Syndromes 22. Rieger's syndrome

Rieger syndrome is a rare autosomal-dominant disorder characterized by defects of the anterior chamber of the eye, failure of the periumbilical skin to involute, and developmental malformations of the dentition. Recognition of the dental anomalies may result in the early diagnosis of this syndrome and prevent progressive visual loss.     

The influence of surface free-energy on planimetric plaque growth in man

The purpose of this study was to examine the change in plaque area over nine days in vivo on four materials with different surface free-energies (s.f.e.). Twelve healthy dental students participated in a cross-over, split-mouth, double-blind study. Supragingival plaque formation was recorded over a nine-day period, on four different materials: fluorethylenepropylene (Teflon) (FEP), parafilm (PAR), cellulose acetate (CA), and enamel (E) with s.f.e. of 20, 26, 57, and 88 erg/cm2, respectively. Strips made from the first three materials were stuck to the buccal surface of an upper incisor. The remaining incisor was carefully polished and served as an enamel surface. The increase in plaque was evaluated after three, six, and nine days. A planimetrical analysis was used so that the plaque area could be expressed as a percentage of the total buccal tooth surface. This procedure was repeated on each subject, so that at the end, each pair of central or lateral incisors received the four tested materials. The results indicated that the adherence of micro-organisms on pellicle-coated substrata was influenced by the material's s.f.e.; there was an association between the s.f.e. of the substrata and the supragingival plaque extension in vivo. High surface free-energy substrata in the oral cavity attracted more micro-organisms than did low energetic materials. Additionally, the bacterial adhesion seemed very weak on surfaces with a low s.f.e.     

The combined use of two endosteal implants and iliac crest onlay grafts in the severely atrophic mandible by a modified surgical approach

Seventeen patients, who received an iliac crest onlay bone graft augmentation to their severely atrophic mandible with simultaneous placement of two endosteal implants by a modified surgical approach, were studied retrospectively. Follow-up ranged from 0.5 to 7.9 years after implant loading with an average follow-up of 4.3 years. Frequency of wound dehiscences and other postoperative complications, the extend of resorption of the initial graft, and the implant success rate were assessed. Two patients, who had a previous history of preprosthetic and implantological procedures at the surgical site, developed a serious wound dehiscence with loss of two implants in one patient and need for antibiotic treatment and sequestrectomy in the other patient. One implant was lost in two other patients with a negative surgical history, resulting in an implant success rate of 88.2%. The average resorption at the last follow up visit was 15% of the initial graft. Damage of the mental nerve was seen in 14.7% of nerves. Our preliminary data indicate that the procedure presented provides a reliable and predictable method for the construction of an implant-bearing overdenture in patients with a severely atrophic mandible. This one-step procedure can not be recommended for patients with a history of surgery in the anterior mandible.     

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).