The influence of bone mechanical properties and implant fixation upon bone loading around oral implants.

Finite element models were created to study the stress and strain distribution around a solitary BAnemark implant. The influence of a number of clinically relevant parameters was examined: bone-implant interface (fixed bond versus frictionless free contact), bone elastic properties, unicortical versus bicortical implant fixation and the presence of a lamina dura. Bone loading patterns in the vicinity of the implant seem to be very sensitive to these parameters. Hence they should be integrated correctly in numerical models of in vivo behaviour of oral implants. This necessitates the creation of patient-dependent finite element models.     

Reconstruction of the alveolar cleft: can growth factor-aided tissue engineering replace autologous bone grafting? A literature review and systematic review of results obtained with bone morphogenetic protein-2

The alveolar cleft in patients with clefts of lip, alveolus and palate (CLAP) is usually reconstructed with an autologous bone graft. Harvesting of autologous bone grafts is associated with more or less donor site morbidity. Donor site morbidity could be eliminated if bone is fabricated by growth factor-aided tissue engineering. The objective of this review was to provide an oversight on the current state of the art in growth factor-aided tissue engineering with regard to reconstruction of the alveolar cleft in CLAP. Medline, Embase and Central databases were searched for articles on bone morphogenetic protein 2 (BMP-2), bone morphogenetic protein 7, transforming growth factor beta, platelet-derived growth factor, insulin-like growth factor, fibroblast growth factor, vascular endothelial growth factor and platelet-rich plasma for the reconstruction of the alveolar cleft in CLAP. Two-hundred ninety-one unique search results were found. Three articles met our selection criteria. These three selected articles compared BMP-2-aided bone tissue engineering with iliac crest bone grafting by clinical and radiographic examinations. Bone quantity appeared comparable between the two methods in patients treated during the stage of mixed dentition, whereas bone quantity appeared superior in the BMP-2 group in skeletally mature patients. Favourable results with BMP-2-aided bone tissue engineering have been reported for the reconstruction of the alveolar cleft in CLAP. More studies are necessary to assess the quality of bone. Advantages are shortening of the operation time, absence of donor site morbidity, shorter hospital stay and reduction of overall cost.     

The influence of the veneering porcelain and different surface treatments on the biaxial flexural strength of a heat-pressed ceramic

STATEMENT OF PROBLEM: The strength of all-ceramic restorations can be adversely affected by surface defects, leading to restoration failures. Additionally, when a 2-layer all-ceramic restoration is required for esthetic purposes, part of the stronger ceramic core material is replaced by veneering porcelain. PURPOSE: This study evaluated the effect of different surface treatments on the strength of a ceramic core material and veneering porcelain, as well as the influence of veneering porcelain on the strength of a 2-layer ceramic structure. MATERIAL AND METHODS: Fifty heat-pressed ceramic cores and 30 veneering porcelain discs (17 mm diameter x 2 mm) were made. From the ceramic core group, 20 discs were selected and reduced to a thickness of 1 mm and veneered with 1 mm of porcelain. These specimens were divided into 2 groups of 10 each. The remaining 30 ceramic core and the 30 veneering porcelain discs were divided into 2 sets of 3 equal sized groups (n=10). Ceramic core groups were prepared for testing having the following surfaces: airborne-particle abrasion, ground, and overglazed. Veneering porcelain groups were tested: as fired (no additional treatment), ground, and overglazed. Biaxial flexural strength was measured using the ball-on-ring test method. All specimens were loaded to fracture. One and 2-way analysis of variance were used to analyze the data (alpha=.05). RESULTS: The ceramic core discs were significantly (P=.001) stronger than the veneering porcelain discs for the airborne-particle abrasion, as-fired, and ground surface treatments (82 +/- 11 MPa vs 51 +/- 8 MPa and 93 +/- 14 MPa vs 60 +/- 6 MPa, respectively). For the overglazed treatment, there was not a significant difference between the core (115 +/- 1 4 MPa) and the veneer materials (107 +/- 14 MPa). The ground 1-layer core was significantly (P=.015) stronger (93 +/- 14 MPa) than the 2-layer with the core tested in tension (72 +/- 19 MPa). There was no significant difference between 1-layer veneer overglazed (107 +/- 14 MPa) and 2-layer discs when tested with the veneer in tension (105 +/- 16 MPa). CONCLUSION: The overglazed surface treatment significantly improved the strength of the materials tested, as well as the strength of 2-layer discs with the veneer in tension. The veneering porcelain influenced the strength of 2-layer specimens only when tested with the ground ceramic core surface in tension.     

