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Objective: To investigate the causes of bonding failures of orthodontic brackets and tubes and the effect of premedicating for saliva reduction., Materials and Methods: Premedication with atropine sulfate was administered randomly. Failure rate of brackets and tubes placed in a group of 158 consecutive patients was evaluated after a mean period of 67 weeks after bonding., Results: The failure rate in the group without atropine sulfate premedication was 2.4%. In the group with premedication, the failure rate was 2.7%. The Cox regression analysis of these groups showed that atropine application did not lead to a reduction in bond failures. Statistically significant differences in the hazard ratio were found for the bracket regions and for the dental assistants who prepared for the bonding procedure., Conclusions: Premedication did not lead to fewer bracket failures. The roles of the dental assistant and patient in preventing failures was relevant. A significantly higher failure rate for orthodontic appliances was found in the posterior regions.

Introduction: In this study, we aimed to evaluate the influence of clinical experience and the type of tooth (incisors, canines, and premolars) on the vertical accuracy of bracket placement with the Boone gauge., Methods: For this analysis, 4 groups were defined. Group 1 was composed of undergraduate students from the dental school with no previous experience in bonding orthodontic attachments; group 2 was composed of graduate students in the dental school; group 3 consisted of orthodontists with a maximum of 5 years of clinical experience; and group 4 comprised orthodontists with more than 5 years of clinical experience. Each group included 6 participants. A typodont was simulated with a Class I crowded malocclusion that reproduced the same occlusal characteristics for all groups to be bonded. All participants were instructed to bond 0.022 × 0.028-in edgewise brackets on the labial surfaces of the maxillary and mandibular incisors, canines, and premolars at a height of 4 mm from the incisal edge or the labial cusp tip. After each bonding procedure, all teeth were photographed after being removed from the typodont and positioned in a stabilizing device adapted to a camera stand., Results: The analyses of the variations showed that group 1 had the closest mean to 4 mm. However, this group also showed the greatest variance (0.433) (P <0.001). The smallest variations were observed in group 2 (variance, 0.093), followed by group 4 (variance, 0.094). The comparison of the means obtained in the groups of teeth at 4 mm demonstrated that the incisors showed a statistically significant difference (P <0.001), whereas canines (P = 0.133) and premolars (P = 0.913) did not., Conclusions: Operators are prone to fail in the placement of orthodontic attachments with the Boone gauge, despite their clinical experience in orthodontics. In the comparison of the groups of teeth, the incisors showed a statistically significant difference in relation to the height suggested for bracket placement with the Boone gauge., (Copyright © 2015 American Association of Orthodontists. Published by Elsevier Inc. All rights reserved.)

Purpose: Temporomandibular disorders are a group of symptoms related to the impaired function of the temporomandibular joints and associated muscles. Occlusal splint therapy is a common treatment in the aforementioned syndrome. One of the methods of manufacturing occlusal splints is to place a polymer on thermoplastic foil. The aim of this study was to evaluate the shear bond strength of light- and self-cured resins bonded to thermoplastic foil dependent on artificial aging., Materials and Methods: Thirty cylinders composed of light-cured resin and 30 cylinders made of self-cured resin were attached to 60 rectangular thermoplastic plates. All specimens were divided into six groups. A control study was conducted for groups 1 and 2. The other preparation groups were subjected to thermocycling by setting appropriately 1000 cycles for groups 3 and 4 and 3000 cycles for groups 5 and 6 in distilled water. Bond strength was measured in a universal testing machine. The results were subjected to statistical analysis using the Mann-Whitney U test (p ≤ 0.05)., Results: The statistics revealed that the values of the shear bond strength for specimens composed of self-cured resin after 1000 and 3000 thermocycles were significantly higher than on those made of light-cured resin (p = 0.003 and p = 0.002)., Conclusion: The shear bond strength between the self-cured resin and the thermoplastic foil was higher and more resistant to aging than the shear bond strength between the light-cured resin and the thermoplastic foil., (© 2014 by the American College of Prosthodontists.)

