Effect of restorative, endodontic, and fatigue treatments on the cuspal deflection of maxillary premolars subjected to different cyclic occlusal forces: an in vitro study.

This study aimed to determine the effect of adhesive direct composite restorations, endodontic treatments, and fatigue treatments on the cuspal deflection of maxillary premolars subjected to different cyclic occlusal forces. Thirty intact maxillary second premolars were selected. Ten teeth were left untreated (group IN), 10 teeth were subjected to endodontic and restorative treatment (group FL), and the remaining 10 teeth were subjected to endodontic, restorative, and fatigue treatments (group FT). All teeth were subjected to 5 occlusal compressive loading forces (98, 147, 196, 245, and 294 N) with a universal testing device. A total of 15 experimental groups were obtained with 3 tooth conditions (IN, FL, FT) and 5 different occlusal loading values. Deflection amounts (µm) were measured with laser sensors and recorded, and obtained data were statistically analyzed with one-way analysis of variance at a significance level of .05. Mean cuspal deflection values (µm) and SDs of experimental groups ranged as follows: IN-98 (24.4 ± 19.8), IN-147 (34.8 ± 28.9), IN-196 (43.8 ± 34.7), IN-245 (54.5 ± 46.4), IN-294 (60.3 ± 50.6), FL-98 (56 ± 49.1), FL-147 (62.6 ± 49.6), FL-196 (72.4 ± 52.1), FL-245 (81.3 ± 56), FL-294 (92.2 ± 60.9), FT-98 (77.2 ± 80.9), FT-147 (83.4 ± 81.3), FT-196 (92.6 ± 83.7), FT-245 (102.7 ± 85.4), and FT-294 (124.2 ± 89.5). Mean values of three main experimental groups were as follows: IN (43.5 µm), FL (72.9 µm) and FT (96.0 µm). Significant differences were found between the three main groups and relevant subgroups (P < .001). Highest cuspal deflection values (CDV) were obtained in FT groups. Lowest CDV were obtained in IN groups. FL groups showed higher deflection values than IN groups. CDV increased progressively as the teeth were restored and subjected to fatigue treatment.

Adhesive restoration of endodontically treated premolars: influence of posts on cuspal deflection.

PURPOSE: To determine, by means of a non-destructive experimental procedure, the effectiveness of adhesive restorations in reducing the cuspal deflection of endodontically treated premolars, with or without root canal fiber posts. MATERIALS AND METHODS: The cuspal deflection of ten sound, intact maxillary premolars was evaluated. A loading device induced deformation by axial force (ranging from 98 to 294 N) applied on the occlusal surface of teeth while laser sensors registered the amount of deflection. Once tested, teeth were endodontically treated and the marginal ridges were removed. The teeth were randomly divided into two groups and restored with: group 1) dual curing adhesive, flowable composite, and microhybrid composite; group 2) the same materials associated with root canal glass fiber post and composite cement. The cuspal deflection test was repeated with the same protocol after restorative procedures, allowing a direct comparison of the same samples. Statistical analysis was performed using ANOVA at a significance level of 0.05. RESULTS: Different average cuspal deflection was detected in the two groups: composite resin with post insertion resulted in lower deformation compared with composite alone. Mean deflection ranged from 3.43 to 12.17 µm in intact teeth, from 14.42 to 26.93 µm in group 1, and from 15.35 to 20.39 µm in group 2. ANOVA found significant differences (p = 0.02). CONCLUSION: Bonded composite restorations with fiber posts may be more effective than composite alone in reducing the cuspal deflection in endodontically treated premolars in which the marginal ridges have been lost.

Clinical approach to anterior adhesive restorations using resin composite veneers.

Scientific progress in adhesive dentistry has led to more conservative techniques, both direct and indirect, to solve esthetic problems in anterior teeth. This article will discuss only indirect techniques, which are clearly superior in complex cases in which it will be difficult to recreate harmonious tooth shape and color. After reviewing the literature and highlighting the properties of this technique, the indications and benefits compared to the direct technique will be assessed. This is followed by a step-by-step description of operative procedures, from treatment planning to relining and polishing of the cemented adhesive restoration. The long-term success of veneers depends mainly on the tooth preparation, which should be confined to enamel, involve proximal contact areas, maintain the cervical enamel margin, and incorporate the incisal edge to increase veneer resistance and enable correct placement. Although no clinical follow-up similar to that of ceramic materials is available, the latest-generation resin composites offer interesting features. They can withstand mechanical stress, have excellent esthetic properties, and, most importantly, can be repaired intraorally without impairing their physicochemical and mechanical properties.

Effects of bonded composites vs. amalgam on resistance to cuspal deflection for endodontically-treated premolar teeth.

PURPOSE: To determine, by means of a non-destructive experimental procedure, the extent to which tooth cusps are weakened by endodontic procedures and the effectiveness of adhesive bonding restoration in reducing cuspal deflection as a function of different restorative procedures. METHODS: A mechanically controlled loading device induced cuspal deflection by axial force (range 98-294 N) on an occlusal surface while LTS laser twin sensors registered the amount of deflection. Cusp deflection values, in microns, were recorded for each tooth. Thirty sound maxillary premolars teeth were sequentially evaluated in the following conditions: A) intact tooth; B) completion of endodontic and restorative procedures. Teeth were randomly divided into five groups and restored respectively with: A) amalgam (Dispersalloy); B) Spectrum TPH; C) Surefil; D) Esthet-X; E) Esthet-X + Dyract Flow. RESULTS: The average loading force needed to induce 1 microm cusp deflection was evaluated, for all groups, in intact teeth (range 49.52-58.76 N/microm) and in restored teeth (range 8.56 - 47.05 N/microm). Statistical analysis (ANOVA for repeated measures) has been performed. Mean structural recovery values after restorative treatment were 17% with amalgam, 60% with Spectrum TPH, 59% with SureFil, 54% with Esthet-X, and 99% with Esthet-X/Dyract.