Effect of Surface Treatment With Er:YAG and CO2 Lasers on Shear Bond Strength of Polyether Ether Ketone to Composite Resin Veneers

Introduction: Polyether ether ketone (PEEK) has low surface energy and high resistance to chemical surface treatments. Therefore, different surface treatments such as laser conditioning should be investigated. There is a gap of information regarding the efficacy of laser irradiation in the surface treatment of PEEK, and the efficacy of several laser types needs to be evaluated for this purpose. This study aimed to assess the effect of surface treatment with erbium-doped yttrium aluminum garnet (Er:YAG) and carbon dioxide (CO2) lasers on shear bond strength (SBS) of PEEK to composite resin veneers.Methods: In this experimental study, 60 rectangular-shaped PEEK samples (7 x 7 x 2 mm) were used. The samples were mounted in auto-polymerizing acrylic resin in such a way that only one surface measuring 7x7 mm remained exposed. The samples were then randomly divided into 3 groups (n = 20) of control, Er:YAG laser surface treatment (Power = 1.5 W, energy density = 119.42 J/cm2, irradiation time = 20 s) and CO2 laser surface treatment (Power = 4 W, energy density = 159.22 J/cm2, irradiation time = 50 s). The bonding agent and PEEK opaque were applied on the surface of samples and they were veneered with a composite resin using a hollow plastic cylinder with an internal diameter of 4 mm. The SBS was then measured and the data were analyzed using one-way ANOVA, Tukey HSD test and Dunnett’s test at 0.05 level of significance.Results: The SBS of the 3 groups was significantly different (P < 0.001). The Tukey HSD test revealed that the Er:YAG laser had higher SBS than the CO2 laser group (P < 0.001). The Dunnett’s test showed that both Er:YAG and CO2 laser groups yielded higher SBS than the control group (P < 0.001).Conclusion: The Er:YAG and CO2 laser treatments can increase the SBS of PEEK to composite resin veneers, although the Er:YAG laser seems to be more effective for this purpose.

Effect of different mechanical surface treatments on flexural strength of repaired denture base.

Aim: To assess the effect of different mechanical surface treatments on flexural strength of repaired denture base. Material and Methods: Sixty bar-shaped specimens of heat-polymerized acrylic resin were fabricated, and divided into six groups (n=10). All specimens, except the positive control group (group PC), were sectioned into halves to create a 1-mm clearance. A negative control group with no surface treatment (group NC) was also considered. Other groups underwent different surface treatments: group Laser; treated with erbium: yttrium-aluminum-garnet (Er:YAG) laser, group APA; airborne-particle abrasion (APA), group APA plus Laser; a combination of laser and APA, and group Bur; bur grinding. After measuring surface roughness (Ra) with a profilometer, all sectioned specimens were repaired by auto-polymerizing acrylic resin, and thermocycled afterward. Three-point bending test was performed by a universal testing machine. Data were statistically analyzed (α=0.05). Results: The mean surface roughness of all experimental groups were significantly higher than that of group NC (p<0.05). The mean flexural strength of all groups was significantly lower than that of group PC (p<0.05). Group B had significantly higher flexural strength than the other surface-treated groups (p<0.05). Group Laser had significantly higher flexural strength than groups APA (p=0.043) and APA plus Laser (p=0.023). No significant difference was found between groups APA and APA plus Laser (p=0.684). Conclusion: All surface treatments increased the surface roughness and flexural strength compared with the untreated group. The highest flexural strength was observed in specimens treated by bur grinding and then laser, however, it was still significantly lower than intact specimens

Full Mouth Reconstruction of a Skeletal Class II Division 1 Patient with Adenoid Cystic Carcinoma Using an Interim Immediate Obturator and a Definitive Obturator

A 61-year-old female patient with adenoid cystic carcinoma (ACC) of the right maxilla and Angle class II division 1 malocclusion had received a subtotal maxillectomy in right side and used a conventional clasp-retained obturator. After implants placement, a maxillary interim immediate obturator (IIO) and then a definitive obturator using six endosseous implants were fabricated. During one-year follow-up, the patient was completely satisfied. Ideally, after implants placement in edentulous patients suffering from hemimaxillectomy, an implant-supported obturator (ISO) is designed in order to prevent nasal reflux and to improve speech and swallowing. However, in the following case, because of skeletal class II division 1 malocclusion and implants insertion in the premaxilla, using an ISO was impossible because it would cause excessive upper lip protrusion and lack of anterior teeth contact. Therefore, a five-unit implant-supported fixed partial denture (FPD) was fabricated in the maxillary anterior segment so that anterior teeth contacts were possible and the patient’s normal lip support was achieved. A bar and three ball attachments were used in the maxillary posterior segment. A closed-hollow-bulb ISO was preferred. Conventional ISO in these patients results in several problems. Using a maxillary anterior FPD along with ISO caused satisfactory results in the current patient