Aim: Several surveys evaluate different retention approaches among orthodontists, but none exist for general dentists. The primary aim of this survey was to record the preferred fixed retainer designs and retention protocols amongst general dentists and orthodontists in Switzerland. A secondary aim was to investigate whether retention patterns were associated with parameters such as gender, university of graduation, time in practice, and specialist status., Methods: An anonymized questionnaire was distributed to general dentists (n = 401) and orthodontists (n = 398) practicing in the German-speaking part of Switzerland. A total of 768 questionnaires could be delivered, 562 (73.2 %) were returned and evaluated. Descriptive statistics were performed and responses to questions of interest were converted to binary outcomes and analyzed using multiple logistic regression. Any associations between the answers and gender, university of graduation (Swiss or foreign), years in practice, and specialist status (orthodontist/general dentist) were assessed., Results: Almost all responding orthodontists (98.0 %) and nearly a third of general dentists (29.6 %) reported bonding fixed retainers regularly. The answers were not associated with the practitioner's gender. The university of graduation and number of years in practice had a moderate impact on the responses. The answers were mostly influenced by specialist status., Conclusion: Graduation school, years in practice, and specialist status influence retention protocol, and evidence-based guidelines for fixed retention should be issued to minimize these effects. Based on the observation that bonding and maintenance of retainers are also performed by general dentists, these guidelines should be taught in dental school and not during post-graduate training.

Objective: To measure and compare bracket transfer accuracy of five indirect bonding (IDB) techniques., Materials and Methods: Five IDB techniques were studied: double polyvinyl siloxane (double-PVS), double vacuum-form (double-VF), polyvinyl siloxane vacuum-form (PVS-VF), polyvinyl siloxane putty (PVS-putty), and single vacuum-form (single-VF). Brackets were bonded on 25 identical stone working models. IDB trays were fabricated over working models (n  =  5 per technique) to transfer brackets to another 25 identical stone patient models. The mesiodistal (M-D), occlusogingival (O-G), and faciolingual (F-L) positions of each bracket were measured on the working and patient models using digital photography (M-D, O-G) and calipers (F-L). Paired t-tests were used to compare bracket positions between working and patient models, and analysis of variance was used to compare bracket transfer accuracy among the five techniques., Results: Between the working and patient models, double-VF had the most teeth with significant differences (n  =  6) and PVS-VF the fewest (n  =  1; P < .05). With one exception, all significant differences were ≤0.26 mm and most (65%) were ≤0.13 mm. When the techniques were compared, bracket transfer accuracy was similar for double-PVS, PVS-putty, and PVS-VF, whereas double-VF and single-VF showed significantly less accuracy in the O-G direction., Conclusions: Although overall differences in bracket position were relatively small, silicone-based trays had consistently high accuracy in transferring brackets, whereas methods that exclusively used vacuum-formed trays were less consistent.

Purpose: While it has been shown that no method produces specimens with exactly the same cross-sectional bonded area (BA), BA variations within and between studies are a well-known covariate in microtensile test results. However, no method has yet been described to accurately account for its influence. A procedure is presented that allows controlling for variations of BA effects on results. Further, a proposal for reporting is presented which enables results of different studies to be compared., Materials and Methods: Partially using the results of the report in which the microtensile test was originally described, 144 both general (caused by differences in BA) and specific (due to a material's performance differences and intrinsic biological variability of specimens) variabilities were separated through linear regression of microtensile (MPa) to BA (mm2) pooled results. Comparing the specific variability of specimens - the residuals to the regression line - of groups allowed assessing differences between groups., Results: A means comparison of residuals showed that specific differences were significant (t-test, p = 0.0004). The null hypothesis could be rejected: materials' performances were different. This could not be determined in the original report, since BA variability was very high. A proposal for reporting of results to facilitate their clinical interpretation and comparison between studies is presented., Conclusion: Controlling for general variability caused by differences in BA size allows precise comparison of microtensile tests results.

