Tribochemical silicoating of amalgam promotes effective amalgam-resin repairs.

The purpose of this study was to determine the most effective method for bonding composite resin to artificially aged amalgam. A spherical amalgam alloy was triturated and condensed by hand into cylindrical plastic molds (6 mm in diameter and 4 mm in height) to create 90 specimens, which were then aged for 2 weeks in closed plastic containers at 23°C. The amalgam surfaces underwent 1 of 3 surface treatments (n = 30 per treatment): (1) air particle abrasion (APA) with 50-µm aluminum oxide particles applied with a force of 45 psi from a 10-mm distance, followed by rinsing with deionized water for 60 seconds; (2) APA following the same protocol with subsequent application of a metal primer (Alloy Primer); or (3) coating with 30-µm silica (CoJet) at a force of 45 psi from a 10-mm distance until the surface turned black. Specimens were then treated with 1 of 3 adhesives (n = 10 per adhesive per surface treatment): (1) 2-step total-etch adhesive (OptiBond Solo Plus), (2) 1-step self-etching adhesive (Scotchbond Universal), or (3) dual-cured resin cement (Panavia F 2.0). Each adhesive was applied to the treated amalgam surfaces following its manufacturer's instructions. The specimens were placed in a bonding clamp, and nanocomposite resin columns, 2.38 mm in diameter and 2.00 mm in height, were photocured (40 seconds, 500 mW/cm2) against the treated amalgam surfaces. The specimens were stored for 24 hours in 37°C deionized water and underwent shear bond strength testing at a crosshead speed of 0.5 mm/min. Data were analyzed using 2-way analysis of variance and post hoc analysis with the Tukey test at 95% confidence. The mean (SD) shear bond strength values ranged from 12.3 (1.2) MPa for aluminum oxide-treated surfaces bonded with OptiBond Solo Plus to 25.9 (4.6) MPa for silicoated surfaces bonded with Panavia F 2.0. All bonding agents produced the highest shear bond strength when the amalgam surface was silicoated. These results indicate that composite can be effectively bonded to amalgam via silicoating.

Fixed Partial Denture Designed by Combining the Whole 3D Digital Surface Morphology of the Provisional Restoration and Abutment Teeth Surfaces.

We introduce a new digital workflow to fabricate a fixed partial denture (FPD) utilizing the three-dimensional surface morphology of provisional restoration (PR) and abutment teeth. Scanned images of the full maxilla with abutment teeth, full maxilla with PR, and PR alone were superimposed. The surfaces of the final FPD were designed based on the entire morphology of the PR and abutment teeth surfaces. The inner and outer surfaces converged at the margin lines of the abutment teeth. Fine modifications to the final FPD design were performed manually, and the final FPD was fabricated and successfully installed in the patient.

Bone Dimensional Change Following Immediate Implant Placement in Posterior Teeth with CBCT: A 6-Month Prospective Clinical Study.

This prospective clinical study aimed to evaluate the peri-implant hard tissue dimensional change at 6 months of immediate implant placement with bone graft materials in the posterior area using cone-beam computed tomography (CBCT). Twelve dental implants were placed concurrently following tooth extraction in the posterior area and filled with xenograft particles. The CBCT images were taken immediately after surgical procedures and then at 6 months follow-up. To evaluate the hard tissue changes, the vertical and horizontal bone thickness were analyzed and measured using ImageJ software. Paired t-test or Wilcoxon match-pair signed-rank test was done to analyze the changes of hard tissue values at the same level between immediately and 6 months following immediate implant placement. Independent t-test or Mann-Whitney U test was used to analyze the dimensional change in the vertical and horizontal direction in buccal and lingual aspects. The level of significance was set at p value = 0.05. All implants were successfully osseointegrated. At 6 months follow-up, the vertical bone change at the buccal aspect was -0.69 mm and at the lingual aspect -0.39 mm. For horizontal bone thickness, the bone dimensional changes at 0, 1, 5, and 9 mm levels from the implant platform were -0.62 mm, -0.70 mm, -0.24 mm, and -0.22 mm, respectively. A significant bone reduction was observed in all measurement levels during the 6 months after implant placement (p value < 0.05). It was noted that even with bone grafting, a decrease in bone thickness was seen following the immediate implant placement. Therefore, this technique can be an alternative method to place the implant in the posterior area.

