Acellular dermal matrix allograft used alone and in combination with enamel matrix protein in gingival recession: Histologic study in dogs

Gingival recession was created in six mongrel dogs. The dogs were divided into two groups based on treatment: group 1-AlloDerm only, group 2-AlloDerm + Emdogain. The histologic results were compared. At the end of the study, the mean values were, for groups I and 2, respectively: 0.06 and 0.32 mm for cementum regeneration; -0.75 and -0.86 mm for bone regeneration; -2.15 and -3.11 mm for attachment level; and 4.90 and 5.51 mm for defect extent. The epithelial formation parameter was 2.88 mm in group 1 and 2.15 mm in group 2, which was a statistically significant difference. It could be concluded that Emdogain did not result in beneficial effects when associated with AlloDerm.

Early Bone Healing and Biomechanical Fixation of Dual Acid-Etched and As-Machined Implants with Healing Chambers: An Experimental Study in Dogs

Purpose: To evaluate the biomechanical fixation, bone-to-implant contact (BIC), and bone morphology of screw-type root-form implants with healing chambers with as-machined or dual acid-etched (DAE) surfaces in a canine model. Materials and Methods: The animal model included the placement of machined (n = 24) and DAE (n = 24) implants along the proximal tibiae of six mongrel dogs, which remained in place for 2 or 4 weeks. Following euthanasia, half of the specimens were subjected to biomechanical testing (torque to interface failure) and the other half were processed for histomorphologic and histomorphometric (%BIC) assessments. Statistical analyses were performed by one-way analysis of variance at the 95% confidence level and the Tukey post hoc test for multiple comparisons. Results: At 4 weeks, the DAE surface presented significantly higher mean values for torque to interface failure overall. A significant increase in %BIC values occurred for both groups over time. For both groups, bone formation through the classic appositional healing pathway was observed in regions where intimate contact between the implant and the osteotomy walls occurred immediately after implantation. Where contact-free spaces existed after implantation (healing chambers), an intramembranous-like healing mode with newly formed woven bone prevailed. Conclusions: In the present short-term evaluation, no differences were observed in BIC between groups; however, an increase in biomechanical fixation was seen from 2 to 4 weeks with the DAE surface. INT J ORAL MAXILLOFAC IMPLANTS 2011;26:75-82

Bioglass Associated With Leukocyte-Poor Platelet-Rich Plasma in the Rabbit Maxillary Sinus: Histomorphometric, Densitometric, and Fractal Analysis

The objective of the present study was to evaluate the outcomes of autogenous bone graft (AB) and bioglass (BG) associated or not with leukocyte-poor platelet-rich plasma (LP-PRP) in the rabbit maxillary sinus (MS) by histomorphometric and radiographic analysis. Twenty rabbits divided into 2 groups (G1, G2) were submitted to sinus lift surgery. In G1, 10 MS were grafted with AB and 10 MS were grafted with BG. In G2, 10 MS were grafted with AB + LP-PRP and 10 MS were grafted with BG + LP-PRP. After 90 days, the animals were killed and specimens were obtained, x-rayed, and submitted to histomorphometric, radiographic bone density (RD) and fractal dimension analysis. Radiographic bone density mean values (SD), expressed as aluminum equivalent in mm, of AB, BG, AB + LP-PRP, and BG + LP-PRP groups were 1.79 (0.31), 2.04 (0.39), 1.61 (0.28), and 1.53 (0.30), respectively. Significant differences (P < 0.05) were observed between BG and AB, and BG + PRP and BG. Fractal dimension mean values were 1.48 (0.04), 1.35 (0.08), 1.44 (0.04), and 1.44 (0.06), respectively. Significant differences were observed between BG and AB, and AB + LP-PRP and BG. Mean values for the percentage of bone inside MS were 63.30 (8.60), 52.65 (10.41), 55.25 (7.01), and 51.07 (10.25), respectively. No differences were found. No correlations were observed among percentage of bone, RD and FD. Histological analysis showed that MS treated with AB presented mature and new bone formation. The other groups showed minor bone formation. Within the limitations of this study, the results indicated that at a 90-day time end point, AB yielded better results than AB + LP-PRP, BG, and BG + LP-PRP and should be considered the primary material for MS augmentation.

