Healing of onlay mandibular bone grafts covered with collagen membrane or bovine bone substitutes: a microscopical and immunohistochemical study in the sheep

The objective of this study was to evaluate the role of collagen membrane and Bio-Oss coverage in healing of an onlay graft to the mandible. Twelve adult sheep each received an onlay bone graft (experiment 1), bone graft+Bio-Gide (experiment 2), and bone graft+Bio-Oss/Bio-Gide (experiment 3) on the lateral surface of the mandible. The animals were euthanized at 4, 8, 12 or 16 weeks after surgery, and findings were analysed by routine microscopy and immunohistochemistry for proliferation (Ki67) and apoptotic (Caspase-3) markers. Grafts were fully incorporated in all specimens. Pronounced resorption was observed in experiment 1. Minimal loss of graft volume was seen in experiment 2 specimens without membrane displacement. A remarkable increase in the augmented region of the mandible was observed in experiment 3. A high number of osteoclasts were expressed within the grafts during the early healing period, and thereafter declined markedly. Osteoblasts within the grafts expressed a moderate level of Ki67 at 8 weeks, which thereafter declined markedly. The strongest expression of Caspase-3 on the bone surface was observed after 16 weeks. In conclusion, the effect of collagen membrane coverage on bone graft volume maintenance was dependent on membrane stability during healing. An autogenous bone graft covered with Bio-Oss particles resulted in a remarkable increase in augmented lateral surface of the mandible. The late stage of bone graft healing was associated with a high apoptotic induction pathway of osteoblasts lining the surfaces of the new bone, demonstrated by strong positive Caspase-3 immunoreactivity.     

A comparison of Shepard's osteotome versus trapdoor flap technique to harvest iliac crest bone for secondary alveolar bone grafting

OBJECTIVE: To compare the postoperative donor site morbidity and alveolar bone graft results following two different techniques for iliac crest bone graft harvest: a closed (Shepard's osteotome) and an open (trapdoor flap) technique. DESIGN: A retrospective review of two cohorts of alveolar bone grafts performed from 1998 to 2004 in Birmingham Children's Hospital by two surgeons using different harvest techniques. Medical and nursing anesthetic notes and medication charts were reviewed. Alveolar bone graft results were assessed using preoperative and postoperative radiographic studies. PATIENTS: A total of 137 patients underwent an operation. Of these, 109 patients were compatible with the inclusion criteria (data available, first operation, no multiple comorbidities). Sixty-four patients had iliac bone harvested using the open trapdoor technique, while 45 had the same procedure using the closed osteotomy technique. RESULTS: Maximum bone graft volumes harvested were similar with both techniques. The mean length of hospital stay was 50.9 hours for the osteotome and 75.5 hours for the open technique group (p < .0001). The postoperative analgesia requirement was higher and the postoperative mobilization was delayed and more difficult for the open technique patients (p < .0005). Kindelan scores performed by two independent orthodontists were similar for both techniques. CONCLUSION: The findings demonstrate that harvesting bone from the iliac crest using an osteotome technique reduces time in hospital, analgesia requirements, and postoperative donor site morbidity with no detrimental outcome.     

Surgical correction of pseudoankylosis and microgenia: report of case.

The coronoid process was fused to the zygomatic buttress and posterior aspect of the maxilla, resulting in a restricted mandibular opening. In addition to the functional limitation, the patient also had a skeletal deformity of microgenia. A coronoidectomy released the extracapsular ankylosis and restored normal mandibular function, and an augmentation genioplasty corrected a contour deficient chin.     

Retention of dowels subjected to tensile and torsional forces.

This investigation measured the maximal tensile and torsional forces sustained by four different designs of dowels. 1. Under tensile force, the threaded screw-in dowels were significantly more retentive than the unthreaded dowels. 2. Under torque, both the threaded screw-in and serrated dowels were significantly more retentive than the smooth-sided dowels.     

