Fracture Resistance of Pressed and Milled Lithium Disilicate Anterior Complete Coverage Restorations Following Endodontic Access Preparation.

PURPOSE: This in vitro study evaluated the fracture resistance and clinical prognosis of anterior lithium disilicate crowns (e.max Press and e.max CAD), following endodontic access and repair. The research design simulates intraoral loading conditions to produce clinically applicable results. MATERIALS AND METHODS: Monolithic anterior crowns, based on #8 anatomy, were fabricated from e.max Press ingots and e.max CAD blocks and adhesively bonded on identical dies milled out of a dentin analog material (NEMA G10). Specimens were divided into 4 groups: intact pressed, repaired pressed, intact milled, and repaired milled (n = 15/group). Repaired pressed and repaired milled were prepared with a standardized endodontic access and repaired using a porcelain repair system and composite resin. All crowns were cyclically loaded under simulated oral conditions and then loaded to failure in water, using a universal testing machine. Data were interpreted using ANOVA/Tukey post-hoc test (α = 0.05). RESULTS: Mean loads to failure ranged from 758.9 to 931.4 N for the 4 groups, indicating that both fabrication techniques, pressed and milled, yielded restorations that could reasonably withstand maximum masticatory forces. The pressed groups (923.7 N) exhibited significantly higher fracture resistance than the milled groups (797.5 N), p = 0.0002. When milled and pressed groups were categorized into intact and repaired subgroups, no difference was found in fracture resistance between the subgroups. Differences were noted in the modes of fracture, where the milled groups (intact and repaired) exhibited higher frequency of catastrophic fractures than the pressed groups. CONCLUSIONS: Endodontic access preparation does not appear to affect fracture resistance of an anterior lithium disilicate restoration, suggesting that replacement may not be necessary. Fabrication technique had a significant effect on fracture resistance and fracture mode of lithium disilicate restorations. The pressed fabrication technique resulted in significantly greater crown strength and fracture resistance than the milled technique.

Marginal discrepancy of noble metal-ceramic fixed dental prosthesis frameworks fabricated by conventional and digital technologies.

STATEMENT OF PROBLEM: Studies evaluating the marginal adaptation of available computer-aided design and computer-aided manufacturing (CAD-CAM) noble alloys for metal-ceramic prostheses are lacking. PURPOSE: The purpose of this in vitro study was to evaluate the vertical marginal adaptation of cast, milled, and direct metal laser sintered (DMLS) noble metal-ceramic 3-unit fixed partial denture (FDP) frameworks before and after fit adjustments. MATERIAL AND METHODS: Two typodont teeth were prepared for metal-ceramic FDP abutments. An acrylic resin pattern of the prepared teeth was fabricated and cast in nickel-chromium (Ni-Cr) alloy. Each specimen group (cast, milled, DMLS) was composed of 12 casts made from 12 impressions (n=12). A single design for the FDP substructure was created on a laboratory scanner and used for designing the specimens in the 3 groups. Each specimen was fitted to its corresponding cast by using up to 5 adjustment cycles, and marginal discrepancies were measured on the master Ni-Cr model before and after laboratory fit adjustments. RESULTS: The milled and DMLS groups had smaller marginal discrepancy measurements than those of the cast group (P<.001). Significant differences were found in the number of adjustments among the groups, with the milled group requiring the minimum number of adjustments, followed by the DMLS and cast groups (F=30.643, P<.001). CONCLUSIONS: Metal-ceramic noble alloy frameworks fabricated by using a CAD-CAM workflow had significantly smaller marginal discrepancies compared with those with a traditional cast workflow, with the milled group demonstrating the best marginal fit among the 3 test groups. Manual refining significantly enhanced the marginal fit of all groups. All 3 groups demonstrated marginal discrepancies within the range of clinical acceptability.

An accessory technique for the intraoral removal of a fractured implant abutment screw.

As the use of dental implants becomes more prevalent, mechanical complications become more common. When an implant abutment screw fractures, it can be difficult to retrieve the retained fragment. The purpose of this article is to describe a technique to remove the abutment screw fragments without damaging the implant body or its screw threads.

