Adhesion of resin composite to hydrofluoric acid-exposed enamel and dentin in repair protocols.

Intraoral repairs of ceramic fixed-dental-prostheses (FDP) often include cervical recessions that require pretreatment of the exposed tooth surfaces either before or after the ceramic is conditioned with hydrofluoric (HF) acid gel. The sequence of repair protocol may cross-contaminate the exposed etched enamel or dentin surfaces during the application or rinsing process and thereby affect the adhesion. This study evaluated the influence of HF acid gel with two concentrations on bond strengths of composite to enamel and dentin. Human third molars (N=100, n=10 per group) with similar sizes were selected and randomly divided into 10 groups. Flat surfaces of enamel and dentin were created by wet ground finishing. Before or after the enamel (E) or dentin (D) was conditioned with phosphoric acid (P), substrate surfaces were conditioned with either 9.5% HF (HF(9.5)) or 5% HF (HF(5)). Subsequently, a bonding agent (B) was applied. The experimental groups by conditioning sequence were as follows where the first letter of the group abbreviation represents the substrate (E or D) followed by the acid type and concentration: group 1 (EPHF(9.5)), group 2 (EPHF(5)), group 3 (EHF(9.5)P), group 4 (EHF(5)P), group 5 (DPHF(9.5)), group 6 (DPHF(5)), group 7 (DHF(9.5)P), and group 8 (DHF(5)P). Group 9 (EPB) and group 10 (DPB) acted as the control groups. Repair resin was adhered incrementally onto the conditioned enamel and dentin in polyethylene molds. Each layer was photo-polymerized for 40 seconds. All specimens were thermocycled (×1000, 5°-55°C) and subjected to shear test (universal testing machine, 1 mm/min). Specimens that debonded during thermocycling were considered as 0 MPa. The bond strength data were analyzed using Kruskal-Wallis test and failure types using the chi-square test (α=0.05). Overall, the bond results (MPa) were lower on dentin than on enamel (p<0.01). EPB (25.6 ± 6.6) and DPB (20.2 ± 4.9) control groups showed significantly higher results than those of other groups (p<0.05). While higher mean bond strengths were obtained in group 1 (EPHF(9.5)) (11.5 ± 2.1) and group 2 (EPHF(5)) (7.3 ± 0.6), lower results were obtained when HF acid gels were applied prior to phosphoric acid (EHF(9.5)P: 5.0 ± 1.1, EHF(5)P: 3.6 ± 0.1) (p<0.05). On dentin, the results were the lowest in group 8 (DHF(5)P: 1.5 ± 1.6), being significantly lower than those of group 5 (DPHF(9.5)) (p<0.05). Scanning electron microscope (SEM) images revealed predominantly mixed failures with less than half of the composite left on both enamel and dentin surfaces (64 out of 80) (p<0.05), indicating that in general, adhesion was not ideal. Contamination of the enamel or dentin surfaces with HF acid gel impairs the bond strength of composites. Considering both the bond strength results and failure types, when dental tissues are to be repaired next to ceramic, application of phosphoric acid before HF acid gel application can be recommended. HF acid gel concentration did not influence the results except on enamel.

Application of fractal analysis in hyperparathyroidism.

OBJECTIVES: Primary hyperparathyroidism (HPT) is a condition caused by an overproduction of parathormone, in excess of the amount required by the body. Its most common cause is a parathyroid gland adenoma and parathyroidectomy is currently the only curative treatment for primary HPT. We present a case history of a 65-year-old patient who was diagnosed with primary HPT after the recognition of dental problems. METHODS: Dental complaints of the patient alerted the dentists, and the patient was referred for further medical evaluation. In addition to his current medical status, his medical records including the biochemical parameters of bone metabolism recorded between 2001 and 2006 were reviewed. The panoramic films of the patient obtained between 1997 and 2008 were also assessed with the fractal analysis method. RESULTS: After consideration of the radiographical, biochemical and clinical evaluations of the patient, the final diagnosis was made as hyperparathyroid adenoma and surgical removal was scheduled. Soon after surgery, alkaline phosphatase, calcium and intact parathormone levels returned to normal. The fractal analysis value of the mandibular alveolar bone also increased. CONCLUSIONS: Dentoalveolar changes observed in HPT include alveolar bone demineralization. The fractal dimension (FD) analysis of the bone tissue has been introduced as an alternative method to investigate the quality of the alveolar bone. FD values of the patient showed osteoporotic bone characteristics between 1997 and 2006 until the date of parathyroidectomy. Mandibular bone FD analyses revealed a prominent development, which was also observed in dual energy X-ray absorptiometry values.

Effect of various surface treatment methods on the bond strength of the heat-pressed ceramic samples.

This in vitro study was conducted to evaluate the interaction between the shear bond strength and the surface treatment method for a commercial dental ceramic. Ninety bonded ceramic units were manufactured for this study. Each unit was made by luting two cylinder-shaped ceramic samples to each other with a resin-composite luting agent. The units were then divided into nine groups, containing 10 units in each group. Samples from each group were treated with one of the following: etching with 4.9% hydrofluoric acid for 10, 20 and 40 s, 9.5% hydrofluoric acid for 10, 20 and 40 s, 40% orthophosphoric acid for 40 s, air abrasion with alumina in 50-microm particles, and grinding with a high-speed diamond bur. The treated samples were then silanated and luted with a resin-composite luting agent. The luted units were then loaded to failure. Two samples from each group were neither silanated nor luted after the surface treatment procedure, and morphological changes obtained by various surface treatment regimens were investigated by scanning electron microscopy. A statistically significant difference was observed among the mean shear bond strengths of the groups prepared with different surface treatment techniques (P = 0.00). Hydrofluoric acid appeared to be the most suitable chemical medium to produce a reliable ceramic bond. Etching time and concentration of the acidic medium were also observed as important prognostic variates. Orthophosphoric acid treatment was observed to be the least effective surface treatment method on the heat-pressed ceramic samples. Physical applications such as bur grinding and air blasting maintained stronger bonds than the orthophosphoric acid, while producing weaker bonds than surfaces treated with hydrofluoric acid in all concentrations and etching periods. The effect of the silane priming agent was not considered in this study.

The efficacy of intra-articular sodium hyaluronate in patients with reducing displaced disc of the temporomandibular joint.

In this clinical trial, we examined the efficacy of intra-articular hyaluronic acid (HA) treatment in 38 patients with reducing displaced disc of the temporomandibular joint (TMJ). Subjects received two unilateral upper space injections of HA or physiological saline solution with 1 week apart. Efficacy was based on the following measurements: pain and sound intensity of the joint measured by visual analogue scale (VAS), modified Helkimo's clinical dysfunction index and the intensity of joint vibration during opening and closing the mouth measured by accelerometers. These measurements were performed before the first injection and 1 and 6 months after the last injection. In the treatment group (n=19), all measurements improved significantly at month 1 and at month 6 compared with the baseline (P < 0.01). The same measurements, in the placebo group (n=19), did not show any change, except for the pain intensity which improved at month 1 and month 6 (P < 0.05). The change in baseline measurements of all of the efficacy criteria at month 1 and at month 6 in the treatment group was significantly better compared with the change obtained with placebo at the same time intervals. This study demonstrates that intra-articular sodium hyaluronate (Orthovisc) injection into the TMJ is an effective treatment for a reducing displaced disc.