Maurizio D'Amario

Fracture Resistance and Deflection of Pulpless Anterior Teeth Restored with Composite or Porcelain Veneers

INTRODUCTION The aim of this in vitro study was to evaluate the influence that resin composite and porcelain veneer restorations, associated or not to fiber post placement, have on fracture resistance and deflection of pulpless anterior teeth. METHODS One hundred twenty freshly extracted human maxillary central incisors were selected. Teeth were randomly divided into 7 experimental groups (veneer preparation/resin composite veneer placement/endodontic therapy and resin composite veneer placement/endodontic therapy, fiber post and resin composite veneer placement/porcelain veneer placement/endodontic therapy and porcelain veneer placement/endodontic therapy, fiber post and porcelain veneer placement) and a control group (n = 15). Specimens were loaded to fracture recording crown deflection, and data were statistically analyzed. RESULTS Veneer preparations did not significantly influence fracture resistance of incisors. On the contrary, veneer preparation significantly increased specimen deflection values. Fiber posts seemed to significantly increase mean maximum load values for endodontically treated teeth restored with either composite or porcelain veneers. CONCLUSIONS A fiber post restoration can be suggested when endodontic treatment is associated with veneer restoration. Veneer restorations seem to be an optimal choice also for endodontically treated teeth.

In Vitro Fracture Resistance and Deflection of Pulpless Teeth Restored with Fiber Posts and Prepared for Veneers

The aim of this in vitro study was to evaluate the influence of endodontic therapy, veneer preparation, and their association on fracture resistance and deflection of pulpless anterior teeth and assess whether restoration with quartz fiber-reinforced post can influence these properties. Seventy-five freshly extracted human maxillary central incisors were selected. Teeth were randomly divided into 4 experimental groups (veneer preparation/endodontic therapy/endodontic therapy and veneer preparation/endodontic therapy, veneer preparation, and fiber post placement) and a control group (n = 15). Specimens were loaded to fracture recording crown deflection under load, and data were statistically analyzed. Veneer preparations and endodontic treatment did not significantly influence fracture resistance of maxillary incisors. On the contrary, preparation for veneer significantly increased the deflection values of the specimens. Fiber post restorations seemed to significantly increase mean maximum load values for specimens prepared for veneers. A fiber-reinforced post restoration can be suggested when endodontic treatment is associated with veneer preparation.

Effect of Repeated Preheating Cycles on Flexural Strength of Resin Composites

The aim of this study was to assess the flexural strengths of three resin composites prepared at room temperature or cured after 20 or 40 cycles of preheating to a temperature of 45°C. Three resin composites were evaluated: Enamel Plus HFO (Micerium) (HFO), Enamel Plus HRi (Micerium) (HRi), Opallis + (FGM) (OPA). One group of specimens for each composite was fabricated under ambient laboratory conditions, whereas in the other groups, the composites were cured after 20 or 40 preheating cycles to a temperature of 45°C in a preheating device. Ten specimens were prepared for each group. A three-point bending test was performed using a universal testing machine at a crosshead speed of 0.5 mm/min. Data were analyzed with a two-way analysis of variance (ANOVA) test and a Games-Howell test (α = 0.05). The two-way ANOVA showed that both the material and the number of heating cycles were significant factors, able to influence the flexural strength values (p<0.05). However, there was not a statistically significant interaction (p>0.05). For all three composites flexural strengths were not affected after 20 preheating cycles in comparison with the control groups (0 preheating cycles) but were, however, significantly decreased when 40 prewarming cycles were conducted. The HRi and OPA groups had the highest flexural strengths, with no statistically significant differences among them. HFO presented significantly lower flexural strengths in comparison with HRi.

Influence of a repeated preheating procedure on mechanical properties of three resin composites.