Quality of Information Regarding Repair Restorations on Dentist Websites: Systematic Search and Analysis.

BACKGROUND: Repairing instead of replacing partially defective dental restorations represents a minimally invasive treatment concept, and repairs are associated with advantages over complete restoration replacement. To participate in the shared decision-making process when facing partially defective restorations, patients need to be aware of the indications, limitations, and advantages or disadvantages of repairs. Patients are increasingly using the internet to gain health information like this online. OBJECTIVE: We aimed to assess the quality of German-speaking dentist websites on repairs of partially defective restorations. METHODS: Three electronic search engines were used to identify German-speaking websites of dental practices mentioning repairs. Regarding information on repairs, websites were assessed for (1) technical and functional aspects, (2) comprehensiveness of information, and (3) generic quality and risk of bias. Domains 1 and 3 were scored using validated tools (LIDA and DISCERN). Comprehensiveness was assessed using a criterion checklist related to evidence, advantages and disadvantages, restorations and defects suitable for repairs, and information regarding technical implementation. Generalized linear modeling was used to assess the impact of practice-specific parameters (practice location, practice setting, dental society membership, and year of examination or license to practice dentistry) on the quality of information. An overall quality score was calculated by averaging the quality scores of all three domains and used as primary outcome parameter. Quality scores of all three domains were also assessed individually and used as secondary outcomes. RESULTS: Fifty websites were included. The median score of quality of information was 23.2% (interquartile range [IQR] 21.7%-26.2%). Technical and functional aspects (55.2% [IQR 51.7%-58.6%]) showed significantly higher quality than comprehensiveness of information (8.3% [IQR 8.3%-16.7%]) and generic quality and risk of bias (3.6% [IQR 0.0%-7.1%]; P<.001/Wilcoxon). Quality scores were not related to practice-specific parameters (P>.05/generalized linear modeling). CONCLUSIONS: The quality of German-speaking dentist websites on repairs was limited. Despite sufficient technical and functional quality, the provided information was neither comprehensive nor trustworthy. There is great need to improve the quality of information to fully and reliably inform patients, thereby allowing shared decision making.

Five year evaluation of the complications observed in porcelain fused to metal (PFM) crowns placed at a university hospital.

OBJECTIVE: To determine the frequency of complications in crowns cemented over a 5-year period in a tertiary care hospital and also to report the survival of these crowns. METHODS: The retrospective cross-sectional study was conducted at the Aga Khan University Hospital, Karachi, from March 2017 to March 2018 and comprised porcelain fused-to-metal crowns placed on the anterior or posterior teeth that were fabricated at the institutional laboratory and were placed in institutional dental clinics in the preceding 5 years. Porcelain-fused to-metal The crowns were clinically and radio-graphically evaluated in a duration of two months for presence/absence of complications. Factors associated with the failure of the crowns, their survival and the impact of covariates, like gender, flossing and bruxism, on the survival time were determined. Data was analysed using SPSS 22. RESULTS: There were 150 crowns related to 107 patients who had a mean age of 45.0±11.4 years. The most common complication observed was open proximal contacts 9(6%) followed by de-cementation 8(5.3%), porcelain chipping 9(6%) and abutment fracture 2(1.3%). The 5-year survival rate of the crowns was 127(84.7%). The mean follow-up time was 57.2±1.0 months. Overall, year-wise survival of PFM crowns for one year till five years was 147 (98%), 144 (96%), 135 (90%), 130 (86%) and 119 (79%) respectively. CONCLUSIONS: The porcelain-fused-to-metal crowns had a high 5-year survival rate. Open proximal contacts represented the most common complication.