Introduction: Current studies have compared indirect bonding with direct placement of orthodontic brackets; many of these have shown that indirect bonding is generally a more accurate technique. However, the reproducibility of an indirect bonding setup by an orthodontist has yet to be described in the literature. Using cone-beam computed tomography and computer-assisted modeling software, we evaluated the consistency of orthodontists in placing orthodontic brackets at different times., Methods: Five orthodontists with experience in indirect bonding were selected to place brackets on 10 different casts at 3 time periods (n = 30 per orthodontist). Each participant completed an initial indirect bonding setup on each cast; subsequent bracket placements were completed twice at monthly intervals for comparison with the initial setup. The casts were scanned using an iCAT cone-beam computed tomography scanner (Imaging Sciences International, Hatfield, Pa) and imported into Geomagic Studio software (Geomagic, Research Triangle Park, NC) for superimposition and analysis. The scans for each time period were superimposed on the initial setup in the imaging software, and differences between bracket positions were calculated. For each superimposition, the measurements recorded were the greatest discrepancies between individual brackets as well as the mean discrepancies and standard deviations between all brackets on each cast., Results: Single-factor and repeated-measure analysis of variance showed no statistically significant differences between time points of each orthodontist, or among the orthodontists for the parameters measured. The mean discrepancy was 0.1 mm for each 10-bracket indirect bonding setup., Conclusions: Orthodontists are consistent in selecting bracket positions for an indirect bonding setup at various time periods., (Copyright © 2013 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.)

Aim: The objective of the current epidemiologic study was to investigate characteristics associated with bracket failure in bonded brackets., Materials and Methods: A retrospective study on data of 144 patients treated during 2009 to 2012 was done. Baseline data including age, gender, malocclusion, bite type and debonding incidences per teeth were retrieved. ANOVA analysis and t-test were used to evaluate the data., Results: Second premolar teeth had significantly higher debonding incidences. Patients' age was negatively correlated with debonding incidences. No difference was observed for various types of malocclusion (class I, II and III), arch side (right or left) or arch location (upper or lower). However, deep bite patients had significantly higher failure incidents., Conclusion: For a total of 144 patients with 2,524 bonded brackets, the overall failure rate was 7.8%. Deep bite was the only factor that was associated with higher bracket failure. The bracket failure incidents tend to decrease as patients age increase., Clinical Significance: Deep bite patients and also second premolar teeth seem to be especially prone to debonding incidents. Care must be taken to avoid premature contacts in deep bite patients. Also strict adherence to moisture control protocols when bonding second premolar teeth is recommended since these teeth are at increased risk for debonding.

Purpose: To test the hypothesis that stress distribution is more complex than generally assumed during microtensile testing by determining the stress level in the adhesive region of a virtual dentin-adhesive-composite stick using FEA (finite element analysis)., Materials and Methods: A 3D FEA model simulating a dentin-adhesive-composite stick was analyzed. The length of the composite and the dentin was 5.0 mm each and the thickness of the adhesive layer was 0.02 mm. For the stress analysis, either only one lateral side of the stick or both end surfaces were attached. A 20-N load was then exerted on the stick with its 1.0 mm2 cross-sectional area, and von Mises stresses were calculated., Results: Large variations in stress levels existed. The highest stresses were located in the dentin and composite sections, near the adhesive interface. The stress level in these regions in the stick attached to one lateral side was more than 5 times higher than the 20 MPa stress calculated by dividing the force with the crosssectional area. For the specimen glued to the ends of the sticks, the stress level differences at the bonded interfaces were around 22 MPa, which decreased to 12 to 14 MPa in the center of the adhesive. Thus, this load condition yielded von Mises stress levels at the interface that were closer to the expected stress level than were the lateral-side attached specimens., Conclusion: The calculated stress levels were higher and more complex than the strength values obtained by dividing the load at failure by the cross-sectional area. Reported strength values from microtensile tests therefore do not represent the true bond strength values at either the dentin/adhesive or adhesive/composite interface. However, the high stress levels in dentin and composite may explain the cohesive failures reported in the literature.

