Effect of photofunctionalization on titanium bone-implant integration in ovariectomized rats.

Osteoporosis is considered a risk factor for osseointegration during implant treatment. Photofunctionalization of titanium has been shown to improve bone-based cell adhesion, proliferation, and functional expression, increasing the bone-implant contact rate and bone-implant integration strength. This study aimed to test the hypothesis that photofunctionalization is effective for implant fixation using an osteoporosis rat model. In the biomechanical push-in test, the bone-implant integration strength of the photofunctionalization treatment group was 1.53 times that of the control group (p<0.05). These values implied that photofunctionalization restored the ovariectomy-induced low bone-implant integration strength to normal states. In the micro-CT analysis, the BV/TV of the photofunctionalization treatment group was 1.32 times that of the control group (p<0.05). These values implied that photofunctionalization restored the ovariectomy-induced low peri-implant bone formation to normal states. These results indicate that photofunctionalization treatment increased peri-implant bone formation and bone-implant integration strength in ovariectomized rats.

Stereolithographic Surgical Guide with a Combination of Tooth and Bone Support: Accuracy of Guided Implant Surgery in Distal Extension Situation.

A distal free-end situation could result in insufficient stability of the surgical guide, and could reduce accuracy of the static guided implant surgery (sGIS). The purpose of this study was to investigate the accuracy of sGIS using a combination tooth-and-bone supported stereolithographic (SLA) surgical guide in distal extension situation. Thirty dentists, each placed three implants at the Federal Dentaire Internationale (FDI) teeth positions #46, #47 (a distal extension situation), and #36 (a single tooth gap) via the surgical guide on a model fixed to a manikin. Pre- and post-operative computed tomography (CT) images of the models were superimposed, and the positional and angular deviations of the implants were measured with metrology software. An analysis of variance (ANOVA) test was performed to evaluate the intergroup differences. No significant differences were found for all the positional and angular deviations among the three implant sites, except the bucco-lingual deviation at the implant platform in the #47 position (0.43 ± 0.19 mm) that was significantly larger than the #46 (0.21 ± 0.14 mm) and #36 (0.24 ± 0.25 mm) positions (p < 0.0001). Within the limits of this study, we conclude that, in distal extension situation of missing mandibular molars, adding a bone-supported strut in the distal part of the surgical guide can be beneficial to the accuracy of the sGIS.

Hydroxyapatite film coating by thermally induced liquid-phase deposition method for titanium implants.

Thermally induced liquid-phase deposition method was employed to produce a thin hydroxyapatite (HA) film on a titanium substrate in a metastable calcium phosphate solution. Titanium foil of 100x10x0.02 mm3 was used as a substrate. Prior to HA coating, the substrate was immersed in 5 M NaOH solution at 60 degrees C for 24 hours. Substrate temperature was kept constant at 60 degrees C for 0.5-3 hours by electrical heating with a DC power source in the metastable calcium phosphate solution. An X-ray diffractogram indicated that the film deposited on the titanium substrate was composed of HA. The amount of HA deposited increased with increase in heating time. These results suggested that a uniform HA film can be formed by simple chemical and thermal treatments. Based on the results of this study, this technique seemed to be useful for producing uniform HA coatings on complex-shaped and porous dental implants.

In vitro corrosion of dental Ag-based alloys in polyvinylpyrrolidone iodine solution.

The corrosion and tarnish behaviors of three Ag-based alloys (Ag-Pd-Cu-Au alloy, Ag-In alloy, and Ag-Sn-Zn alloy) in polyvinylpyrrolidone iodine (povidone-iodine) solution were examined. The degree of tarnish was evaluated by visible-ray spectrocolorimetry. Corrosion potential measurements and analyses of corrosion products by X-ray diffractometry were carried out to elucidate the corrosion mechanism. The corrosion rate of the three Ag-based alloys in povidone-iodine solution at its practical concentration used as a gargle solution was so fast that the alloys tarnished within 10 seconds of immersion with the formation of AgI. Thermodynamic consideration and the results of surface analysis by X-ray diffractometry revealed that the main anodic and cathodic reactions were Ag + I(-)-->AgI + e- and I2 + 2e(-)-->2I- respectively.

Abutment forms and restorative materials in adhesive prosthesis: a finite element analysis.

This study evaluated experimental abutment forms utilizing adhesion for clinical treatment by the three-dimensional finite element method. Three experimental abutment forms with no axial wall were evaluated: Form 1 was the occlusal surface reduced by 1.5 mm, Forms 2 and 3 were the crown cut perpendicular to the tooth axis 2 mm or 4 mm from the central groove. The restorations were made of 3 types of materials: composite resin, porcelain, and a gold-based alloy. Restorations were bonded to the abutments with an adhesive resin. A vertical load of 500 N was applied to the center of the inner incline of the buccal cusp. The stresses in the adhesives were largest in Form 1 with composite resin and in Form 3. It was indicated that the stresses were greatly affected by the form of the abutment and the restorative materials.