The effect of periodontal treatment on glycemic control in patients with type 2 diabetes mellitus

BACKGROUND, AIMS: This study was designed to explore the effect of periodontal therapy on glycemic control in persons with type 2 diabetes mellitus (DM). METHODS: 36 patients with type 2 DM (treatment group) received therapy for adult periodontitis during an 18-month period. A 36-person control group was randomly selected from the same population of persons with type 2 DM who did not receive periodontal treatment. RESULTS: These groups were well matched for most of the parameters investigated. During the nine-month observation period, there was a 6.7% improvement in glycemic control in the control group when compared to a 17.1% improvement in the treatment group, a statistically significant difference. Several parameters that could confound or moderate this glycemic control were explored. These included the treatment of non-dental infections, weight and medication changes. No moderating effect was associated with any of these variables. However, there were too few subjects in the study to have the statistical power necessary to assess these possible moderators of glycemic control. CONCLUSIONS: We interpret the data in the study to suggest that periodontal therapy was associated with improved glycemic control in persons with type 2 DM.     

The role of dentist, practice and patient factors in the provision of dental services

OBJECTIVES: Service provision varies by dentist, practice and patient factors. However, limited subsets of these potential influences on service rates have been explored. More comprehensive models could improve our understanding of the factors influencing the pattern of care delivered. The aim of this study was to examine variation in dental services by dentist (treatment choice, practice beliefs, preferences for patients, demographics), practice (type, location, size and volume of practice) and patient (visit, demographic, oral health and socio-economic) characteristics. METHODS: A random sample of Australian dentists was surveyed in 1997-98 (response rate=60.3%). Private general practitioners (n=345) provided dentist and practice data, and service provision and patient variables were collected from a log of a typical clinical day (n=4,115 patients). Multivariate negative binomial regression models were fitted for diagnostic, preventive, restorative, extraction and prosthodontic services. RESULTS: Significant dentist factors included (P<0.05; RR=rate ratio): lower diagnostic rates (RR=0.78) for dentists with stronger practice beliefs for giving information about cost and treatment options; preventive rates were lower (RR=0.74) for male dentists and higher (RR=1.48) for younger dentists aged 20-29 years; restorative rates were higher (RR=1.27) for dentists that rated patient preferences more highly in treatment choice and in the dentist age group 30-39 years (RR=1.25); extraction rates were lower (RR=0.61) for dentists with stronger preferences for patients that would adhere with treatment but higher (RR=1.57) for dentists with stronger preferences for sociable patients; and prosthodontic rates were lower (RR=0.38) for dentists with stronger preferences for adaptable patients who were willing to cooperate when expected to do so. Practice factors included: higher preventive (RR=1.28) and prosthodontic rates (RR=2.07) in solo practice; higher preventive (RR=1.34) but lower prosthodontic rates (RR=0.42) in capital cities; lower diagnostic (RR=0.82) and extraction rates (RR=0.55) in practices with fewer other dentists; higher diagnostic (RR=1.33) and extraction (RR=1.62) rates but lower restorative rates (RR=0.84) in practices with lower patient visits per year. Patient factors included: lower preventive (RR=0.76) but higher extraction rates (RR=1.45) for emergency visits; lower extraction rates (RR=0.60) for the insured; higher diagnostic rates (RR=1.17) for new patients; higher restorative (RR=1.31) but lower prosthodontic rates (RR=0.46) for patients with decayed teeth; higher prosthodontic rates (RR=2.14) for those with dentures; and lower preventive (RR=0.66), but higher extraction (RR=2.22) and prosthodontic rates (RR=1.82) for patients from lower socio-economic status areas. CONCLUSIONS: Dental service rates were influenced by large number of small effects from a wide range of dentist, practice and patient factors. Socio-economic and geographic barriers may need broad policy innovations to be addressed, but factors such as insurance and visit type have the potential to be altered to achieve better service outcomes and there is scope for research into clinical outcomes to improve the knowledge upon which treatment decisions are based.     

Effects on smear layer and debris removal with varying volumes of 17% REDTA after rotary instrumentation

The purpose of this study was to quantify the volume of 17% ethylene diamine tetra-acetic acid (EDTA) needed to efficiently remove the smear layer after rotary instrumentation, and to determine if additional irrigation has any effect on debris removal. Forty single canal teeth were instrumented with ProFile GT rotary instruments. Experimental groups were irrigated with 1, 3, or 10 ml of 17% EDTA for 1 min, followed by a final rinse with 3 ml of 5.25% sodium hypochlorite (NaOCl). Samples were scored for debris remaining and examined under SEM to determine quality of smear layer removal. There were no significant differences among groups when comparing either debris remaining or quality of smear layer removal. EDTA irrigation volume greater than 1 ml did not improve debris removal. Efficient removal of the smear layer was accomplished with a final rinse of 1 ml of 17% EDTA for 1 min, followed by 3 ml of 5.25% NaOCl.