Objectives: This study evaluated and compared Weibull parameters of resin bond strength values using six different general-purpose statistical software packages for two-parameter Weibull distribution., Methods: Two-hundred human teeth were randomly divided into 4 groups (n=50), prepared and bonded on dentin according to the manufacturers' instructions using the following resin cements: (i) Variolink (VAN, conventional resin cement), (ii) Panavia21 (PAN, conventional resin cement), (iii) RelyX Unicem (RXU, self-adhesive resin cement) and (iv) G-Cem (GCM, self-adhesive resin cement). Subsequently, all specimens were stored in water for 24h at 37°C. Shear bond strength was measured and the data were analyzed using Anderson-Darling goodness-of-fit (MINITAB 16) and two-parameter Weibull statistics with the following statistical software packages: Excel 2011, SPSS 19, MINITAB 16, R 2.12.1, SAS 9.1.3. and STATA 11.2 (p≤0.05). Additionally, the three-parameter Weibull was fitted using MNITAB 16., Results: Two-parameter Weibull calculated with MINITAB and STATA can be compared using an omnibus test and using 95% CI. In SAS only 95% CI were directly obtained from the output. R provided no estimates of 95% CI. In both SAS and R the global comparison of the characteristic bond strength among groups is provided by means of the Weibull regression. EXCEL and SPSS provided no default information about 95% CI and no significance test for the comparison of Weibull parameters among the groups. In summary, conventional resin cement VAN showed the highest Weibull modulus and characteristic bond strength., Significance: There are discrepancies in the Weibull statistics depending on the software package and the estimation method. The information content in the default output provided by the software packages differs to very high extent., (Copyright © 2012 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.)

Objectives: The aim of this study was to compare the fracture load of veneered anterior zirconia crowns using normal and Weibull distribution of complete and censored data., Methods: Standardized zirconia frameworks for maxillary canines were milled using a CAD/CAM system and randomly divided into 3 groups (N=90, n=30 per group). They were veneered with three veneering ceramics, namely GC Initial ZR, Vita VM9, IPS e.max Ceram using layering technique. The crowns were cemented with glass ionomer cement on metal abutments. The specimens were then loaded to fracture (1 mm/min) in a Universal Testing Machine. The data were analyzed using classical method (normal data distribution (μ, σ); Levene test and one-way ANOVA) and according to the Weibull statistics (s, m). In addition, fracture load results were analyzed depending on complete and censored failure types (only chipping vs. total fracture together with chipping)., Results: When computed with complete data, significantly higher mean fracture loads (N) were observed for GC Initial ZR (μ=978, σ=157; s=1043, m=7.2) and VITA VM9 (μ=1074, σ=179; s=1139; m=7.8) than that of IPS e.max Ceram (μ=798, σ=174; s=859, m=5.8) (p<0.05) by classical and Weibull statistics, respectively. When the data were censored for only total fracture, IPS e.max Ceram presented the lowest fracture load for chipping with both classical distribution (μ=790, σ=160) and Weibull statistics (s=836, m=6.5). When total fracture with chipping (classical distribution) was considered as failure, IPS e.max Ceram did not show significant fracture load for total fracture (μ=1054, σ=110) compared to other groups (GC Initial ZR: μ=1039, σ=152, VITA VM9: μ=1170, σ=166). According to Weibull distributed data, VITA VM9 showed significantly higher fracture load (s=1228, m=9.4) than those of other groups., Significance: Both classical distribution and Weibull statistics for complete data yielded similar outcomes. Censored data analysis of all ceramic systems based on failure types is essential and brings additional information regarding the susceptibility to chipping or total fracture., (Copyright © 2011 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.)