Antibacterial Properties of Nanoparticles in Dental Restorative Materials. A Systematic Review and Meta-Analysis.

Background and Objectives: Nanotechnology has become a significant area of research focused mainly on increasing the antibacterial and mechanical properties of dental materials. The aim of the present systematic review and meta-analysis was to examine and quantitatively analyze the current evidence for the addition of different nanoparticles into dental restorative materials, to determine whether their incorporation increases the antibacterial/antimicrobial properties of the materials. Materials and Methods: A literature search was performed in the Pubmed, Scopus, and Embase databases, up to December 2018, following PRISMA (Preferred Reporting Items for Systematic Review and Meta-Analysis) guidelines for systematic reviews and meta-analyses. Results: A total of 624 papers were identified in the initial search. After screening the texts and applying inclusion criteria, only 11 of these were selected for quantitative analysis. The incorporation of nanoparticles led to a significant increase (p-value <0.01) in the antibacterial capacity of all the dental materials synthesized in comparison with control materials. Conclusions: The incorporation of nanoparticles into dental restorative materials was a favorable option; the antibacterial activity of nanoparticle-modified dental materials was significantly higher compared with the original unmodified materials, TiO2 nanoparticles providing the greatest benefits. However, the high heterogeneity among the articles reviewed points to the need for further research and the application of standardized research protocols.

Repair potential of a new glass hybrid restorative system.

BACKGROUND: Repair of a failed amalgam or composite resin (CR) restoration has been extremely studied and proposed as a routine clinical treatment option; however, repair potential of glass ionomer-based restorative materials was not studied sufficiently in the literature. AIM: The aim of this study is to evaluate the repair potential of a glass hybrid (GH) restorative repaired either by the same material (GH) or CR after different surface treatments using microtensile bond strength (µTBS) test. METHODS AND MATERIALS: One hundred and twenty bar-shaped (2 × 2 × 8 mm) GH blocks were prepared. After aging, the specimens were divided into two groups (n = 60) and five subgroups (n = 12). The specimens in Group I were repaired with the following protocols: (a) no treatment + GH, (b) diamond bur (B) + GH, (c) cavity conditioner + GH, (d) cavity conditioner + universal adhesive (A) + GH, (e) A + GH, and specimens in Group II were repaired with (a) no treatment + CR, (b) B + CR, (c) B + A + CR, (d) 40% phosphoric acid + A + CR, (e) A + CR. The specimens that were subjected to µTBS testing, scanning electron microscopy evaluations, and fracture modes were determined. Data were analyzed using Kruskal-Wallis and Mann-Whitney U tests (P = 0.05). RESULTS: Repair using CR resulted in higher bond strengths (P < 0.001). The lowest bond strength was obtained in Group Ie. The highest bond strength was obtained when GH was roughened in Group IIc. CONCLUSION: Repair of restorative GH with CR appears as a preferred option to improve the bond strength.

SDR® vs traditional composite in class II restorations in primary molars.

This study aims to compare the clinical characteristics of a new flowable resin-based composite with those of a traditional composite when applied to deciduous molars for class II restorations. Twentyeight children between 6-12 years of age, with paired minimal Class II cavities present on their primary molars, were chosen. The paired cavities were restored with either a microhybrid composite or a new flowable resin-based composite. The composites were assigned to cavities in either the right or left side of the mouth, using random allocation tables. Each pair of restorations were clinically assessed at sixmonth intervals following the United States Public Health Service criteria. The prevalence of carious lesions was higher in maxillar molars (53.6%) compared to the mandibular molars (46.4%). At 24 months, Charlie or Delta scores in the paired groups were not seen in any patient, thus demonstrating a clinical success. The statistical analysis using Pearson’s chi-squared test did not reveal significant p-values for any parameter except the proximal contact showing significant p-values for this parameter. SDR appears to be the material of choice for the restoration of deciduous teeth due to its clinical features shown at 24 months as well as its ease and speed of application.

