R.B. Donoff

Healing of bony defects in the irradiated and unirradiated rat mandible

A model system of the irradiated rat mandible has been developed and used in conjunction with a non-spontaneously healing mandibular defect. The contribution of the tissue components in the healing of bony defects was studied using demineralized bone powder (DBP) prepared from unirradiated or in vivo irradiated rat long bones. Better bony fill of the defects occurred in the irradiated beds filled with unirradiated DBP than in the unirradiated beds containing irradiated DBP. This suggests that, at least in the early postirradiation period, the bed is not the limiting factor in healing of bony defects and the osteogenic components of bone in the DBP may be most affected by irradiation. In the irradiated bed, the defects grafted 2 weeks after irradiation healed better than those grafted at 4 weeks. Thus, the timing of surgery after irradiation also plays a role in the healing process, with early surgery producing better results.

Free and microvascular bone grafting in the irradiated dog mandible

Microvascular and free rib grafts were placed in 4.5 cm defects in an edentate mandibular body defect 18 to 28 days after completion of 50 Gy of irradiation from a 60Co source. The animals were sacrificed from two to forty weeks postoperatively and evaluated clinically, radiographically, and histologically. There was a marked difference in the alveolar mucosal viability with the two grafts. Mucosal dehiscence was not observed over any of the microvascular grafts, but was present in seven-eighths of the free grafts. Union of the microvascular bone graft to the host bone occurred within six weeks. In contrast, after six weeks the free graft was sequestered in all the animals. An unexpected finding with both types of graft was the marked subperiosteal bone formation. This bone appeared to be derived from the host bed, stabilizing and bridging the defects bilaterally. The results suggest that radiated periosteum may play an important role in osteogenesis.

Bone regeneration after mandibular resection: Report of two cases

Abstract Bone, unlike soft tissue and nerve healing, comes the closest to actual tissue regeneration during repair. Ossesous tissue, through a series of synthetic and resorptive events, in the presence of various external stimuli achieves a remarkable degree of similarity to the native tissue. Two potential sources of new tissue that operate in bone repair are located at endosteal and periosteal sites. This article focuses on the periosteal response by examining the clinical outcome after mandibular resection in two patients.

Healing of cutaneous and mucosal wounds grafted with collagen-glycosaminoglycan/Silastic bilayer membranes: A preliminary report

This report describes the healing of cutaneous wounds in experimental animals grafted with collagen-glycosaminoglycan (GAG) matrix/Silastic (Dow Corning Corp., Midland, MI) bilayers; assesses the feasibility of using collagen-GAG matrix as a vehicle for delivering culture-selected, autogenous fibroblasts to cutaneous wound sites; and evaluates the use of collagen-GAG/Silastic bilayers as mucosal substitutes. Cutaneous and mucosal wounds in New Zealand white rabbits were grafted with either acellular collagen-GAG/Silastic membrane or collagen-GAG/Silastic membrane previously seeded with cultured autogenous fibroblasts. Over 63 days, wound sites were analyzed at intervals based on wound contraction and histology. Cutaneous wound successfully incorporated grafted collagen-GAG matrix and were significantly inhibited in their rate and extent of wound contraction. Seeding membrane matrices with autogenous, cultured fibroblasts before grafting caused a marked increase in cellularity that persisted throughout the postgraft period. In mucosa, matrices were exteriorized rather than incorporated. This work suggests that collagen-GAG/Silastic bilayer may have value as a dermal substitute and, more significantly, may be appropriate as a vehicle for delivering culture-selected fibroblasts to cutaneous wound sites.

What Factors Are Associated With Functional Sensory Recovery Following Lingual Nerve Repair

PURPOSE To identify factors associated with functional sensory recovery (FSR) after lingual nerve repair. MATERIALS AND METHODS This retrospective cohort study was composed of subjects who underwent lingual nerve repair from 2004 through 2010. The predictor variables were demographic, anatomic, and operative measurements. The primary outcome measurement was FSR (ie, FSR achieved, yes or no). The secondary outcome measurements were time to FSR and an improvement of at least 2 levels on the British Medical Research Council scale of neurosensory function. Descriptive, bivariate, and multiple logistic regression statistics were computed to identify associations between the predictor variables and FSR. A Cox proportional hazards model was used to identify associations between the predictors and time to FSR. P ≤ .05 was considered statistically significant. RESULTS The sample was composed of 55 subjects with a mean age of 30.7 ± 11.2 years. The mean duration from injury to repair was 151.6 days (range, 41 to 384 days). Most patients (74.5%) achieved FSR postoperatively, with a mean time to FSR of 262.8 days (median, 208 days). Eighty-six percent of subjects showed an improvement of at least 2 levels on the British Medical Research Council scale. In multiple regression models, younger subjects were more likely to achieve FSR (odds ratio, 1.10; 95% confidence interval, 1.01 to 1.18; P = .02); subjects with better preoperative neurosensory function achieved FSR faster (hazard ratio, 1.9; 95% confidence interval, 1.2 to 3.1; P = .01). CONCLUSION Most patients undergoing lingual nerve repair achieved FSR. Younger subjects were more likely to achieve FSR. Subjects with better preoperative neurosensory function achieved FSR faster.

Problems and Solutions for Interprofessional Education in North American Dental Schools

Interprofessional education (IPE) is a relatively new part of dental education. Its implementation is mandated by accreditation standards, but it is also essential to good patient care. Diverse dental schools from various regions of North America outline problems they have faced in IPE and the solutions that they have found to surmount these problems. Commonalities and unique features of these problems and solutions are discussed.