Behçet's syndrome

A dentist referred a 35-year-old woman to the department of oral and maxillofacial surgery because of recurrent aphtous-like changes of the oral mucosa and persisting pain. She also experienced similar complaints about her eyes and genitals. This combination of symptoms was suspect for Beh?et's disease.     

Effect of four different opalescence tooth-whitening products on enamel microhardness

OBJECTIVES: The purpose was to evaluate the effect of various Opalescence tooth-whitening products on enamel. METHODS AND MATERIALS: Enamel blocks were exposed to Opalescence PF 10% Carbamide Peroxide (n = 10), Opalescence PF 20% Carbamide Peroxide (n = 10), Opalescence Trèswhite Supreme 10% Hydrogen Peroxide (n = 10) and Opalescence Quick PF 45% Carbamide Peroxide (n = 10) according to the manufacturer's instructions. The control group was enamel blocks (n = 10) kept in artificial saliva. The values were obtained before exposure and after the 14-days treatment period. Enamel blocks were kept in saliva between treatments. Indent marks on enamel blocks were examined using the scanning electron microscope for treatment effects. RESULTS: All four different Opalescence products damaged enamel. The most damage was done when treated for a long period (112 hours). SEM images also showed damage to enamel by all 4 products. Opalescence with 10% and with 20% Carbamide Peroxide showed the highest damage, which also differed significantly (p < 0.05) from the saliva control group (p < 0.05; Tukey-Kramer Multiple comparison test). CONCLUSION: All 4 Opalescence products damaged enamel. Higher damage was done by the 10% carbamide peroxide and 20% carbamide peroxide products because of the much longer exposure period (112 hours in comparison to 7 hours).     

Growth of oral and skin fibroblasts from patients with oral submucous fibrosis

The purpose of the investigation was to evaluate and compare the proliferation (growth) of mouth fibroblasts and skin fibroblasts from patients with oral submucous fibrosis (OSF). Material comprised fibroblasts from fibrous bands situated in the buccal mucosa and from the inner aspect of the forearm of 8 patients with classic features of OSF as well as fibroblasts from 6 buccal mucosa and 8 skin biopsy specimens from healthy non-areca nut chewing individuals. Cells were cultured for 8 days according to standard techniques. Their growth was monitored daily, under optimal conditions as well as exposure to concentrations of arecoline. The data were analyzed using regression analysis, analysis of variance and the Kruskal-Wallis test. We found no statistically significant differences between the proliferation patterns of oral and skin fibroblasts from patients or between those from patients and controls. The reaction of the cells exposed to concentrations of arecoline was similar; at low concentrations (0.1–10 μg/ml) normal growth was maintained, while 100 μg/ml inhibited growth. It is concluded that fibroblasts from mouths affected by OSF have proliferation patterns which fall within normal parameters, that the excessive collagen formation in established OSF is not due to increased fibroblast proliferation and that arecoline does not stimulate fibroblast proliferation.     

Syndromes 14. Rendu-Osler-Weber disease

The Rendu-Osler-Weber disease is due to an autosomal dominant disease with multiple telangiectasia in skin and mucosa. Recurrent bleeding of the nose is due to telangiectasia of the nasal mucosa. Haemorrhage of the oral mucosa also occurs. Extensive arteriovenous malformations can be present in lungs, liver and brain. Treatment of bleedings in the oral mucosa is easily possible by means of coagulation. Patients with pulmonary arteriovenous malformations should receive prophylactic antibiotic treatment before extractions, removal of third molars and subgingival curettage.     

Caries in children and quality of life

Caries is the most prevalent oral disease in children. The majority of caries in toddlers remains untreated, with toothaches as a consequence. Although toothache is an important determinant of the quality of life, prevalence data on toothaches hardly exist. Research results indicate that children's quality of life improves after caries treatment. The question remains which type of treatment is preferable. To address this question, evidence from randomized controlled clinical trials on various treatment methods is needed.