Prosthetic rehabilitation of a mandibular root amputated molar using single crown

In teeth with furcation involvement, root amputation is one of the treatment choices. A challenge which a dentist may encounter with is the prosthetic treatment of such teeth when their adjacent teeth are intact. According to the current goal of operative dentistry based on conservative treatment, it would be desirable to do in a manner resulting in minimal damage to the adjacent sound teeth. In the following case report, a step-by-step conservative treatment sequences of a mandibular molar with distal root amputation which not involving surrounding teeth is described. During 18 months follow-up, the results were satisfactory

Marginal adaptation of three-unit interim restorations fabricated by the CAD-CA systems and the direct method before and after thermocycling

Limited information is available regarding the marginal adaptation of three-unit interim restorations fabricated by different techniques from different materials. Also, the efficacy of computer-aided design/computer-aided manufacturing (CAD-CAM) systems

Shear bond strength of different luting agents to polyether ether ketone

Background: Polyether ether ketone (PEEK) was recently introduced to dentistry. However, difficulty in provision of a strong durable bond is its main drawback. Thus, precise surface treatment and use of a suitable luting agent are imperative for bonding of PEEK restorations. This study aimed to assess the effect of type of luting agent on shear bond strength (SBS) of PEEK. Materials and Methods: In this in vitro study, 60 square-shaped PEEK samples were fabricated and sandblasted with 110 μm Al2O3 particles. The samples were then divided into four groups based on the type of cement used (n = 15): zinc phosphate cement, Panavia F2, Panavia V5, and resin-modified glass-ionomer (RMGI) cement. After bonding, the samples were thermocycled for 5000 cycles. The SBS was measured by a universal testing machine. The surface of samples was inspected under a video measuring machine to determine the mode of failure. Data were analyzed using the Kruskal–Wallis test via SPSS version 24 (α = 0.05). Results: RMGI did not bond to PEEK. The SBS values were 4.02 ± 2.87 megapascals (MPa) for Panavia V5, 10.84 ± 6.05 MPa for Panavia F2, and 10.50 ± 2.88 MPa for zinc phosphate. The SBS in the Panavia V5 group was significantly lower than that in the Panavia F2 (P = 0.001) and zinc phosphate (P 0.05). Conclusion: Panavia F2 resin cement and zinc phosphate conventional cement provided the highest bond strength to PEEK, while RMGI did not bond to PEEK

Use of Digital-Conventional Method for Managing a Patient with Severely Worn Dentition: A Clinical Report

Severe forms of attrition are frequently found in patients with no or insufficient posterior occlusal support. Management of such patients using fixed or removable prostheses is a complex procedure and is still a challenge for clinicians. The present clinical report describes step by step full mouth rehabilitation of a patient with severely worn dentition using computer-aided design/computer-aided manufacturing- (CAD/CAM-) generated wax patterns, milled zirconia frameworks, and fabrication of removable partial denture (RPD) abutments using a digital-conventional method. The results were satisfactory during 18 months of follow-up

Marginal and internal fit and fracture resistance of three‐unit provisional restorations fabricated by additive, subtractive, and conventional methods

Abstract Objectives To compare the marginal and internal fit and fracture resistance of three‐unit provisional fixed dental prostheses (FDPs) fabricated by additive, subtractive, and conventional methods. Material and Methods Eighty 3‐unit FDPs were fabricated on metal dies of the maxillary right second premolar and second molar by four different techniques (n = 20): The direct method by using autopolymerizing polymethyl methacrylate (PMMA), indirect method by the compression molding technique, subtractive manufacturing by using PMMA blocks, and additive manufacturing by using digital light processing technology. The adaptation of restorations at the marginal, axial, cuspal, and fossa areas was assessed by using the silicone replica technique. After thermocycling and cyclic loading, the fracture resistance was measured by a universal testing machine. Data were analyzed by a two‐way analysis of variance (ANOVA), ANOVA, and Tukey test (α = .05). Results The mean gap measured in the additive group was lower than that in all other groups at all points (p < .05); however, the difference in the marginal gap with the subtractive group was not significant (p = .995). The mean marginal and axial gaps in the subtractive group were significantly lower than the corresponding values in both conventional groups (p < .05). A significant difference existed between all groups regarding the mean cuspal and fossa gaps (p < .05). The mean fracture resistance of the additive group was significantly higher than that of indirect (p = .018) and direct (p < .001) groups, and the fracture resistance of the subtractive group was significantly higher than that of the direct group (p = .020). Conclusion The digitally fabricated provisional FDPs showed superior marginal and internal fit and higher fracture resistance than the conventionally fabricated FDPs. Between the digital methods, the additive technique yielded superior internal fit