Effect of surface treatments on repair with composite resin of a partially monoclinic phase transformed yttrium-stabilized tetragonal zirconia.

STATEMENT OF PROBLEM: Studies of composite resin repairs of yttrium-tetragonal zirconia polycrystal (Y-TZP) are usually performed in its tetragonal phase, but it may be partially transformed into a monoclinic phase in a clinical fracture. PURPOSE: The purpose of this in vitro study was to evaluate the effect of airborne-particle abrasion (APA) and a bonding agent on the shear bond strength (SBS) between a composite resin and hydrothermally aged Y-TZP. MATERIAL AND METHODS: Specimens (7.0×7.0×1.7 mm, N=112) of Y-TZP Lava were obtained, and 50% were aged in an autoclave at 134°C at 300 kPa for 8 hours. The surfaces were treated with APA 50-µm Al2O3 particles (ALU) or Rocatec Soft (30 µm) (ROC) followed by Clearfil SE Bond Primer (10-methacryloyloxydecyl dihydrogen phosphate [10-MDP]) plus Clearfil porcelain bond activator (3-methacryloxypropyl-trimethoxy silane [3-MPS]) (CLE) or RelyX Ceramic Primer plus a layer of RelyX U100 adhesive-resin cement (REL). Composite resin cylinders were built on the Y-TZP treated surfaces. After thermocycling (6000 cycles, 5°C and 55°C, 30-second dwell time), an SBS test was carried out (n=14). Data were analyzed by 3-way ANOVA and the Tukey honest significant differences test (α=.05). The failure mode was analyzed. RESULTS: The 3-way ANOVA was not significant for aging (P>.05), but the APA (P<.001), bonding agent (P<.001), and their interaction (P<.001) were significant. APA with ALU or ROC did not influence the SBS of the groups bonded with CLE, but the REL APA with ROC provided higher SBS. The failure mode was adhesive for all specimens. CONCLUSIONS: Adhesion was not different on monoclinic partially transformed Y-TZP. The APA with ROC followed by REL was the most effective treatment for repairing Y-TZP.

Clinical assessment of fractured implant abutment screws: The Bernese silicone replica technique.

Fractured implant abutment screws can be retrieved with repair or rescue devices. However, whether the screw was completely retrieved or the inner implant body was damaged may be uncertain. A silicone replica technique was recently implemented in Bern and may be the most predictable method available at the moment for clinically assessing the internal implant body. This technique is straightforward and precise and may help dentists determine the internal implant condition when managing a fractured screw.

Management of a Damaged Implant for Retention of an Overdenture Prosthesis and Fixed Single Crown: Clinical Reports.

This article demonstrates a method to salvage an implant that has been damaged or is no longer usable because of a fractured screw that cannot be removed. In the first situation the patient had a Locator abutment that fractured during torqueing of the abutment. Despite the attempt to remove the fractured screw, it was not retrievable, and the internal threads of the implant were damaged in the attempt to remove the screw. Rather than removing the implant or covering it and sleeping the implant, a custom cast post was used to restore the implant to function. A second example describes a patient with a fixed implant crown. The implant was damaged during attempts to remove the fractured screw. A custom post was fabricated and cemented, and a new crown was fabricated.

In Vitro Comparison of the Bond Strength between Ceramic Repair Systems and Ceramic Materials and Evaluation of the Wettability.

