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.

Description and Durability of the Various Indirect Restoration Techniques in Molar-Incisor Hypomineralisation: A Systematic Review.

Molar-incisor hypomineralisation (MIH) is a qualitative defect of the enamel structure. Indirect restorations may represent the most suitable therapeutic solutions for patients presenting MIH with tooth restorative procedures. This systematic review aims to determine the feasibility of indirect restorations. MATERIALS AND METHODS: A systematic review has been performed and is reported following the PRISMA guidelines. It was performed on three databases (PubMed, Science Direct, and Google Scholar). Ten articles were included. RESULTS: Only two articles reported the use of CAD/CAM technologies, whereas the other eight preferred conventional registration and handmade stratification for ceramics. All indirect bonded restorations made of composite resins or ceramics had significant success rates. A temporary material was placed in most of the articles. There was no clear consensus for tissue conditioning before bonding. Depending on the authors and the articles, the follow-up period extended from 2 months to 6 years. CONCLUSIONS: The survival rate and the non-invasive procedures of indirect restorations are two main arguments that can help dental practitioners in daily practice. Development of CAD/ CAM technologies adds new perspectives in the registration, the design and production. However, more clinical trials are needed to confirm the conclusions.

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.

Dental attendance, restoration and extractions in adults with intellectual disabilities compared with the general population: a record linkage study.

BACKGROUND: Oral health may be poorer in adults with intellectual disabilities (IDs) who rely on carer support and medications with increased dental risks. METHODS: Record linkage study of dental outcomes, and associations with anticholinergic (e.g. antipsychotics) and sugar-containing liquid medication, in adults with IDs compared with age-sex-neighbourhood deprivation-matched general population controls. RESULTS: A total of 2933/4305 (68.1%) with IDs and 7761/12 915 (60.1%) without IDs attended dental care: odds ratio (OR) = 1.42 [1.32, 1.53]; 1359 (31.6%) with IDs versus 5233 (40.5%) without IDs had restorations: OR = 0.68 [0.63, 0.73]; and 567 (13.2%) with IDs versus 2048 (15.9%) without IDs had dental extractions: OR = 0.80 [0.73, 0.89]. Group differences for attendance were greatest in younger ages, and restoration/extractions differences were greatest in older ages. Adults with IDs were more likely prescribed with anticholinergics (2493 (57.9%) vs. 6235 (48.3%): OR = 1.49 [1.39, 1.59]) and sugar-containing liquids (1641 (38.1%) vs. 2315 (17.9%): OR = 2.89 [2.67, 3.12]). CONCLUSION: Carers support dental appointments, but dentists may be less likely to restore teeth, possibly extracting multiple teeth at individual appointments instead.

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.

Association of dietary habits with restorative dental treatment need and BMI among Finnish conscripts: a cross-sectional epidemiological study.

OBJECTIVE: Processed foods and fatty, sugary snacking products, such as fizzy drinks and desserts, have become more popular, causing a desire to replace meals with snacks worldwide. High-sugar and fat-rich food components have been reported to be associated with increased level of dental caries as well as underweight and overweight. The aim of the present cross-sectional population-based study was to analyse the eating behaviours of young, healthy Finnish males in association with oral health and BMI, considering self-reported and residential background factors. DESIGN: Cross-sectional study. SETTING: Finnish Defence Forces, Finland. PARTICIPANTS: The used clinical data were gathered from 13 564 Finnish conscripts born in the beginning of the 1990s through clinical check-ups. In addition, about 8700 of the conscripts answered a computer-assisted questionnaire ('Oral Health of the Conscripts 2011' data) about their background information and health habits. RESULTS: There was distinct variation in dietary patterns. Eating breakfast, regular physical exercise and daily tooth brushing all decreased the odds for restorative dental treatment need (decayed teeth), whereas smoking and drinking fizzy drinks for quenching thirst increased it. Eating breakfast and dinner were each associated with lower BMI, but smoking increased the odds for higher BMI (≥25 kg/m2). CONCLUSIONS: Regular, proper meals and especially eating breakfast decreased the odds for both dental caries and high BMI (≥25 kg/m2).

Oral health-related impact profile in full-mouth restored patients with two different tooth-colored restoration materials.