Deep infiltration for the treatment of hypomineralized enamel lesions in a patient with molar incisor hypomineralization: a clinical case.

This case report presents the technique of deep infiltration for the treatment of hypomineralized enamel lesions in a patient affected by molar incisor hypomineralization (MIH) with the purpose of obtaining an aesthetic improvement in the affected vestibular enamel. Deep infiltration treatment involves a sequence of steps starting with an initial mechanical abrasion of the outside surface of the enamel, followed by a phase of chemical erosion using 15% hydrochloric acid, penetration through the porosity of the enamel by a very fluid resin, and finally the repair of the thin layer of lost enamel using a composite. The aesthetic improvement of the elements affected by hypomineralized lesions is discernible immediately following treatment and becomes more accentuated with time. At the expense of minimal damage to surface enamel, deep infiltration enables treatment of all types of white spot enamel lesions, regardless of aetiology, offering the possibility of restoring an aesthetically pleasing smile for patients.

Analysis of flexural strength and contact pressure after simulated chairside adjustment of pressed lithium disilicate glass-ceramic.

STATEMENT OF PROBLEM: Research evaluating load-to-failure of pressed lithium disilicate glass-ceramic (LDGC) with a clinically validated test after adjustment and repair procedures is scarce. PURPOSE: The purpose of this in vitro study was to investigate the effect of the simulated chairside adjustment of the intaglio surface of monolithic pressed LDGC and procedures intended to repair damage. MATERIAL AND METHODS: A total of 423 IPS e.max Press (Ivoclar Vivadent AG) disks (15 mm diameter, 1 mm height) were used in the study. The material was tested by using an equibiaxial loading arrangement (n≥30/group) and a contact pressure test (n≥20/group). Specimens were assigned to 1 of 14 groups. One-half was assigned to the equibiaxial load test and the other half underwent contact pressure testing. Testing was performed in 2 parts, before glazing and after glazing. Before-glazing specimens were devested and entered in the test protocol, while after-glazing specimens were devested and glazed before entering the test protocol. Equibiaxial flexure test specimens were placed on a ring-on-ring apparatus and loaded until failure. Contact pressure specimens were cemented to epoxy resin blocks with a resin cement and loaded with a 50-mm diameter hemisphere until failure. Tests were performed on a universal testing machine with a crosshead speed of 0.5 mm/min. Weibull statistics and likelihood ratio contour plots determined intergroup differences (95% confidence bounds). RESULTS: Before glazing, the equibiaxial flexural strength test and the Weibull and likelihood ratio contour plots demonstrated a significantly higher failure strength for 1EC (188 MPa) than that of the damaged and/or repaired groups. Glazing following diamond-adjustment (1EGG) was the most beneficial post-damage procedure (176 MPa). Regarding the contact pressure test, the Weibull and likelihood ratio contour plots revealed no significant difference between the 1PC (98 MPa) and 1PGG (98 MPa) groups. Diamond-adjustment, without glazing (1EG and 1PG), resulted in the next-to-lowest equibiaxial flexure strength and the lowest contact pressure. After glazing, the strength of all the groups, when subjected to glazing following devesting, increased in comparison with corresponding groups in the before-glazing part of the study. CONCLUSIONS: A glazing treatment improved the mechanical properties of diamond-adjusted IPS e.max Press disks when evaluated by equibiaxial flexure and contact pressure tests.

[Retrospective study of dental treatment under general anesthesia of 62 disabled children and adolescents].