Purpose: Orthodontic treatment in the orthognathic surgical patient commonly involves banding or bonding of erupted molars. Appliance displacement during surgery is a potentially serious complication. However, limited data exist about the prevalence of banding or bonding and the frequency of appliance failure in this patient population. The purpose of this study was to determine the prevalence of banding and bonding and appliance failure in a large cohort of patients undergoing orthognathic surgery at a single institution., Patients and Methods: All patients who underwent orthognathic surgery from 2004 to 2006 at Kaiser Permanente Oakland Medical Center were identified, and preoperative and postoperative radiographs were retrospectively reviewed. Study variables included age at time of surgery, gender, date and type of surgery, Angle classification of occlusion, type of orthodontic appliance (band or bond) on erupted molar teeth, and failure as detected from postoperative imaging., Results: In the 1,003 patients there was a greater overall prevalence of molar bands (74.3%) than bonds (19.2%) with the vast majority (84.4%) of first molars and fewer (64.2%) second molars having banded appliances. The prevalence of bonded first and second molars was lowest in 2004 and highest in 2006. Appliance failure occurred in 19 patients (1.9%), most often involving maxillary second molars, and all were bonds. Of the 19 failed bonds, 2 were displaced into the mandibular osteotomy site and 1 was displaced into the posterior pharynx., Conclusion: The prevalence of bonded molars in surgical patients increased from 2004 to 2006. Appliance malfunction occurred most often in bonded maxillary second molars. Although rare, failure and displacement of bonded appliances may have significant consequences., (Copyright © 2011 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.)

Objective: The aim of this study was to retrospectively assess the frequency and type of lower bonded retainer failures and to analyze the possible influence of operator experience., Patients and Methods: The records of 1062 patients with lower bonded retainers were analyzed with respect to retainer type and failure, timing of failure and differences among operators., Results: 34.9% of all patients experienced retainer failure. Cuspid retainers with two bonding sites failed significantly less often than multiple teeth retainers with six bonding sites. One or more bonding sites became detached in 22.8% of the patients, 17.9% had at least one total retainer loss, while only 0.8% of the patients suffered from retainer fractures. Experienced orthodontists exhibited significantly fewer failures than postgraduate students., Conclusions: The present cohort presented a relatively high failure rate of 34.9%. Lower bonded cuspid retainers failed somewhat less often than 3-3 retainers. In addition less operator experience was likely to correlate with a higher failure rate.

Unlabelled: Statistical analysis interpretation is a critical field in scientific research. When there is more than one main variable being studied in a research, the effect of the interaction between those variables is fundamental on experiments discussion. However, some doubts can occur when the p-value of the interaction is greater than the significance level., Objective: To determine the most adequate interpretation for factorial experiments with p-values of the interaction nearly higher than the significance level., Materials and Methods: The p-values of the interactions found in two restorative dentistry experiments (0.053 and 0.068) were interpreted in two distinct ways: considering the interaction as not significant and as significant., Results: Different findings were observed between the two analyses, and studies results became more coherent when the significant interaction was used., Conclusion: The p-value of the interaction between main variables must be analyzed with caution because it can change the outcomes of research studies. Researchers are strongly advised to interpret carefully the results of their statistical analysis in order to discuss the findings of their experiments properly.

Objective: To investigate the use of fixed appliances in the UK., Design: Prospective postal questionnaire., Setting: UK., Participants: All members of the General Dental Council Specialist List in Orthodontics still in active practice and not in training posts., Method: A preemptive letter of explanation was sent inviting orthodontists to participate in the survey. The questionnaire was subsequently posted to 935 specialists. Data analysis investigated differences in clinical practice related to varying provider groups, level of operator experience and geographical region., Results: The response rate achieved was 66.3%. A majority of orthodontists routinely used the 0.022 inch pre-adjusted edgewise system, standard size Siamese pattern stainless steel brackets, conventionally ligated and bonded using standard etch and light cured composite. Nickel titanium and stainless steel were the most popular archwire materials. Anchorage was supported routinely by palatal and lingual arches in up to 25% and by headgear in over a third of respondents. Newer innovations showed variable popularity. Self-etching primer was used routinely by one-third of respondents with 11% use of self-ligating brackets. Banding of first molars was preferred by over 60% of clinicians. Bone screw implants were used by only 0.2% of respondents. Clinicians with less than 10 years experience used more headgear, light curing, MBT prescription and molar bonding. Operators with over 20 years experience used more chemically cured bonding, Roth prescription, banded first molars, 0.018 inch slot size and Tip-Edge(TM), with less use of headgear. Fixed appliance use differed from that reported in the US with lower use in the UK of standard edgewise and Roth systems, aesthetic, miniaturised and 0.018 inch slot brackets and rapid maxillary expansion., Conclusion: Most UK orthodontic specialists routinely used the 0.022 inch pre-adjusted edgewise system with standard size Siamese steel brackets bonded using standard etch and light cured composite with conventional ligation. Variations were seen between different provider groups, types of treatment funding, levels of operator seniority and geographical regions. Differences were noted particularly in the use of bracket prescription and design, types of molar attachment and anchorage control.