PURPOSE: When fracture of an all-ceramic restoration occurs, it can be necessary to repair without removing the restoration. Although there are many studies about the repair of metal-ceramic restorations, there are few about all-ceramic restorations. The aim of this study was to evaluate the shear bond strength between ceramic repair systems and esthetic core materials and to evaluate the wettability of all-ceramic core materials. MATERIALS AND METHODS: Disk-like specimens (N = 90) made of three dental ceramic infrastructure materials (zirconia ceramic, alumina ceramic, glass ceramic) were polished with silicon carbide paper, prepared for bonding (abrasion with 30 µm diamond rotary cutting instrument). Thirty specimens of each infrastructure were obtained. Each infrastructure group was divided into three subgroups; they were bonded using 3 repair systems: Bisco Intraoral Repair Kit, Cimara & Cimara Zircon Repair System, and Clearfil Repair System. After 1200 thermocycles, shear bond strength was measured in a universal testing machine at a 0.5 mm/min crosshead speed. In addition, the contact angle values of the infrastructures after surface treatments were examined for wettability. Data were analyzed by using ANOVA and Tukey post hoc tests. RESULTS: Although there were no significant differences among the repair systems (p > 0.05) in the glass ceramic and zirconia groups, a significant difference was found among the repair systems in alumina infrastructure (p < 0.001). There were no statistically significant differences among the infrastructures (p > 0.05); however, a statistically significant difference was found among the repair systems (p < 0.05). No difference was found among the infrastructures and repair systems in terms of contact angle values. CONCLUSIONS: Cimara & Cimara Zircon Repair System had higher bond strength values than the other repair systems. Although no difference was found among the infrastructures and repair systems, contact wettability angle was decreased by surface treatments compared with polished surfaces.

Ceramic Repair Without Hydrofluoric Acid.

PURPOSE: To evaluate the bond strength between composite resin and feldspathic ceramic following repair protocols with and without hydrofluoric acid and aging by thermocycling. MATERIALS AND METHODS: Forty-eight glass feldspathic ceramic blocks (8 x 8 x 6 mm) were divided into three groups on the basis of their surface repair treatment: 1. 10% hydrofluoric acid + Signum Ceramic Primer I + Signum Ceramic Primer II (control group); 2. abrasive rubber tips + Signum Ceramic Primer I + Signum Ceramic Primer II (test group); 3. Signum Ceramic Primer I + Signum Ceramic Primer II (negative control group). The treated surface of each block was built up with composite and then sectioned to produce nontrimmed bars (adhesive area = 1 mm²). Half of the bars from each group were aged by 6000 cycles of 30-s immersions in water baths at 5°C and 55°C, with a transfer time of 2 s. The other bars were immediately subjected to microtensile bond strength testing. The mean bond strength for each block was then recorded and submitted to two-way ANOVA and Tukey's test (α = 0.05). RESULTS: The aging protocol influenced the bond strength values of all groups (p = 0.000). The non-aged groups submitted to surface treatment protocols 1 (13.1 ± 2.5 MPa) and 2 (11.5 ± 5.1 MPa) presented the highest bond strength values. CONCLUSIONS: The interface bond strength of all groups was susceptible to aging. Surface treatment protocol 2, with abrasive rubber tips and no hydrofluoric acid, appeared to be the most promising option, as the resulting bond strength values were similar to those of the control group.

Prospective assessment of CAD/CAM zirconia abutment and lithium disilicate crown restorations: 2.4 year results.

STATEMENT OF PROBLEM: Single-tooth implant restorations are commonly used to replace anterior maxillary teeth. The esthetic, functional, and biologic outcomes are, in part, a function of the abutment and crown. PURPOSE: The purpose of this clinical study was to describe the implant, abutment, and crown survival and complication rates for CAD/CAM zirconia abutment and lithium disilicate crown restorations for single-tooth implants. MATERIAL AND METHODS: As part of a broader prospective investigation that enrolled and treated 141 participants comparing tissue responses at the conical interface (CI; AstraTech OsseoSpeed), flat-to-flat interface (FI; NobelSpeedy), and platform-switch interface (PS; NanoTite Certain Prevail) of single-tooth implants, computer-aided design and computer-aided manufacturing (CAD/CAM) zirconia abutments (ATLANTIS Abutment) and cemented lithium disilicate (e.max) crowns were used in the restoration of all implants. After 2.4 years in function (3 years after implant placement), the implant, abutment, and crown of 110 participants were evaluated. Technical and biologic complications were recorded. Demographic results were tabulated as percentages with mean values and standard deviations. Abutment survival was calculated with the Kaplan-Meier method. RESULTS: After 2.4 years, no abutments or crowns had been lost. Abutment complications (screw loosening, screw fracture, fracture) were absent for all 3 implant groups. Crown complications were limited to 2 crowns debonding and 1 with excess cement (2.5%). Five biological complications (4.0%) were recorded. The overall complication rate was 6.5%. CONCLUSIONS: CAD/CAM zirconia abutments restored with cemented lithium disilicate crowns demonstrated high survival on 3 different implant-abutment interface designs. No abutment or abutment screw fracture occurred. The technical complications observed after 2.4 years were minor and reversible. The use of CAD/CAM zirconia abutments with cemented lithium disilicate crowns is associated with high technical and biologic success at 2.4 years.