OBJECTIVE: To retrospectively figure out the oral health status, treatment and follow-ups after dental treatment under general anesthesia (DGA) of disabled children or adolescents. METHODS: Clinical data of disabled children or adolescents and normal children as control received DGA in the Department of Pediatric Dentistry, Peking University School and Hospital of Stomatology from August 2008 to September 2015 were recorded, including: gender, birth date, treatment date, disability type, oral health status before treatment, treatment content and follow-ups (in 1 year). Differences among ages and disabilities were analyzed statistically. RESULTS: Sixty-two disabled patients and fifty-seven controls were recruited, mean aged (9.38±5.22) years and (3.00±1.41) years. Most patients had 10 to 15 problem teeth with which the mean number of the disabled children and adolescents was (11.79±4.98) while that of the normal controls was (12.40±4.11). Caries, pulpitis, periapical periodontitis, dental trauma and developmental tooth anomalies of the disabled patients accounted for 67.56%, 13.54%, 15.15%, 1.07%, and 2.68%, respectively and the DMFT/dmft index was 11.55±5.56 while in the control group those were at 65.35%,19.09%,14.14%,0,1.41% and 12.23±4.42. The DMFT/dmft index of the disabled patients in the group 6-12 years (8.35±4.69) was significantly less than that of the other three groups (P<0.01) while no differences were found in disabilities (P=0.239). Resin restoration, pit and fissure sealant, preventive resin restoration, pulpotomy, pulpectomy/RCT, extraction and crown of the disabled patients were performed as 52.71%, 7.24%, 8.56%, 0.72%, 17.13%, 10.01% and 3.62% respectively whereas those made up as 56.31%, 1.27%, 0.13%, 2.29%, 19.87%, 7.90% and 12.23% in the control group. Thirty-five (56.45%) disabled patients and forty-three (75.44%) controls recalled. Problem teeth within one year after operation in diabled patients and controls were both nearly twice as much as the number within half a year. Restoration loss/fractured mainly occurred in anterior primary teeth while secondary/ recurrent caries and pulpitis/perapical periodontitis mostly occurred in primary molars. CONCLUSION: Oral health status in our disabled children and adolescents is poor. Though dental treatment under GA is an effective way to improve the oral health of disabled children and adolescents, periodic follow-ups and family oral health care are equal important for oral health maintenance.

Shear Bond Strength of Repair Systems to New CAD/CAM Restorative Materials.

PURPOSE: To evaluate the bond strength of repair systems (Ceramic Repair, Clearfil Repair) to computer-aided design/computer-assisted machining (CAD/CAM) restorative materials (IPS e.max CAD, Vita Suprinity, Vita Enamic, Lava Ultimate). MATERIALS AND METHODS: Thermally aged CAD/CAM restorative material specimens (5000 cycles between 5°C and 55°C) were randomly divided into two groups according to the repair system: Ceramic Repair (37% phosphoric acid + Monobond-S + Heliobond + Tetric N Ceram) or Clearfil Repair (40% phosphoric acid + mixture of Clearfil Porcelain Bond Activator and Clearfil SE Bond Primer + Clearfil SE Bond + Filtek Z250). The resin composite was light-cured on conditioned specimens. All specimens were stored in distilled water at 37°C for 24 hours and then additionally aged for 5000 thermal cycles. The shear bond strength test was performed using a universal testing machine (0.5 mm/min). Two-way ANOVA was used to detect significance differences according to the CAD/CAM material and composite repair system factors. Subgroup analyses were conducted using the least significant difference post-hoc test. RESULTS: The results of two-way ANOVA indicated that bond strength values varied according to the restorative materials (p < 0.05). No significant differences were observed between the CAD/CAM restorative materials (p > 0.05), except in the Vita Suprinity group (p < 0.05). Moreover, no differences were observed between the repair systems. CONCLUSIONS: Both the Clearfil and Ceramic repair systems used in the study allow for successful repairs.

Prosthetic Rehabilitation using a Telescopic Crown constructed with Computer-assisted Design and Computer-assisted Manufacturing: A Case Report with a 2-year Follow-up.

