Alveolar distraction before insertion of dental implants in the posterior mandible

We investigated the efficacy of alveolar distraction for reducing crown height:implant length ratio in the posterior mandible. Ten alveolar distractions were done in seven patients. The pre-distraction ratio of required crown height to bone height available for implantation was in all cases > or =1. Two implants were placed in each distracted area (total 20 implants). Before distraction, the mean (SD) predicted crown height was 12.8 (2.1) mm; mean bone height available for implantation was 7.8 (1.5) mm. After distraction and insertion of implants, mean crown height was 8.1 (1.9) mm, and mean implant length was 11.3 (1.9) mm. Before distraction, the mean required crown height:available bone height ratio was 1.7 (0.3); after distraction and insertion of implants, the mean crown:implant ratio was 0.7 (0.2) (P<0.0005). Alveolar distraction is effective for increasing the height of the alveolar ridge in the posterior mandibular region, and should be considered when the height of the predicted crown that is required is greater than or equal to the maximum height of bone available for implantation.     

下颌后牙区软组织水平种植体边缘骨吸收相关因素的临床研究

目的研究下颌后牙软组织水平种植体边缘骨吸收的影响因素,为减少种植体边缘骨吸收量,提高种植体存留率提供理论依据。方法 选择76例患者行下颌后牙区软组织水平种植,共植入种植体116枚。记录患者的一般情况、种植体特征、种植体植入部位特征及修复体特征,在术后即刻、种植后3个月、修复后3个月、修复后12个月行锥形束CT检查,利用One Vlume Viewer软件测量并计算边缘骨吸收量,采用SPSS 20.0软件进行统计学分析。结果 吸烟、骨密质厚度、种植体长轴与牙冠长轴夹角、种植体局部卫生情况在各组间的差异有统计学意义（P<0.05）,患者性别、年龄、种植体长度、种植体直径、种植体系统、种植体边缘骨高度和修复体类型在各组间的差异无统计学意义（P>0.05）。结论 吸烟、骨密质较厚、种植体长轴与牙冠长轴夹角较大、种植体局部卫生差是引起种植体边缘骨吸收的危险因素,其中,局部卫生差与种植体边缘骨吸收的相关性较强。     

Mandibular distraction osteogenesis for endosseous dental implants

Patients with complete or partial edentulism who have insufficient bone for endosseous dental implant treatment present a challenge for the dental practitioner. Alveolar distraction osteogenesis is a technique for creating bone and soft tissue, without the need for bone grafting and its potential complications. In this article, alveolar distraction osteogenesis is compared with traditional bone grafting techniques. A case is presented to illustrate successful bilateral mandibular vertical distraction osteogenesis with creation of adequate bone volume for endosseous implant-supported dental restoration.     

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牵张成骨(distraction osteogenesis,DO)技术是指通过牵张装置对切开后的骨组织施加缓慢而稳定的牵张或扩张力,激活有关细胞的增殖与合成功能,促进骨及相关组织的再生,从而达到增加新骨、矫治骨骼发育不足或修复骨缺损的效果[1].     

Alveolar distraction osteogenesis before placement of dental implants

Distraction osteogenesis of the edentulous alveolar ridges may be considered an alternative to many other augmentation oriented surgical techniques. It is now being widely used for treating severe forms of alveolar ridge atrophy, especially before the placement of dental implants. Leibinger Endosseous Alveolar Distraction System (LEAD; Stryker Leibinger, Kalamazoo, MI) is an intraosseous distraction device used for edentulous ridges. In this study, the healing was uneventful in all 5 cases that were treated except 1, in which the vitality of the distraction segment could not be maintained. No complications related to the prosthodontic restoration were observed.     

Alveolar distraction osteogenesis of bone graft reconstructed mandible

This case report describes a patient who had severe mandibular bony deficiency as a result of excision of aggressive central giant cell granuloma. The defect was reconstructed with iliac bone graft. Four years later vertical distraction osteogenesis was performed on the grafted mandible in order to obtain a satisfactory bony height of mandibular ridge. Distraction osteogenesis can be a good alternative for the reconstruction of mandibular deficiencies.     

The effect of smoking on osseointegrated dental implants. Part II: Peri-implant bone loss

PURPOSE: The detrimental effect of cigarette smoking on implant survival has been previously demonstrated. The purpose of this study was to retrospectively investigate the effect of smoking on marginal bone loss around endosseous dental implants. MATERIALS AND METHODS: The sample consisted of 767 Br?nemark implants placed in 235 patients between 1979 and 1999. Bone level changes were determined using periapical radiographs taken at annual recall visits for 1 to 20 years following prosthesis insertion. Nonparametric tests and multiple linear regression were used to determine the influence of various factors on peri-implant bone loss during the first year of clinical loading and for all subsequent years. RESULTS: The mean annual bone loss was 0.178 mm +/- 0.401 during the first year of clinical loading and 0.066 mm +/- 0.227 per year thereafter. A positive smoking history was associated with a higher rate of peri-implant bone loss, and the majority of implant failures were observed in this group of patients. Smoking at the time of stage 1 surgery did not appear to predispose implants to more marginal bone loss. CONCLUSION: Cigarette smoking should not be an absolute contraindication for implant therapy; rather, long-term heavy smokers must be informed that they are at a slightly higher risk of late implant failure and are susceptible to more marginal bone loss over the long-term, irrespective of their smoking status at the time of implant placement.     