OBJECTIVES: To analyze the change of oral health impact profile (OHIP) in patients with full-mouth rehabilitations due to moderate/severe tooth wear dependent on different restorative materials (ceramic/experimental CAD/CAM composite). MATERIALS AND METHODS: Twenty-nine healthy patients (15 male/14 female, age 44.6 ± 28.4 years) requiring full-mouth rehabilitation due to different degrees of tooth wear were instructed to fill the German version OHIP-G49 questionnaire before (baseline) and 30 days after prosthetic treatment with ceramic (n = 17) or experimental CAD/CAM composite (n = 12) restorations. Questions were divided into five dimensions: appearance, oral functions, psychosocial impact, linguistic limitations, and orofacial pain; changes between both OHIP-questionnaires for each question and patient were dissected by difference values, separately. Data were analyzed with the Kolmogorov-Smirnov, Wilcoxon's signed-rank, Kruskal-Wallis, Mann-Whitney, and Cronbach's alpha tests (significance level p = 0.01). RESULTS: The appearance dimension showed the highest results (p < 0.001, 100% improvement with all values > 0); the linguistic limitations dimension presented the lowest improvement (p < 0.001). The other three dimensions were not statistically different. No statistical differences between the two materials depending on OHIP questionnaire results occurred. CONCLUSIONS: The esthetic appearance of the patients was influenced positively by full-mouth rehabilitation, irrespective of the material used. Improvements were also made in the parameters "toothache" and "problem of food intake." No statements could be made for the parameter "language." CLINICAL RELEVANCE: With an increasing number of patients with moderate/severe tooth wear, thorough knowledge about the improvement of OHIP is important. This information is advantageous for the consultation and handling of patients when complex treatments are planned.

Presentation of gaps around endodontic access cavity restoration by phase contrast-enhanced micro-CT.

OBJECTIVE: To evaluate the feasibility of synchrotron-based phase-contrast (PC) µCT for visualization of the gaps and differentiation between the gaps, restorative, and endodontic materials at the tooth-restoration interface. MATERIALS AND METHODS: Standardized access cavities were prepared in human maxillary molars and subjected to materials, simulating endodontic treatment: (1) saline irrigation; (2) NaOCl and 17% EDTA irrigation; (3) same as group 2, followed by application of Ca(OH)2; and (4) same as group 2, followed by application of root canal sealer. The access cavities were cleaned and restored using an etch-and-rinse adhesive and a composite material in multilayering technique. The samples were thermocycled (1000 cycles, 5-55 °C). Synchrotron-based µCT imaging was performed obtaining absorption and PC µCT images before and after the immersion of the samples into 50% AgNO3. PC µCT images were compared to absorption µCT and conventional optical microscopy images. RESULTS: PC µCT of unstained samples enabled the best visualization of gaps and differentiation of restorative and endodontic materials, contaminating the cavity surface. PC µCT revealed that AgNO3 staining leads to an overestimation of gap size due to anterograde and retrograde AgNO3 infiltration into dentinal tubules and underestimation of large gaps due to lack of AgNO3 penetration. CONCLUSION: Synchrotron PC µCT imaging enables better visualization of gap and differentiation of materials at the tooth-restoration interface. µCT imaging with AgNO3 staining has shown certain over- and underestimations. Future research should be aimed at incorporating PC µCT imaging of unstained samples for the validation of results obtained with other methods. CLINICAL SIGNIFICANCE: Contamination of cavity walls with an endodontic sealer or Ca(OH)2 leads to increased gap formation at the tooth-restoration interface.

[Features of dental rehabilitation of elderly patients after treatment of maxillofacial neoplasm.]

The purpose of this study is a comparative analysis of the effectiveness of the use of dental trays-transformers for the manufacture of prosthetic designs for elderly patients with acquired microstomia. Was conducted a clinical study of 12 hemimaxillectomy patients from 60 to 72 years. The 1st group included 6 patients with acquired microstomia, impressions of the jaws were obtained with dental trays-transformers. The 2nd group includes 6 patients who have less traumatic oral opening, they were removed with standard dental trays. The group of clinical control consisted of 6 patients with partial absence of maxillary teeth, who needed to prosthetic dentistry. The results of the study indicate the effectiveness of the use of trays-transformers to impressions of the jaw in elderly patients with restricted oral opening, as well as in patients with normal oral opening. Optimization of the stages of obturator prostheses allows to provide qualitative prosthetic care of patients with malignant neoplasms of the oropharyngeal region, which has a positive effect on the quality of life of elderly patients with acquired defects of the oropharyngeal region.

Changes in electromyography test results of patients with pathological abrasion of teeth. the role of anterior teeth in the process of rehabilitation.

OBJECTIVE: Introduction: Abrasion of teeth significantly affects electromyography results. Analyzing electromyograms of patients who needs complex rehabilitation, it is necessary to note absence of dissociation of the structure, appearance of spontaneous activity in one of the muscles, presence of the prevailing chewing side, appearance of low-amplitude oscillations in biocurrents. The aim: The purpose of this study was to determine the role of anterior teeth in the rehabilitation of patients with increased abrasion. PATIENTS AND METHODS: Material and methods: The experimental group involved patients (men and women) aged 20 to 59 years with increased abrasion of teeth I-III degrees. Patients were provided with all the necessary complexes of rehabilitation measures: direct restorations with composite materials using the adhesive system of the Vth generation (in case of light abrasion), indirect ceramic restorations (severe abrasion). All work was conducted in accordance with the Declaration of Helsinki (1964) and was approved by the Ethical Committee of the academy. RESULTS: Results: Activity of the right masseter muscle was slightly higher than that of the left one (313.42 ± 97.96 ms. against 226.69 ± 35.39 ms. respectively). At the same time the resting time of the left and right masseter muscles slightly differs (300.57 ± 30.93 ms. and 307.96 ± 49.47 ms. respectively). CONCLUSION: Conclusions: Rehabilitation of patients with increased abrasion using combined methods (direct composite restorations with the adhesive system of Vth generation and indirect ceramic restorations), give the possibility to restore the masticatory function (evidenced by an increase in the activity of right and leftmasseter muscle on 2%, a decrease in the rest phase on 20% almost and an increase in amplitude on 2.9%).