Aim and background: This case report describes a 74-year-old female patient whose teeth were rehabilitated using telescopic crowns (TCs) on abutments and fixed dental prostheses (FDPs) in the maxillary arch with the aid of computer-assisted design and computer-assisted manufacturing (CAD/CAM) technology. The mandibular arch was restored using casted removable dental prostheses (RDPs) and surveyed crowns. Case report: The treatment sequences were followed as recommended in the dental literature. First, existing defective restorations were eliminated, caries was removed, and excellent mouth preparation was performed. Subsequently, root canal treatments and post and core placements were conducted. The casts were mounted, and a new vertical dimension was established. Maxillary telescopic FDP and mandibular prostheses were fabricated. Finally, a regular and proper follow-up and maintenance program was implemented. Conclusion: The patient was satisfied with the esthetics and function of the telescopic FDP in the presence of the established occlusion. Clinical significance: The secondary coping of the telescopic FDP is cemented with temporary cement, which can be changed easily whenever it is loose. Furthermore, it is completely opposed to RDP in the mandibular posterior masticatory area. The prognoses will be good improvement; the patient was medically fit, motivated, and followed continual oral hygiene protocol. Keywords: Computer-assisted design, Computer-assisted manufacturing, Esthetic, Maxilla, Telescopic crown.

Clinical assessment of mineral trioxide aggregate in the treatment of deep carious lesions.

OBJECTIVE: This clinical study aimed to assess the effectiveness of mineral trioxide aggregate (MTA) and calcium hydroxide (Ca[OH]2) in the treatment of deep carious lesions using the direct complete caries excavation technique. SUBJECTS AND METHODS: Hundred permanent molars/premolars were capped either with Ca (OH)2 (n = 49) or MTA (n = 51) and restored with composite resin in 73 patients. Periapical radiographs were taken prior to the treatment, at 6 months and 12 months. Two calibrated examiners clinically and radiographically assessed the periapical pathology and pulpal symptoms. Inter-group comparisons of the observed values were analyzed using Fisher's exact test. Significance was predetermined at α = 0.05. RESULTS: Recall rates were 100% at 6 and 12 months. Four teeth capped with Ca(OH)2 (two each at the end of 6 and 12 months) and one tooth capped with MTA (at the end of 12 months) received endodontic emergency treatment because of symptoms of irreversible pulpitis that were clinically and/or radiographically established. There was no significant difference between the protection of the tooth vitality and pulp capping agents at 6 and 12 months (P = 0.238, P = 0.606, respectively). CONCLUSION: Both materials were clinically applicable at the end of 12 months.

Repair Versus Replacement of Restorations.

Dentists evaluate previously placed restorations every day to determine their acceptability. Many restorations have some defects associated with them. This article will review criteria useful to determine whether a restoration can be repaired, refurbished, or replaced. Methods and materials usefulfor repair will be discussed, as well as the science behind the decision-making.

Synthesis and molecular characterization of acrylate liquid crystalline resin monomers (ALCRM).

A novel biocompatible resin monomer 4—3—(acryloyloxy)—2—hydroxypropoxy) phenyl 4—(3—(acryloyloxy)—2—hydroxypropoxy) benzoate, as an oral restorative — acrylate liquid crystalline resin monomer (ALCRM) was synthesized. The intermediate product and the final product were characterized by differential scanning calorimetry (DSC), polarized optical microscope (POM), and nuclear magnetic resonance (NMR). A resin matrix which has a potential application in dental composites was prepared by photopolymerizing ALCRM and triethylene glycol dimethacrylate (TEGDMA) as a primary and diluted monomer with a photosensitizer of camphorquinone (CQ) and 2—(Dimethylamino)ethyl methacrylate (DMAEMA) mixture. The molar ratio of ALCRM and TEGDMA was 7:3. The properties such as the curing depth, curing time, and the volumetric shrinkage of the resin matrix were investigated and compared with a traditional composite resin matrix Bis—GMA. After photocuring polymerization, the conversion degree of the resin matrix is 68.06%, higher than Bis—GMA/TEGDMA; the curing time is 4.08±0.20min, the curing depth is 2.10±0.17mm, and the volumetric shrinkage is 3.62%±0.26%. All the properties exhibit a better performance of the prepared resin matrix than Bis—GMA.