Comparison between embossed digital imaging and unprocessed film-based radiography in detecting periodontal bone defects: an in vitro study

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Effect of Combined Digital Imaging Parameters on Endodontic File Measurements

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effect of metal conditioners on the adhesive bonding of resin cements to cast titanium

Objective: To assess the effect of metal conditioners on the bond strength between resin cements and cast titanium. Method and Materials: Commercially pure titanium (99.56%) was cast using an arc casting machine. Surfaces were finished with 400-grit silicon carbide paper followed by air abrasion with 50-mu m aluminum oxide. A piece of double-coated tape with a 4-mm circular hole was then positioned on the metal surface to control the area of the bond. The prepared surfaces were then divided into 4 groups (n=10): G1, unprimed Panavia F; G2, Alloy Primer-Panavia F; G3, unprimed Bistite DC; G4, Metaltite-Bistite DC. Forty minutes after insertion of the resin cements, the specimens were detached from the mold and stored in water at 37 C for 24 hours. Shear bond strength was performed in a testing machine (MTS 810) at a crosshead speed of 0.5 mm/min. Data were analyzed using ANOVA and Tukey's test with a .05 significance level. The fractured surfaces were observed through an optical microscope at 10x magnification. Results: the G1 group demonstrated significantly higher shear bond strength (17.95 MPa) than the other groups. G3 (13.79 MPa) and G4 (12.98 MPa) showed similar mean values to each other and were statistically superior to G2 (9.31 MPa). Debonded surfaces generally presented adhesive failure between metal surfaces and resin cements. Conclusion: While the Metaltite conditioner did not influence the bond strength of the Bistite DC cement, the Alloy Primer conditioner significantly decreased the mean bond strength of the Panavia F cement.

Hardness of heat-polymerized acrylic resins after disinfection and long-term water immersion

Statement of the problem. In selecting a disinfectant for dental prostheses, compatibility between the disinfectant and the type of denture base material must be considered to avoid adverse effects on the hardness of the acrylic resin.Purpose. This study investigated the hardness of 2 denture base resins after disinfection and long-term water immersion.Material and methods. Thirty-two disk-shaped specimens (13 mm in diameter and 8 mm thick) were fabricated from each resin (Lucitone 550 and QC-20), polished, stored in water at 37degreesC for 48 hours, and submitted to hardness tests (Vickers hardness number [VHN]) before disinfection. Disinfection methods included scrubbing with 4% chlorhexidine gluconate for 1 minute, immersion for 10 minutes in I of the tested disinfectant Solutions (n=8) (3.78% sodium perborate, 4% chlorhexidine gluconate, or 1% sodium hypochorite), and immersion in water for 3 minutes. The disinfection procedures were repeated 4 times, and 12 hardness measurements were made on each specimen. Control specimens (not disinfected) were stored in water for 56 minutes. Hardness tests (VHN) were also performed after 15, 30, 60, 90, and 120 days of storage in water. Statistical analyses of data were conducted with a repeated measures 3-way analysis of variance (ANOVA) and Tukey post-hoc test (alpha=.05).Results. Mean values +/- SD for Lucitone 550 (16.52 +/- 0.94 VHN) and QC-20 (9.61 +/- 0.62 VHN) demonstrated a significant (P<.05) decrease in hardness after disinfection, regardless of material and disinfectant solutions used (Lucitone 550: 15.25 +/- 0.74; QC-20: 8.09 +/- 0.39). However, this effect was reversed after 15 days of storage in water. Both materials exhibited a continuous increase (P<.05) in hardness values for up to 60 days of water storage, after which no significant change was observed.Conclusion. Within the limitations of this in vitro study, QC-20 and Lucitone 550 specimens exhibited significantly lower hardness values after disinfection regardless of the disinfectant solution used.

Effect of microwave irradiation and water storage on the viscoelastic properties of denture base and reline acrylic resins

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Flexural strength and hardness of reline and denture base acrylic resins after different exposure times of microwave disinfection