Survival of cast-metal, resin-bonded fixed partial dental prostheses after nearly 20-year follow-up: A retrospective study.

STATEMENT OF PROBLEM: Cast-metal resin-bonded fixed partial dental prostheses (RBFPDPs) are a conservative approach to replacing missing teeth. Despite their recognized advantages, the use of cast-metal RBFPDPs as a definitive option remains somewhat controversial because of the lack of long-term studies on their success. PURPOSE: The purpose of this retrospective study was to evaluate the long-term survival rate of cast-metal RBFPDPs and investigate the influence of covariates such as sex, type of prosthesis, location, number of pontics, abutments, and type of luting cement on the survival of bonded prostheses. MATERIAL AND METHODS: This study evaluated 209 cast-metal RBFPDPs cemented in 181 patients (mean 41.06 ±11.90 years of age) treated in the principal author's private practice between July 1993 and May 2012. Data sheets were completed at the patients' recall examination at regular intervals or if seen for complications. Kaplan-Meier analysis was used to evaluate the survival rate of the prostheses before debonding. The Cox model and Wald test were used to analyze the prognostic factors (α=.05). RESULTS: A total of 198 prostheses were studied. Eleven cast-metal RBFPDPs were lost to follow-up. This study evaluated the effect of different variables on the survival rate of both conventional RBFPDPs (wing-wing) and combination resin-bonded FPDPs (wing-crown) types. Survival rate was divided into "with repair" and "without repair" groups. The mean survival time was 102.24 months for the group with no repair and 119.76 months for the group with repair. The survival rate after 5, 10, and 15 years was 86%, 42%, and 15% with repair, whereas 69%, 32%, and 14% of the prostheses survived without repair. CONCLUSIONS: In appropriate clinical conditions and selected patients, cast-metal RBFPDPs were a viable treatment option with an acceptable survival rate.

A minimally invasive approach for a compromised treatment plan.

A primary goal in dentistry is the execution of appropriate treatment plans that are minimally invasive and maintainable. However, it is sometimes necessary to repair existing dental restorations or revise treatment plans to accommodate changes in a patient's condition. In the present case, a patient who was satisfied with a removable partial overdenture lost a critical abutment tooth. A creative, minimally invasive approach enabled the patient to keep his existing partial prosthesis and avoid the need for a full reconstruction or complete denture.

Efficacy of ceramic repair material on the bond strength of composite resin to zirconia ceramic.

OBJECTIVE: The aim of this study was to evaluate the shear bond strength of composite resin in five different repair systems. MATERIALS AND METHODS: Sixty specimens (7 mm in diameter and 3 mm in height) of zirconia ceramic were fabricated. All specimen surfaces were prepared with a 30 µm fine diamond rotary cutting instrument with water irrigation for 10 s and dried with oil-free air. Specimens were then randomly divided into six groups for the following different intra-oral repair systems (n = 10): Group 1, control group; Group 2, Cojet system (3M ESPE, Seefeld, Germany); Group 3, Cimara® System (Voco, Cuxhaven, Germany); Group 4, Z-Prime Plus System (Bisco Inc., Schaumburg, IL); Group 5, Clearfil™ System (Kuraray, Osaka, Japan); and Group 6, Z-Bond System (Danville, CA). After surface conditioning, a composite resin Grandio (Voco, Cuxhaven, Germany) was applied to the zirconia surface using a cylindrical mold (5 mm in diameter and 3 mm in length) and incrementally filled up, according to the manufacturer's instructions of each intra-oral system. Each specimen was subjected to a shear load at a crosshead speed of 1 mm/min until fracture. One-way analysis of variance (ANOVA) and Tukey post-hoc tests were used to analyze the bond strength values. RESULTS: There were significant differences between Groups 2-6 and Group 1. The highest bond strength values were obtained with Group 2 (17.26 ± 3.22) and Group 3 (17.31 ± 3.62), while the lowest values were observed with Group 1 (8.96 ± 1.62) and Group 6 (12.85 ± 3.95). CONCLUSION: All repair systems tested increased the bond strength values between zirconia and composite resin that used surface grinding with a diamond bur.