Influence of repair procedure on composite-to-composite microtensile bond strength.

PURPOSE: To investigate the effect of different repair procedures and storage time on microtensile bond strength (µTBS) of a resin composite to an older one from a simulated previous restoration. METHODS: Composite disks were made by layering 2 mm-thick increments of a nanohybrid composite (Grandio) shade A1 in a Teflon mold (4 x 8 mm). Afterwards, they were light-cured and stored (37 degrees C/7 days) in a saline solution. Specimens were randomly divided into groups according to the surface treatment applied: (1) Composite surface was roughened with a bur (Cimara) and Solobond Plus adhesive was applied; (2) Sandblasting with 27 µm aluminum oxide particles (KaVo Rondoflex), and adhesive application; (3) Air-abrasion with 30 µm alumina particles coated with silica (CoJet Sand), silane (Monobond-S) and adhesive application; (4) Negative control group with only adhesive application. Afterwards, Grandio composite (shade A3.5) was packed incrementally on the treated surface obtaining another disk (4 x 8 mm). Repaired blocks were stored (24 hours or 6 months) and afterwards µTBS test was performed and failure mode was evaluated. Also, beams obtained from 8 mm-high composite blocks without any surface treatment were immediately submitted to µTBS test to determine Grandio composite cohesive bond strength (positive control group). Data were analyzed using ANOVA and Tukey's test (P < 0.05). RESULTS: The repair procedure affected µTBS values (P < 0.001) while neither storage time nor interactions did (P > 0.05). All repair procedures achieved bond strength values higher than the negative control group but they did not reach the composite's cohesive bond strength. The overall conclusion was that an increased superficial roughness by means of a bur, silica coating or alumina sandblasting improved µTBS of the repaired composite and bond strength remained stable after 6 months.

Using a porcelain furnace to debond cement-retained implant crown from the abutment after screw fracture: a clinical report.

When a screw fracture occurs on a cement-retained, implant-supported restoration, the abutment and restoration are completely separated from the implant's internal connection. Traditionally, an access hole is drilled through the crown to retrieve the broken screw, and the restoration can be placed again as a screw-retained restoration. This clinical report documents a patient whose broken abutment screw was retrieved from the restoration by burning off the cement and separating from the abutment without drilling an access hole.

Bond strength of repaired amalgam restorations.

This in vitro study investigated the interfacial flexural strength (FS) of amalgam repairs and the optimal combination of repair materials and mechanical retention required for a consistent and durable repair bond. Amalgam bricks were created, each with 1 end roughened to expose a fresh surface before repair. Four groups followed separate repair protocols: group 1, bonding agent with amalgam; group 2, bonding agent with composite resin; group 3, mechanical retention (slot) with amalgam; and group 4, slot with bonding agent and amalgam. Repaired specimens were stored in artificial saliva for 1, 10, 30, 120, or 360 days before being loaded to failure in a 3-point bending test. Statistical analysis showed significant changes in median FS over time in groups 2 and 4. The effect of the repair method on the FS values after each storage period was significant for most groups except the 30-day storage groups. Amalgam-amalgam repair with adequate condensation yielded the most consistent and durable bond. An amalgam bonding agent could be beneficial when firm condensation on the repair surface cannot be achieved or when tooth structure is involved. Composite resin can be a viable option for amalgam repair in an esthetically demanding region, but proper mechanical modification of the amalgam surface and selection of the proper bonding system are essential.

Matrixing for MID success.

The proper use of matrices can lead to successful, stable dental restorations. Their importance is further advanced in MID restorations. The 3 Cs of contour, contact, and control properly exercised with correct placement of matrices can enhance the long-term success of any restoration. Matrices create healthy gingival contours, mimic natural tooth contours, and also create good healthy contacts. All of these benefits can be achieved while controlling the flow of bonding products from the gums and keeping sulcular fluids from contaminating the bonding surfaces.