The Use of Custom‐Milled Zirconia Teeth to Address Tooth Abrasion in Complete Dentures: A Clinical Report

A patient exhibited severe abrasion of resin posterior denture teeth including perforation of the denture base. New dentures were provided to explore the application of zirconia teeth for complete dentures. [Correction added to online publication 07 November 2012: “Zirconium” corrected to “Zirconia”.] Traditional denture procedures were combined with fixed prosthodontic CAD/CAM procedures to fabricate custom‐designed four‐tooth posterior segments in hollow crown form to reduce weight and with a retentive form for interlocking to the denture base. The new dentures were successful in reducing wear of the denture teeth over the short‐term follow‐up period.     

Effect of Surface Treatment on the Flexural Strength of Denture Base Resin and Tensile Strength of Autopolymerizing Silicone Based Denture Liner Bonded to Denture Base Resin: An In Vitro Study

Silicone based denture liners are superior to acrylic based denture liners but it has a problem of failure of adhesion with the denture base. To evaluate the effect on the tensile bond strength of silicone based liner and flexural strength of denture base resin when the latter is treated with different chemical etchants prior to the application of the resilient liner. Rectangular specimens of heat cured PMMA (65 × 10 × 3.3 mm³) for flexural strength and (10 × 10 × 40 mm³) for tensile strength were fabricated and divided into four subgroups each. One subgroup of each type acted as a control and the rest were subjected to surface treatment with acetone for 30 s, MMA monomer for 180 s, methylene chloride for 15 s, respectively. Silicone based denture liner was processed between 2 PMMA specimens (10 × 10 × 40 mm³) in the space provided by a spacer, thermocycled (5^–55°C) for 500 cycles and then their tensile strength measurements and flexural strength measurements were done. 180 s of MMA monomer treatment was found to be most effective in improving the bonding between the liner and denture base resin as well as producing the lowest decrease in flexural strength of denture base resin. Chemical treatment of denture base resin improves the bond strength of denture liner but it also decreases the flexural strength of denture base. So careful selection of chemical etchant should be done so as to produce minimum decrease in flexural strength of denture base resin.     

Familial gigantiform cementoma with Ehlers - Danlos syndrome: A report of 2 cases

Ehlers-Danlos syndrome is an autosomal dominant hereditary disorder of connective tissue, while familial gigantiform cementoma is a condition that usually manifests as multiple radiopaque cementum-like masses throughout the jaws. This case report discusses the oral management and prosthetic rehabilitation of two patients presenting familial gigantiform cementoma with Ehlers-Danlos Syndrome.     

In Vitro Tensile Bond Strength of Denture Repair Acrylic Resins to Primed Base Metal Alloys Using Two Different Processing Techniques

Purpose: Approximately 38% of removable partial denture (RPD) failures involve fracture at the alloy/acrylic interface. Autopolymerizing resin is commonly used to repair RPDs. Poor chemical bonding of repair acrylic to base metal alloys can lead to microleakage and failure of the bond. Therefore, ideal repair techniques should provide a strong, adhesive bond. This investigation compared the tensile bond strength between cobalt‐chromium (Super Cast, Pentron Laboratory Technologies, Llc., Wallingford, CT) and nickel‐chromium (Rexalloy, Pentron Laboratory Technologies, Llc.) alloys and autopolymerized acrylic resin (Dentsply Repair Material, Dentsply Int, Inc, York, Pa) using three primers containing different functional monomers [UBar (UB), Sun Medical Co., Ltd., Shiga, Japan: Alloy Primer (AP) Kuraray Medical Inc., Okayama, Japan; and MR Bond (MRB) Tokyuyama Dental Corp., Tokyo, Japan] and two processing techniques (bench cure and pressure‐pot cure). Material and Methods: One hundred and twenty eight base metal alloy ingots were polished, air abraded, and ultrasonically cleaned. The control group was not primed. Specimens in the test groups were primed with one of the three metal primers. Autopolymerized acrylic resin material was bonded to the metal surfaces. Half the specimens were bench cured, and the other half were cured in a pressure pot. All specimens were stored in distilled water for 24 hours at 37°C. The specimens were debonded under tension at a crosshead speed of 0.05 cm/min. The forces at which the bond failed were noted. Data were analyzed using ANOVA. Fisher's PLSD post hoc test was used to determine significant differences (p < 0.05). Failure modes of each specimen were evaluated under a dissecting microscope. Results: Significant differences in bond strength were observed between combinations of primers, curing methods, and alloys. Primed sandblasted specimens that were pressure‐pot‐cured had significantly higher bond strengths than primed sandblasted bench‐cured specimens. The pressure‐pot‐curing method had a significant effect on bond strength of all specimens except Co‐Cr alloy primed with UB. The highest bond strength was observed for both Co‐Cr and Ni‐Cr alloys that were sandblasted, primed with MRB, and pressure‐pot cured. Co‐Cr alloys primed with UB had the lowest bond strength whether bench cured or pressure‐pot cured. Primed specimens generally experienced cohesive bond failures within the primer or acrylic resin. Nonprimed specimens generally experienced adhesive bond failures at the resin/metal interface. Conclusions: Within the limitations of this study, MRB provided the highest bond strength to both Ni‐Cr and Co‐Cr alloys. Generally, bond strength improved significantly when specimens were primed. Pressure‐pot curing, in most cases, resulted in higher bond strength than bench curing. The results of this in vitro study suggest that MRB metal primer can be used to increase bond strength of autopolymerized repair acrylic resin to base metal alloys. Curing autopolymerized acrylic under pressure potentially increases bond strength.     

两种游离端半精密附着体可摘局部义齿的应力分析

目的:研究双侧游离缺失活动义齿使用两种不同类型的半精密附着体固位时周围支持骨的表面应力。方法:采用电阻应变测量法在人体下颌骨标本上测量以冠内栓道式及冠外垂直杆式半精密附着体固位的双侧游离缺失活动)固定联合修复体的表面应力值并做统计分析。结果:冠内附着体在基牙周围牙槽骨上产生的总体应力较大,而冠外附着体在缺牙区牙槽嵴和近缺隙侧基牙远中颈部牙槽嵴上产生的应力较大。结论:冠内附着体适用于远中基牙牙周条件良好的情况,而冠外附着体则适用于缺牙区牙槽嵴条件良好、远中基牙条件相对欠佳的情况。     

Comparison of Stress Dissipation Pattern Underneath Complete Denture with Various Posterior Teeth form: An In Vitro Study

To evaluate the pattern of stress dissipation underneath the complete denture with various angled posterior teeth in both maxillary and mandibular arch. A 3D finite element models of residual ridge, mucosa, denture base in the coronal section were created from the dentures obtained from a patient, which were scanned and modeled. The coronal portion of the teeth was altered to stimulate the cuspal inclination of 0°, 20° and 33°, thus making the models. Special area of interest in bone, denture were selected to record the stresses. An vertical static load of 100N was applied through the mandibular model to the maxillary model. von Mises stresses developed in all the models were interpreted. Statistical analysis for comparison of stress values with different variables (0°–20°, 0°–33°, and 20°–33°) in various predefined areas of coronal section model was done using Student’s t test (paired). Stress of greater magnitude were observed with cuspal teeth i.e. 33° and 20°, where as 0° showed slightly less magnitude of stresses.