Technique to retrieve implant abutment fragments.

This clinical report describes the fractured hexagonal part of an implant abutment. The initial clinical sign was a loose abutment screw. Upon further clinical evaluation, the abutment was seen to have fractured and had wedged inside the implant body. Because the implant was a bone-level internal conical connection system, access and visibility were limited. A simple and economical technique with modified round-tip scissors was used to retrieve the fractured titanium abutment.

Fracture resistance of lithium disilicate restorations after endodontic access preparation: An in vitro study.

STATEMENT OF PROBLEM: Endodontic access preparation through a lithium disilicate restoration is a frequently encountered clinical situation. The common practice of repairing the accessed crown with composite resin may result in a weakened restoration. PURPOSE: The purpose of this in vitro study was to determine the effect of endodontic access preparation on the fracture resistance and microstructural integrity of monolithic pressed and monolithic milled lithium disilicate complete coverage restorations. MATERIAL AND METHODS: Twenty monolithic pressed (IPS e.max Press) and 20 monolithic milled (IPS e.max CAD) lithium disilicate restorations were fabricated. Ten of the pressed and 10 of the milled crowns were accessed for a simulated endodontic treatment and subsequently repaired by using a porcelain repair system and composite resin. All specimens were submitted to cyclic loading and then loaded to failure. Force data were recorded and analyzed with 2-way ANOVA followed by a post hoc test (Sidak correction) to indicate significant differences among the groups (α=.05). A Weibull analysis was also performed for each group. Eight (4 pressed and 4 milled) additional restorations were fabricated to complete a scanning electron microscope (SEM) analysis and evaluate the surface damage created by the endodontic access preparation. RESULTS: A statistically significant difference (P=.019) was found between the pressed intact and pressed repaired restorations and between the pressed intact and milled repaired restorations (P=.002). Specimens that were examined with an SEM showed edge chipping involving primarily the glaze layer around the access openings. CONCLUSIONS: Endodontic access preparation of lithium disilicate restorations resulted in a significantly reduced load to failure in the pressed specimens, but not in the milled specimens.

Effectiveness of silica-lasing method on the bond strength of composite resin repair to Ni-Cr alloy.

PURPOSE: The aim of this study was to evaluate the effectiveness of silica-lasing method for improving the composite resin repair of metal ceramic restorations. MATERIALS AND METHODS: Sixty Ni-Cr cylindrical specimens were fabricated. The bonding surface of all specimens was airborne-particle abraded using 50 µm aluminum oxide particles. Specimens were divided into six groups that received the following surface treatments: group 1-airborne-particle abrasion alone (AA); group 2-Nd:YAG laser irradiation (LA); group 3-silica coating (Si-CO); group 4-silica-lasing (metal surface was coated with slurry of opaque porcelain and irradiated by Nd:YAG laser) (Si-LA); group 5-silica-lasing plus etching with HF acid (Si-LA-HF); group 6-CoJet sand lased (CJ-LA). Composite resin was applied on metal surfaces. Specimens were thermocycled and tested in shear mode in a universal testing machine. The shear bond strength values were analyzed using ANOVA and Tukey's tests (α = 0.05). The mode of failure was determined, and two specimens in each group were examined by scanning electron microscopy and wavelength dispersive X-ray spectroscopy. RESULTS: Si-CO showed significantly higher shear bond strength in comparison to other groups (p < 0.001). The shear bond strength values of the LA group were significantly higher than those of the AA group (p < 0.05). No significant difference was found among lased groups (LA, Si-LA, Si-LA-HF, CJ-LA; p > 0.05). The failure mode was 100% adhesive for AA, Si-LA, Si-LA-HF, and CJ-LA. LA and Si-CO groups showed 37.5% and 87.5% cohesive failure, respectively. CONCLUSION: Silica coating of Ni-Cr alloy resulted in higher shear bond strength than those of other surface treatments.

