Surface characteristics of zirconia-based posterior restorations: clinical and scanning electron microscopic analysis.

AIM: The aim of this prospective clinical trial was to evaluate the performance of zirconia-based all-ceramic posterior fixed partial dentures (FPDs) after 4 years of clinical use. MATERIALS AND METHODS: Fifteen patients who needed 3- or 4-unit posterior FPDs were enrolled in the study. One manufacturer fabricated all restorations, following established clinical protocols and using computer-aided design/computer-aided manufacturing technology and one veneering material. Survival and success were evaluated clinically. Impressions were taken immediately after definitive cementation and after 48 months. Gold-coated epoxy replicas of the restorations were analyzed with scanning electron microscopy (SEM). Surface alterations were also evaluated clinically. RESULTS: After 48 months, the survival rate for the FPDs was 100%. Three restorations exhibited minor chipping, for a fracture rate of 20% after 4 years. Thirty (59%) of the 51 individual restoration units revealed clinically rough occlusal surfaces, a finding that was confirmed by SEM. CONCLUSION: The placement of 3- and 4-unit zirconia-based posterior FPDs can be considered a reliable treatment modality for medium-term clinical use. However, surface alterations of the veneering ceramics were observed after 4 years and are of notable clinical concern.

Noncontact intraoral measurement of force-related tooth mobility.

The aim of this pilot study was to measure force-related tooth mobility. Vertical and horizontal anterior tooth mobility in 31 healthy periodontal subjects was measured by a noncontact optical measurement technique. The subjects continuously increased the force on each tooth by biting on a load cell. An automated software program recorded tooth displacement at 9-N intervals. Vertical and horizontal displacements were subsequently measured. The vector of tooth mobility in the buccal direction was calculated using the Pythagorean theorem. The average displacements over all subjects for each tooth were determined. Global differences were assessed with the Wilcoxon test. There were no significant differences between contralateral teeth overall load stages. There were no significant differences in tooth mobility between the central and lateral incisors except for in the horizontal direction. However, there were significant differences between central incisor and canine and lateral incisor and canine teeth.

Prosthodontic treatment of a patient with bisphosphonate-induced osteonecrosis of the jaw using a removable dental prosthesis with a heat-polymerized resilient liner: a clinical report.

Bisphosphonate-induced osteonecrosis of the jaws (BONJ) is reported frequently in patients receiving oral or intravenous bisphosphonates. To minimize potential complications, dental treatment must be performed with care. There are invasive and noninvasive treatment options for patients with active BONJ or a history of this complication. This clinical report describes the prosthodontic treatment of a patient who developed BONJ after receiving intravenous bisphosphonates (pamidronate). Because of the recurrent incidence of BONJ, noninvasive prosthetic therapy with telescopic overdentures and a heat-polymerized resilient liner was provided. After 2 years, there were no biological or technical complications.

Testing a multistage rating scale for clinical evaluation of all-ceramic surfaces.

PURPOSE: This study tested the applicability of a multistage rating scale based on modified California Dental Association (CDA) criteria and the original criteria of the CDA for surface evaluation of all-ceramic restorations with the use of dental stone replicas, photographs, and scanning electron microscopy (SEM). MATERIALS AND METHODS: Two examiners clinically evaluated 105 all-ceramic restoration units in the posterior region after a mean observation period of 42.2 months; the examiners employed the CDA criteria and a detailed six-stage rating scale. In addition, standardized photographs and gypsum stone and epoxy replicas based on impressions were analyzed blindly using the same rating scales and examiners. SEM images of gold-coated epoxy replicas enabled indirect ceramic surface evaluation, serving as the gold standard to control indirect evaluation and clinical findings. The Cohen kappa was applied to test for concordance; intraclass correlations and Spearman rank correlations were calculated. RESULTS: Statistically significant rating correlations of the clinical situation, photographs, and stone replicas with the SEM photographs were generated from both evaluation systems. With the use of the multistage rating scale, the highest rating correlation was found for stone replica-SEM (r = 0.61, P < .001), and the lowest for clinical photography-SEM (r = 0.5, P < .001). CONCLUSIONS: A multistage rating scale based on modified CDA criteria is reliable for precise assessment of in vivo ceramic surface alterations. Stone replicas were found to be better-suited than photographs for the assessment of all-ceramic surface alterations and confirmation of clinical ratings.

Zirconia posterior fixed partial dentures: a prospective clinical 3-year follow-up.

PURPOSE: The aim of this prospective clinical trial was to evaluate the reliability of three- and four-unit posterior fixed partial dentures (FPDs) with zirconia frameworks after 3 years of clinical function. MATERIALS AND METHODS: Thirty patients, each needing a posterior FPD to restore one or two missing teeth, were included in the study. Preparation guidelines were: occlusal reduction of 1.5 to 2 mm, axial reduction of 1.5 mm, and circumferential chamfer preparation placed 0.5 mm subgingivally. Frameworks were fabricated using a computer-aided design/computer-assisted manufacture technique. All FPDs were cemented with glass-ionomer cement. At baseline and 12, 24, and 36 months after cementation, survival and success of the zirconia framework and the ceramic veneer were evaluated. To analyze the effect of placement of an all-ceramic restoration on the gingival tissue, Gingival Index, Plaque Index, sulcus bleeding index, and pocket depth at abutment (test) and contralateral analogous teeth (control) were assessed. Data were analyzed by descriptive statistics, the Wilcoxon test, and the McNemar test. RESULTS: Of the 30 initial subjects, 27 patients with 27 zirconia FPDs were examined after a mean testing period of 34.2 months. All FPDs were still in use and unfractured, resulting in a 100% survival rate for the frameworks. One FPD exhibited a major chip after 36 months. The cumulative success rate was 96.3%. No significant differences between the periodontal parameters of the test and control teeth were observed. The Plaque Index revealed significantly higher scores for mesial and distal control teeth at baseline and after 12 and 24 months for distal control teeth. CONCLUSION: Posterior zirconia-based three- and four-unit FPDs present a reliable treatment modality after medium-term clinical use.