Objectives: To evaluate the effect of microwave disinfection on the flexural strength and Vickers hardness of 4 autopolymerized resins (Kooliner [K], Tokuso Rebase Fast [T], Ufi Gel Hard [U], and New Truliner [N]) and 1 denture base resin (Lucitone 550 [L]). Method and Materials: For each material, 48 specimens (64 x 10 x 3.3 mm) were made and divided into 6 equal groups (n = 8). In the control group, specimens were untreated. Before testing, specimens were immersed in 200 mL of distilled water and submitted to disinfection for 1 of the following irradiation times: 1, 2, 3, 4, or 5 minutes. The irradiation procedure was performed twice. The flexural strength was determined using a testing machine MTS-810 and measurements of Vickers hardness were made on Micromet 2100. The values were submitted to ANOVA and Tukey's test (P = .05). Results: The K material showed a significant increase (P = .0010) in flexural strength following 5 minutes of disinfection compared to control specimens. The flexural strength mean values of materials T, U, and N were not significantly affected (P > .05) by disinfection. Compared to the control group, the K material showed a significant increase in hardness (P < .001) following disinfection for 3, 4, and 5 minutes. For material U, disinfection for 4 and 5 minutes produced specimens with significantly increased hardness values (P < .001) compared to the control group. For material N, disinfection for 5 minutes resulted in significantly higher hardness values (P < .001) than the control group. Conclusion: Regardless of the irradiation time, the flexural strength and hardness of the materials evaluated were not detrimentally affected by microwave disinfection. (Quintessence Int 2008;39:833-840)

Effect of long-term water immersion on the fracture toughness of denture base and reline resins

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

The Effect of Splint Material Rigidity in Implant Impression Techniques

Purpose This in vitro study compared the dimensional accuracy of two impression techniques Duralay splinted impression copings (D) and metal splinted impression copings (M) for implant supported pros theses Materials and Methods A master cast with four parallel implant abutment analogs and a passive framework were fabricated Vinyl polysiloxane impression material was used for all impressions with a metal stock tray Two groups (D and M) were tested (n = 5) The measurement method employed was just one titanium screw tightened to the framework Each group s measurements were analyzed using software that received the images of a video camera coupled to a stereomicroscope at X100 magnification The results were analyzed statistically (t test) Results The mean values of abutment/framework interface gaps were master cast = 32 mu m (SD 2), group D = 165 mu m (SD 60), and group M = 69 mu m (SD 36) There was a statistically significant difference between the D and M groups (P <= 001) Conclusion Under the limitations of this study, it could be suggested that a more accurate working cast can be fabricated using metal splinted impression copings INT J ORAL MAXILLOFAC IMPLANTS 2010 25 1153-1158

THE EFFECT of DIFFERENT SURFACE TREATMENTS on THE SHEAR BOND STRENGTH of LUTING CEMENTS TO TITANIUM

Statement of problem. Although titanium presents attractive physical and mechanical properties, there is a need for improving the bond at the titanium/luting cement interface for the longevity of metal ceramic restorations.Purpose. The purpose of this study was to evaluate the effect of surface treatments on the shear bond strength (SBS) of resin-modified glass ionomer and resin cements to commercially pure titanium (CP Ti).Material and methods. Two hundred and forty CP Ti cast disks (9.0 x 3.0 mm) were divided into 8 surface treatment groups (n=30): 1) 50 mu m Al2O3 particles; 2) 120 mu m Al2O3 particles; 3) 250 mu m Al2O3 particles; 4) 50 mu m Al2O3 particles + silane (RelyX Ceramic Primer); 5) 120 mu m Al2O3 particles + silane; 6) 250 mu m Al2O3 particles + silane; 7) 30 mu m silica-modified Al2O3 particles (Cojet Sand) + silane; and 8) 120 mu m Al2O3 particles, followed by 110 mu m silica-modified Al2O3 particles (Rocatec). The luting cements 1) RelyX Luting 2; 2) RelyX ARC; or 3) RelyX U100 were applied to the treated CP Ti surfaces (n=10). Shear bond strength (SBS) was tested after thermal cycling (5000 cycles, 5 degrees C to 55 degrees C). Data were analyzed by 2-way analysis of variance (ANOVA) and the Tukey HSD post hoc test (alpha=.05). Failure mode was determined with a stereomicroscope (x20).Results. The surface treatments, cements, and their interaction significantly affected the SBS (P<.001). RelyX Luting 2 and RelyX U100 exhibited similar behavior for all surface treatments. For both cements, only the group abraded with 50 mu m Al2O3 particles had lower SBS than the other groups (P<.05). For RelyX ARC, regardless of silane application, abrasion with 50 mu m Al2O3 particles resulted in significantly lower SBS than abrasion with 120 mu m and 250 mu m particles, which exhibited statistically similar SBS values to each other. Rocatec + silane promoted the highest SBS for RelyX ARC. RelyX U100 presented the highest SBS mean values (P<.001). All groups showed a predominance of adhesive failure mode.Conclusions. The adhesive capability of RelyX Luting 2 and RelyX U100 on the SBS was decisive, while for RelyX ARC, mechanical and chemical factors were more influential. (J Prosthet Dent 2012;108:370-376)