The aim of this study was to assess the flexural strength, flexural elastic modulus and Vickers microhardness of three resin composites prepared at room temperature or cured after one or repeated preheating cycles to a temperature of 39°C. Three resin composites were evaluated: Enamel Plus HFO (Micerium), Opallis (FGM), and Ceram X Duo (Dentsply DeTrey). For each trial, one group of specimens of each material was fabricated under ambient laboratory conditions, whereas in the other groups, the composites were cured after 1, 10, 20, 30, or 40 preheating cycles to a temperature of 39°C in a preheating device. Ten rectangular prismatic specimens (25 × 2 × 2 mm) were prepared for each group (N=180; n=10) and subjected to a three-point bending test for flexural strength and flexural modulus evaluation. Vickers microhardness was assessed on 10 cylindrical specimens from each group (N=180; n=10). Statistical analysis showed that, regardless of the material, the number of heating cycles was not a significant factor and was unable to influence the three mechanical properties tested. However, a significant main effect of the employed material on the marginal means of the three dependent variables was detected.

Digital Implant Planning for a Minimally Invasive Surgery Approach: A Case Letter of a Full-Arch Rehabilitation

P rosthetically directed implant placement using computer software ensures precise fixture placement and predictable prosthetic outcomes. Computer-guided implant dentistry allows the clinician to position specific implants into presurgically determined sites, taking into account both the jawbone anatomy and the planned prosthesis within the computerized tomography (CT) images. In addition, to obtain the optimal final tooth position, the appliance should be scanned. The use of an appliance scan is essential to digitally plan the treatment and to design and then fabricate a surgical template. The planned prosthesis is integrated with anatomical data using singleor dual-scan protocols. In the single-scan appliance, a radiopaque template allows the teeth to be identified as well as the soft tissue in the CT study. However, scatter from neighboring restorations can obscure the view of teeth in the scan appliance. Also, the use of radiopaque templates reduces the image quality of the jaw bone. In the dual-scan protocol, the patient is scanned with the scan appliance and then the scan appliance is scanned alone with different exposure parameters. The planning software converts the CT scan files and merges the 2 scans by matching radiopaque markers, so that the prosthesis will be visible over the available osseous anatomy, avoiding the image’s noise. In totally edentulous patients, it is possible to use the existing denture as a scan appliance. If the prosthesis is not well fitting and the teeth are not in the correct positions, a new appliance should be fabricated. The potential for patient satisfaction is increased if the patient’s acceptance of the prosthesis is obtained before CT scans are done. The transfer of the virtual planning by means of a surgical drilling guide provides significant benefits in the simultaneous placement of multiple implants, especially in large edentulous areas. Computer-aided design/computer-aided manufacturing (CAD/CAM) technology allows safe flapless surgery to be performed via mucosa-supported guides. The opportunity for an immediately loaded prosthesis can be facilitated by such protocols. In this case letter, a detailed clinical treatment protocol using CAD/CAM computer-guided technology for a maxillary full-arch rehabilitation is presented.

Canal shaping of different single-file systems in curved root canals

Background/Purpose This study compared maintenance of canal anatomy, occurrence of apical transportation, and working time observed after instrumentation with One Shape New Generation rotary system (Micro-Mega), with those observed after instrumentation with Reciproc (VDW) and WaveOne (Dentsply-Maillefer) reciprocating systems. Materials and methods The mesial canals of 45 mandibular molars (curvature angles between 35° and 45°) were selected. Specimens were randomly divided into three groups, and canal preparations were performed using One Shape, Reciproc, or WaveOne systems (size #25). A digital double radiographic technique was used to determine apical transportation and change in angle of curvature. Also, working time and instrument failures were recorded. Data were statistically analyzed. Results During preparation, no file fractured. No statistically significant differences were found among groups. No system showed a significantly faster preparation time than others (P > 0.05). All instruments maintained the original canal curvature well and were safe to use. Conclusion Both continuous rotary instrument and reciprocating systems did not have any influence on the presence of apical transportation or caused an alteration in angle of canal curvature.