was performed without distraction, Pin-prick test with a 10 g blunt pin on the labium, histological and histomorpho- metric analyses with methylene blue staining, Bodian＇s silver staining, transmission electron microscopy and myelinated fiber density of inferior alveolar nerve cross-sections were performed to assess inferior alveolar nerve conditions. At 28 days after model establishment, in the pin-prick test, the inferior alveolar nerve showed no response in the labium to a pin pricks in the 2 mm/d group, indicating a severe dysfunction. Histological and histomorphometric analyses indicated that the inferior alveolar nerve suffered more degeneration and in- juries at a high distraction rate （2 mm/d）. Importantly, the nerve regeneration, indicated by newborn Schwann cells and axons, was more abundant in 1.0 and 1.5 mm/d groups than in 2.0 mm/d group. We concluded that the distraction rate was strongly associated with the inferior alveolar nerve function, and the distraction rates of !.0 and 1.5 mm/d had regenerative effects on the inferior alveolar nerve. This study provides an experimental basis for the relationship between distraction rate and nerve degeneration-regeneration shift during dis- traction osteogenesis, and may facilitate reducing nerve complications during distraction osteogenesis.
基金Supported by Clinical New Technology and New Business Project (2021)School and Hospital of Stomatology of Wuhan University
文摘BACKGROUND In atrophic posterior mandibular areas,where the bone height superior to the inferior alveolar nerve(IAN)is less than 6 mm,short implants are not applicable.Conventional alternatives such as IAN transposition and various alveolar bone augmentation approaches are technically demanding and prone to complications.CASE SUMMARY Computer-guided dynamic navigation implantation improves the accuracy,predictability,and safety of implant placement.This case report presents a dynamic navigation system-guided trans-IAN implant placement technique,which can successfully treat a posterior mandibular dentition defect when the bone height is only 4.5 mm.The implant was inserted into the buccal side of the IAN and was 1.7 mm away from the IAN.The implantation deviations were controlled within a satisfying range,and the long-term restoration outcome was stable.CONCLUSION Dynamic navigation system-guided trans-IAN implant placement might be a recommended technique for patients with extremely insufficient residual bone height and sufficient bone width in the posterior mandibular area.
基金ThisstudywassupportedbytheNationalNaturalScienceFoundationofChina (No .3 9970 797)
文摘Objective:To study the effect of nerve growth f actor (NGF) and Schwann cells on axon regeneration of the inferior alveolar nerv e following mandibular lengthening with distraction osteogenesis. Methods:Unilateral mandibular osteodistraction was performed i n 9 healthy adult male goats with a distraction rate of 1 mm/d. Every 3 goats we re killed on days 7, 14 and 28 after mandibular lengthening, respectively. The i nferior alveolar nerves in the distraction callus were harvested and processed f or ultrastructural and NGF immunohistochemical study. The inferior alveolar nerv es from the contralateral side were used as controls. Results:On day 7 after distraction, axon degeneration and Schw ann cell proliferation were observed, and very strong staining of NGF in the dis tracted nerve was detected. On day 14 after distraction, axon regeneration and r emyelination were easily observed, and NGF expression started to decline. On day 28 after distraction, the gray scale of NGF immunoreactivity recovered to the n ormal value and the Schwann cells almost recovered to their normal state. Conclusions:Gradual mandibular osteodistraction can result in mild or moderate axon degeneration of the inferior alveolar nerve. Nerve trauma may stimulate the proliferation of Schwann cells and promote the synthesis and s ecretion of NGF in the Schwann cells. Schwann cells and NGF might play important roles in axon regeneration of the injured inferior alveolar nerve following man dibular lengthening.
文摘Pain during extraction of impacted mandibular third molars which can occur despite adequate local anesthesia is termed as“escape pain phenomenon”.Recently,it was described during elevation of a mesioangular impacted mandibular third molar and also while curetting an extracted third molar socket.This phenomenon has been overlooked,as it was previously considered secondary to pressure effect on the inferior alveolar neurovascular bundle(IANB).However,it is unlikely that the pain impulses originate from direct pressure on the IANB,as the nerve is blocked more proximally at its entry into the mandible.The authors speculated that the occasional presence of a neurovascular plexus(NVP)independent of the IANB causes the escape of a pain impulse upon stimulation by root pressure or instrumentation.To validate the presence of such a plexus,a meticulous literature search and review were performed.The search revealed evidence of the occasional presence of a NVP consisting of auriculotemporal and/or retromolar neural filaments.The plexus may be present around the inferior alveolar artery or embedded within the IANB,and does not innervate the tooth.This plexus likely propagates pain impulses only upon stimulation by compression or instrumentation in the apical area of the tooth socket.This theory explains the absence of pain during tooth sectioning and bone guttering in the presence of a complete inferior alveolar nerve block.