Fracture strength of flared bovine roots restored with different intraradicular posts

Objective: The aim of this study was to evaluate the fracture strength and failure mode of flared bovine roots restored with different intraradicular posts. Material and Methods: Fifty bovine incisors with similar dimensions were selected and their roots were flared until 1.0 mm of dentin wall remained. Next, the roots were allocated into five groups (n=10): GI-cast metal post-and-core; GII-fiber posts plus accessory fiber posts; GIII-direct anatomic post; GIV-indirect anatomic post and GV-control (specimens without intraradicular post). A polyether impression material was used to simulate the periodontal ligament. After periodontal ligament simulation, the specimens were subjected to a compressive load at a crosshead speed of 0.5 mm/min in a servo-hydraulic testing machine (MTS 810) applied at 135 to the long axis of the tooth until failure. The data (N) were subjected to ANOVA and Tukey's post-hoc test (alpha=0.05). Results: GI and GIV presented higher fracture strength (p<0.05) than GII. GIII presented intermediate values without statistically significant differences (p>0.05) from GI, GII and GIV. Control specimens (GV) produced the lowest fracture strength mean values (p<0.05). Despite obtaining the highest mean value, GI presented 100% of unfavorable failures. GII presented 20% of unfavorable failures. GIII, GIV and GV presented only favorable failures. Conclusions: Although further in vitro and in vivo studies are necessary, the results of this study showed that the use of direct and indirect anatomic posts in flared roots could be an alternative to cast metal post-and-core.

Comparison of impression techniques and materials for implant-supported prosthesis

Purpose: To investigate, in vitro, the dimensional accuracy of two impression techniques (squared impression copings and squared impression copings sandblasted and coated with impression adhesive) made of vinyl polysiloxane and polyether impression materials. Materials and Methods: A master cast (control group) with four parallel implant abutment analogs, a passive framework, and a custom aluminum tray was fabricated. Four groups (n = 5 each group) were tested: squared Impregum (SI), squared Express (SE), sandblasted adhesive squared Impregum (ASI), and sandblasted adhesive squared Express (ASE). The measurement method employed was just one titanium screw tightened to the framework. A stereomicroscope was used to evaluate the fit of the framework by measuring the size of the gap between the abutment and the framework. The results were analyzed statistically. Results: The mean values for the abutment/framework interface gaps were: master cast, 31.63 mu m (SD 2.16); SI, 38.03 mu m (SD 9.29); ASI, 46.80 mu m (SD 8.47); SE, 151.21 mu m (SD 22.79); and ASE, 136.59 mu m (SD 29.80). No significant difference was detected between the SI or ASI techniques and the master cast. No significant difference was detected between the SE and ASE techniques. Conclusion: Within the limitations of this study, it can be concluded that Impregum Soft medium consistency was the best impression material and the impression technique did not influence the accuracy of the stone casts. INT J ORAL MAXILLOFAC IMPLANTS 2010;25:771-776

Influence of surface treatments on the flexural strength of denture base repair

Objective: The purpose of this study was to evaluate the flexural strength of repairs made with autopolymerising acrylic resin after different treatments of joint surfaces.Material and Methods: Fifty rectangular specimens were made with heat-polymerised acrylic resin and 40 were repaired with autopolymerising acrylic resin following joint surface treatments: group 1 (intact specimens), group 2 (chemical treatment: wetting with methyl-methacrylate for 180 s), group 3 (abraded with silicon carbide paper), group 4 (abraded and wetting with methyl-methacrylate for 180 s) and group 5 (without surface treatment). The flexural strength was measured by a three-point bending test using a universal testing machine with a 100 Kgf load cell in the centre of repair at 5 mm/min cross-head speed. All data were analysed using one-way ANOVA and Tukey HSD test for multiple comparisons (p < 0.05).Results: Among repaired specimens, groups 2 and 4 had 66.53 +/- 3.4 and 69.38 +/- 1.8 MPa mean values and were similar. These groups had superior flexural strength than groups 3 and 5 that were similar and had 54.11 +/- 3.4 and 51.24 +/- 2.8 MPa mean values, respectively. Group 1 had a mean value of 108.30 +/- 2.8 MPa being the highest result.Conclusion: It can be concluded that the treatment of the joint surfaces with methyl-methacrylate increases the flexural strength of denture base repairs, although the strength is still lower than that observed for the intact denture base resin. Abrasion with sandpaper was not able to influence the flexural strength of repaired denture bases.