Overcorrection in vertical alveolar distraction osteogenesis for dental implants

A decrease in bone height following alveolar distraction osteogenesis (DO) before implant placement is common, and can be severe when alveolar DO is performed soon after surgical intervention. The aim of this study was to investigate the decrease in bone height after vertical alveolar DO and determine the need for overcorrection with implant placement. Thirty-five patients (17 males and 18 females, mean age 43.9 years) underwent 38 procedures with successful placement of 141 dental implants. Alveolar ridge height was evaluated using digital orthopantomographic radiographs taken shortly after the end of distraction, at consolidation and before implant placement. The mean distraction was 9.7 mm. The total vertical alveolar bone decrease was 2.1mm (21%) during the consolidation period and 3.6mm (37%) at implant placement. Although the 20 sites with a healthy alveolus (surgery >6 months) had bone reductions of 1.5 and 2.5mm (15 and 25%) the 18 sites at which alveolar DO was performed within 6 months (mean 3.0) of surgical intervention had much greater bone loss of 2.7 and 4.8mm (28 and 50%), respectively ((**)P<0.01). These results indicate that any alveolar DO protocol should include a waiting period after the surgical intervention, as well as consider an overcorrection of more than 25% within the limits of the applied surgical protocol.     

Dentigerous cyst after distraction osteogenesis of the mandible

Damage to the dentition or tooth follicle is often cited as a potential complication of Distraction Osteogenesis (DO). The authors describe a case of a dentigerous cyst that developed following DO of the mandible. The possible histogenic mechanisms and the management are outlined. Understanding the causes of dentigerous cysts as well as the anatomy of the neonatal mandible may help avoid such a complication in the future.     

Factors associated with radiographic vertical bone loss around implants placed in a clinical study

The loss of vertical bone height over time has been assessed radiographically as part of the Dental Implant Clinical Research Group studies. Radiographs were assessed from implant placement, uncovering surgeries, and recall appointments. Overall, the study implants experienced most peri-implant vertical bone loss in the first year after placement, followed by a dramatic decrease in bone loss rate through the subsequent study intervals. Stratified analysis of data up to 72 months after implant uncovering indicates different bone loss patterns by: 1) arch; 2) jaw region; 3) case type; 4) bone quality; 5) surface type; 6) implant design; 7) smoking status; and 8) postoperative antibiotic treatment. These results will be used to build statistical mixed models to indicate which clinical factors are most predictive of peri-implant vertical bone loss, controlling for confounding and accounting for correlation of data over time and within study patients.     

Factors affecting late fixture loss and marginal bone loss around teeth and dental implants

Background: The predictability and high success rate of implant treatment have averted attention from factors affecting fixture loss and bone loss around implants. Purpose: The goal of this study was to retrospectively evaluate late fixture loss and marginal bone loss around implants that have been in function for 5 years and to relate these findings to bone loss in the natural dentition. Materials and Methods: One hundred and forty‐three consecutively treated patients who had received an implantanchored fixed prosthesis and completed a 5‐year follow‐up were selected. Intraoral and panoramic radiographs were used to assess bone loss. Results: The bone loss was greater around remaining implants in patients who had lost implants after loading. No correlation was found between bone loss around implants and that around teeth. Only 2% of the fixtures were lost during 5 years of functional load. Most fixture losses occurred in the edentulous maxilla. Seven of the nine patients who lost fixtures were smokers. Conclusion: These findings show that patients who lost implants also lost more bone around the remaining implants. There was no correlation between bone loss around implants and that around teeth, indicating that different interacting mechanisms are involved.     

短种植体在后牙区种植修复的临床观察

目的： ITI短种植体在上下颌后牙区的临床观察及效果评价。方法：选择2005年10月至2013年10月间,在我院接受上下颌后牙区短种植体手术治疗的患者26例,共31枚种植体。随访4月-8年,观察指标包括X线片、临床检查,软组织（指标：牙槽骨吸收情况、牙龈指数、探针深度）等。结果：观察期间未发现短种植体出现松动、断裂,种植部位出现疼痛不适等情况,种植体愈合良好。修复后患者咀嚼功能恢复良好,种植体周围软组织健康,患者对短种植体的修复满意。结论：只要严格选择适应症,规范手术操作,短种植体在一定程度上能解决牙槽骨高度不足的问题,避免复杂的外科手术,减少创伤。     

The effect of electrical stimulation on bone formation around hydroxyapatite implants placed on the rabbit mandible.

Nonresorbable, nonporous, particulate hydroxyapatite (HA) was implanted on the mandible in rabbits and stimulated electrically, 4 hours per day, during the first postoperative week. Stimulated and control implant sites were recovered 8 weeks postoperatively and examined histologically. The HA migrated into the mandible in the electrically treated specimens, and was routinely found in intimate association with preexisting mandibular bone. In the controls, the HA remained superior to the mandibular surface. In further studies (without electrical stimulation) in which the implant site was recovered 26 weeks postoperatively, HA was observed in the mandible; some HA particles migrated completely through the mandible and were found in the adjacent soft tissue. It was concluded that, under the conditions studied, electrical stimulation does not promote bone growth into HA, but rather produces the opposite result--it promotes more rapid movement of HA particles into the mandibular bone. The HA particle migration into the mandible observed (longer postoperative times) in the absence of electrical stimulation suggests that migration is a general property of HA particles when placed over bone under muscle.