Minimally Invasive Long-Term Management of Direct Restorations: the '5 Rs'.

The assessment and operative long-term management of direct restorations is a complex and controversial subject in conservative dentistry. Employing a minimally invasive (MI) approach helps preserve natural tooth structure and maintain endodontic health for as long as possible during the restorative cycle. This paper discusses how minimally invasive techniques may be applied practically to reviewing, resealing, refurbishing, repairing or replacing deteriorating/failed direct coronal restorations (the'5 Rs') and provides an update of contemporary MI clinical procedures. CPD/CLINICAL RELEVANCE: The assessment and long-term clinical management of deteriorating/failing direct restorations is a major component of the general dental practice workload and NHS UK budget expenditure for operative dentistry.

Management of a Dental Implant with Internal Thread Damage. A Patient Treatment Report.

When a patient presents with an implant with the internal threads damaged (or cross-threaded), a definitive restorative challenge may be faced. By having a difference in hardness between an abutment screw and the implant to which it is to be attached, there is potential for internal thread damage to the implant if the opposing threads do not interface properly. As such, the operator must use care when positioning the abutment and engaging the threads to prevent possible misalignment and damage to the internal aspect of the implant body. This article describes such a situation and the action taken to overcome the problem.

Replacement versus repair of defective restorations in adults: resin composite.

BACKGROUND: Composite filling materials have been increasingly used for the restoration of posterior teeth in recent years as a tooth-coloured alternative to amalgam. As with any filling material composites have a finite life-span. Traditionally, replacement was the ideal approach to treat defective composite restorations, however, repairing composites offers an alternative more conservative approach to the tooth structure where restorations are partly still serviceable. Repairing the restoration has the potential of taking less time and may sometimes be performed without the use of local anaesthesia hence it may be less distressing for a patient when compared with replacement. OBJECTIVES: To evaluate the effects of replacing (with resin composite) versus repair (with resin composite) in the management of defective resin composite dental restorations in permanent molar and premolar teeth. SEARCH METHODS: For the identification of studies relevant to this review we searched the Cochrane Oral Health Group's Trials Register (to 24 July 2013); the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2013, Issue 6); MEDLINE via OVID (1946 to 24 July 2013); EMBASE via OVID (1980 to 24 July 2013); BIOSIS via Web of Knowledge (1969 to 24 July 2013); Web of Science (1945 to 24 July 2013); and OpenGrey (to 24 July 2013). Researchers, experts and organisations known to be involved in this field were contacted in order to trace unpublished or ongoing studies. No restrictions were placed on the language or date of publication when searching the electronic databases. SELECTION CRITERIA: Trials were selected if they met the following criteria: randomised controlled trial (including split-mouth studies), involving replacement and repair of resin composite restorations in adults with a defective molar restoration in a permanent molar or premolar teeth. DATA COLLECTION AND ANALYSIS: Two review authors independently assessed titles and abstracts for each article identified by the searches in order to decide whether the article was likely to be relevant. Full papers were obtained for relevant articles and both review authors studied these. The Cochrane Collaboration statistical guidelines were to be followed for data synthesis. MAIN RESULTS: The search strategy retrieved 298 potentially eligible studies, after de-duplication. After examination of the titles and abstracts, full texts of potentially relevant studies were retrieved but none of the retrieved studies met the inclusion criteria of the review. AUTHORS' CONCLUSIONS: There are no published randomised controlled trials relevant to this review question. There is therefore a need for methodologically sound randomised controlled trials that are reported according to the Consolidated Standards of Reporting Trials (CONSORT) statement (www.consort-statement.org/). Further research also needs to explore qualitatively the views of patients on repairing versus replacement and investigate themes around pain, anxiety and distress, time and costs.

Microshear bond strength and finite element analysis of resin composite adhesion to press-on-metal ceramic for repair actions after various conditioning methods.