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.

[Effect of sandblasting on the microroughness of ceramic restorations]. / Vliianie aéroabrazivnoi obrabotki na mikrosherokhovatost' konstruktsii iz stomatologicheskoi polevoshpatnoi keramiki.

The influence of aero-abrasive technology on the microroughness of the ceramic samples standardized in shape, structure, and manufacturing method was studied by comparing the results obtained from the action of alumina particles of 27 and 50 µm size under a pressure of 0.5 and 2 atm for 5 seconds at a distance of 3 cm. To objectify the features of the treated surface relief its micro-roughness has been studied. With the help of a scanning electron microscope the morphology of studied samples was visualized. The data confirming the reliable absence of differences in the microroughness between the sandblasting methods under the given conditions was obtained. Microphotographs of samples surface obtained using the mode of reflected electrons detection showed no significant structural differences between all groups of samples. Thus, sandblasting can be integrated into the general algorithm as a stage of ceramics preparation for adhesive fixation since it does not cause mechanical damage to the surface, does not fundamentally change its structure and cleans the surface from contamination.

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.

The effect of abrading and cutting instruments on machinability of dental ceramics.

The aim was to investigate the effect of machining instruments on machinability of dental ceramics. Four dental ceramics, including two zirconia ceramics were machined by three types (SiC, diamond vitrified, and diamond sintered) of wheels with a hand-piece engine and two types (diamond and carbide) of burs with a high-speed air turbine. The machining conditions used were abrading speeds of 10,000 and 15,000 r.p.m. with abrading force of 100 gf for the hand-piece engine, and a pressure of 200 kPa and a cutting force of 80 gf for the air-turbine hand-piece. The machinability efficiency was evaluated by volume losses after machining the ceramics. A high-abrading speed had high-abrading efficiency (high-volume loss) compared to low-abrading speed in all abrading instruments used. The diamond vitrified wheels demonstrated higher volume loss for two zirconia ceramics than those of SiC and diamond sintered wheels. When the high-speed air-turbine instruments were used, the diamond points showed higher volume losses compared to the carbide burs for one ceramic and two zirconia ceramics with high-mechanical properties. The results of this study indicated that the machinability of dental ceramics depends on the mechanical and physical properties of dental ceramics and machining instruments. The abrading wheels show autogenous action of abrasive grains, in which ground abrasive grains drop out from the binder during abrasion, then the binder follow to wear out, subsequently new abrasive grains come out onto the instrument surface (autogenous action) and increase the grinding amount (volume loss) of grinding materials.

Quantitative percussion diagnostics as an indicator of the level of the structural pathology of teeth: Retrospective follow-up investigation of high-risk sites that remained pathological after restorative treatment.

STATEMENT OF PROBLEM: Structural damage may remain even after a tooth is restored. Conventional diagnostic aids do not quantify the severity of structural damage or allow the monitoring of structural changes after restoration. PURPOSE: The purpose of this retrospective clinical study was to provide an in-depth analysis of 9 high-risk sites after restoration. The analysis followed structural defects found upon disassembly, restorative materials used, therapeutic procedures provided, current longevity, and long-term quantitative percussion diagnostics (QPD) to monitor results. The hypothesis was that QPD can be used to quantify positive and negative changes in structural stability. MATERIAL AND METHODS: Sixty sites requiring restoration were part of an institutional review board-approved clinical study. Each participant was examined comprehensively, including QPD testing, at each follow-up. Long-term changes in normal fit error (NFE) values after restoration were evaluated according to a pathology rating system established in an earlier publication. Nine highly compromised sites were chosen for further analysis and monitored for an additional 6 years. RESULTS: Of the 9 high-risk sites (NFE>0.04), 7 sites improved and 2 sites deteriorated. Potential causes for each trend were documented. CONCLUSIONS: The data support the hypothesis that QPD can be used to monitor changes in structural stability after restoration. Knowledge of changes in advance of any symptoms allows further preventive or therapeutic intervention before serious structural damage can occur. Follow-up QPD indications of site improvement can also assure the clinician of the desired structural outcome.

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.