Long-term results of a randomized clinical trial of 2 types of ceramic crowns in participants with extensive tooth wear.

STATEMENT OF PROBLEM: Evidence is sparse regarding the long-term outcomes of restorative treatment of patients with extensive tooth wear. PURPOSE: The purpose of this long-term prospective randomized clinical trial was to evaluate the performance and success rate of pressed lithium disilicate (LD) and translucent zirconia (TZ) crowns in participants with extensive tooth wear. MATERIAL AND METHODS: A total of 62 participants with extensive tooth wear (17 women, 45 men; mean age 44.8 years; range 25-63 years) received a total of 713 crowns, LD=362 and TZ=351. Both types of crowns had chamfer preparations and were adhesively luted with dual-polymerizing composite resin cement (PANAVIA F 2.0; Kuraray Noritake Dental Inc). The restorations were clinically reevaluated on average 14, 31, 39, 54, and 65 months after insertion of the crowns according to the modified United States Public Health Service (USPHS) criteria. RESULTS: After an observation period of up to 6 years, the survival rate for both types of crowns was 99.7%, with 1 lost LD crown after 1 year as a result of loss of retention and 1 lost TZ crown after 3 years because of tooth fracture at the cemento-enamel junction. The success rates were similar for both types of crowns: 98.6% for LD and 99.1% for TZ. Reasons for failures were that 3 participants in each group developed apical lesions, minimal ceramic fractures, or their crowns were rebonded after loss of adhesion. Assessment of color at baseline was significantly different with a better match for LD (84.8% Alfa, 15.2% Bravo) than for TZ crowns (36.5% Alfa, 63.5% Bravo), including TZ crowns with veneered porcelain (P<.001). Secondary caries and cracks did not occur. A post hoc analysis of clinical performance did not indicate any significant differences between extensive tooth wear with primarily mechanical or chemical factors. CONCLUSIONS: No differences were found between the 2 types of ceramic materials concerning the long-term success and clinical performance, except that TZ crowns were rated by a blinded clinician as less esthetic than LD crowns. The use of high-strength ceramic materials, as well as reliable adhesive bonding, are probably the key factors in the long-term success of ceramic crowns in participants with extensive tooth wear independent of the specific etiology.

Phenotypes of patients with extensive tooth wear-A novel approach using cluster analysis.

OBJECTIVES: Explore a new approach to identify phenotypes of tooth wear (TW) patients using an unsupervised cluster analysis model, based on demographic, self-report, clinical, salivary and electromyographic (EMG) findings. METHODS: Data was collected for 34 variables from 125 patients, aged 17-65 years, with a TW index > grade 2. Demographic information and presumed risk factors for chemical and mechanical TW were collected. A 14-item stress scale was completed and salivary flow rates, pH and buffer capacity were measured. Sleep bruxism was assessed with a portable single channel EMG device. RESULTS: The final cluster model comprised 16 variables and 103 patients and indicated two groups of TW patients; 61 participants in cluster A and 42 in cluster B. Cluster assignment was determined by several presumed mechanical risk factors and diseases affecting saliva. Cluster B had the highest percentage of sleep bruxism self-reports (A 1.6%, B 92.9%, p ≤ 0.001), awake bruxism self-reports (A 45.9%, B 85.7%, p ≤ 0.001), heavy sport exercises (A 1.6%, B 21.4%, p = 0.001); and highest percentage of diseases affecting saliva (A 13.1%, B 47.6%, p ≤ 0.001). A notable finding was the lack of significant differences between clusters in many other presumed risk factors for mechanical and chemical TW. CONCLUSION: TW patients can be clustered in at least two groups with different phenotypic characteristics but also with a large degree of overlap. Based on this type of algorithm, tools for clinical application may be developed and underpin TW classification and treatment planning in the future.

Clinical presentation of two phenotypes of tooth wear patients.

OBJECTIVE: To assess the clinical presentation of wear lesions in two phenotypes of tooth wear (TW) patients based on distribution and morphological features of wear. MATERIALS AND METHODS: 103 patients (mean age = 43.1 years) were divided into two groups based on cluster analysis; cluster A (61 patients) and cluster B (42 patients). The distribution of wear lesions, scores of presence or absence of 10 defined morphological TW criteria and number of teeth fulfilling each criteria were compared between groups. Intra- and inter-examiner reliability of the 10 TW criteria was determined by Cohen's kappa and intraclass correlation coefficient. RESULTS: While cluster A had more wear in maxillary anterior teeth and mandibular molars compared with the same opposing tooth groups (p < 0.001, p < 0.007 respectively), there were no differences for cluster B. Cluster A was characterized by higher prevalence of 4 chemical morphological criteria and the highest number of teeth affected by one chemical criteria, whereas cluster B had a higher prevalence of one mechanical criteria and higher number of teeth affected by an additional mechanical criteria. Both intra- and inter-examiner values for the defined TW criteria were fair to excellent. CONCLUSION: The results may indicate a more chemical background for TW in cluster A and mechanical background in cluster B. Furthermore, clinicians may use certain clinical features of TW to distinguish between individuals who belong to a specific TW cluster with a presumed chemical or mechanical etiology. These preliminary findings need to be confirmed in future studies.