PURPOSE: This study evaluated the repair bond strength of differently surface-conditioned press-on-metal ceramic to repair composites and determined the location of the accumulated stresses by finite element analysis. MATERIALS AND METHODS: Press-on-metal ceramic disks (IPS InLine PoM, Ivoclar Vivadent) (N = 45, diameter: 3 mm, height: 2 mm) were randomly divided into 3 groups (n = 15 per group) and conditioned with one of the following methods: 9.5% hydrofluoric acid (HF) (Porcelain etch), tribochemical silica coating (TS) (CoJet), and an unconditioned group acted as the control (C). Each group was divided into three subgroups depending on the repair composite resins: a) Arabesk Top (V, a microhybrid; VOCO), b) Filtek Z250 (F, a hybrid;3M ESPE); c) Tetric EvoCeram (T, a nanohybrid; Ivoclar Vivadent) (n = 5 per subgroup). Repair composites disks (diameter: 1 mm, height: 1 mm) were photopolymerized on each ceramic block. Microshear bond strength (MSB) tests were performed (1 mm/min) and the obtained data were statistically analyzed using 2-way ANOVA and Tukey's post-hoc test (α = 0.05). Failure types were analyzed under SEM. Vickers indentation hardness, Young's modulus, and finite element analysis (FEA) were performed complementary to MSB tests to determine stress accumulation areas. RESULTS: MSB results were significantly affected by the surface conditioning methods (p = 0.0001), whereas the repair composite types did not show a significant effect (p = 0.108). The interaction terms between the repair composite and surface conditioning method were also statistically significant (p = 0.0001). The lowest MSB values (MPa ± SD) were obtained in the control group (V = 4 ± 0.8; F = 3.9 ± 0.7; T = 4.1 ± 0.7) (p < 0.05). While the group treated with T composite resulted in significantly lower MSB values for the HF group (T= 4.1 ± 0.8) compared to those of other composites (V = 8.1 ± 2.6; F = 7.6 ± 2.2) (p < 0.05), there were no significant differences when TS was used as a conditioning method (V = 5 ± 1.7; F = 4.7 ± 1; T = 6.2 ± 0.8) (p > 0.05). The control group presented exclusively adhesive failures. Cohesive failures in composite followed by mixed failure types were more common in HF and TS conditioned groups. Elasticity modulus of the composites were 22.9, 12.09, and 10.41 GPa for F, T, and V, respectively. Vickers hardness of the composites were 223, 232, and 375 HV for V, T, and F, respectively. Von Mises stresses in the FEA analysis for the V and T composites spread over a large area due to the low elastic modulus of the composite, whereas the F composite material accumulated more stresses at the bonded interface. CONCLUSION: Press-on-metal ceramic could best be repaired using tribochemical silica coating followed by silanization, regardless of the repair composite type in combination with their corresponding adhesive resins, providing that no cohesive ceramic failure was observed.

Improvements in dental care using a new mobile app with cloud services.

BACKGROUND/PURPOSE: Traditional dental care, which includes long-term oral hygiene maintenance and scheduled dental appointments, requires effective communication between dentists and patients. In this study, a new system was designed to provide a platform for direct communication between dentists and patients. METHODS: A new mobile app, Dental Calendar, combined with cloud services specific for dental care was created by a team constituted by dentists, computer scientists, and service scientists. This new system would remind patients about every scheduled appointment, and help them take pictures of their own oral cavity parts that require dental treatment and send them to dentists along with a symptom description. Dentists, by contrast, could confirm or change appointments easily and provide professional advice to their patients immediately. In this study, 26 dentists and 32 patients were evaluated by a questionnaire containing eight dental-service items before and after using this system. Paired sample t test was used for statistical analysis. RESULTS: After using the Dental Calendar combined with cloud services, dentists were able to improve appointment arrangements significantly, taking care of the patients with sudden worse prosthesis (p < 0.05). Patients also achieved significant improvement in appointment reminder systems, rearrangement of appointments in case of sudden worse prosthesis, and establishment of a direct relationship with dentists (p < 0.05). CONCLUSION: Our new mobile app, Dental Calendar, in combination with cloud services, provides efficient service to both dentists and patients, and helps establish a better relationship between them. It also helps dentists to arrange appointments for patients with sudden worsening of prosthesis function.