Purpose: To elucidate how dentists access knowledge sources when choosing adhesive agents for bonded restoration and whether these resources influenced the selection of materials., Materials and Methods: A national survey was carried out involving dentists in South Korea. The questionnaire included the status of the operator, clinical techniques, and materials. A total of 12,193 e-mails were distributed, 2632 were opened by recipients, and 840 responses were collected., Results: For primary information resources in material selection, 55.8% (n = 469) of the responders mentioned continuing education. This selection criteria varied according to the working status of the clinician (p < 0.0001). The choice of bonding system was influenced by of the length of the career (p < 0.0001), and the preferred bonding systems differed according to the source of the information (p = 0.035)., Conclusion: The popular bonding systems were not ranked according to the bonding strategy, but a preference was found for specific brands or manufacturers. To decrease the confusion of clinicians related to the selection of bonding materials, evidence-based guidelines need to be comprehensibly organized and efficiently approached in clinics.

The objective of this study was to survey retention procedures used in orthodontic practices in The Netherlands. A questionnaire was sent to all 279 orthodontists working in The Netherlands. The questionnaire consisted of six parts, mainly containing multiple-choice questions. Information as to background data on the individual orthodontist, retention in general, frequency of different types of removable or bonded retainers that were used, retention protocol, and the type and size of the wire used for bonded retainers was assessed. All statistical analyses were performed using Statistical Package for Social Sciences version 12.0.1. Tests for the relationship between two items were based on the chi-square test. The overall response rate was 91 per cent. Most orthodontists placed a bonded retainer in the upper and lower arch, except when the upper arch was expanded during treatment or when extractions were performed in the upper arch, in which case they placed a removable retainer. Opinions varied with regard to how many hours the removable retainers should be worn and the duration of the retention phase. Contraindications for bonded retainers were given by 96 per cent of the orthodontists, with poor oral hygiene being the most commonly mentioned. As far as bonded retainers were concerned, 84 per cent of the orthodontists preferred permanent retention. Fifty-nine per cent of the orthodontists believed that a practice guideline for retention after orthodontic treatment needs to be developed, which was confirmed by the varied responses in this survey.

In the past decade, follow-up studies on fiber-reinforced composite fixed partial dentures (FRC FPDs) have been described. Combining the results of these studies to draw conclusions about the effectiveness of FRC FPDs is challenging. The objective of this systematic review was to obtain survival rates of FRC FPDs and to explore the relationships between reported survival rates and risk factors. In a literature-selection procedure on the clinical performance of FRC FPDs, 15 studies, reporting on 13 sets of patients, were analyzed. The Kaplan-Meier estimate of the overall survival, based on the data from all sets of patients (n = 435) was 73.4% (69.4-77.4%) at 4.5 yr. Converted survival rates at 2 yr of follow-up showed substantial heterogeneity between studies. It was not possible to build a reliable regression model that indicated risk factors. The technical problems most commonly described were fracture of the FPD and delamination of the veneering composite.

Unlabelled: This investigation assessed the effectiveness of alternative treatments for the replacement of amalgam and resin-based composite restorations. Sixty-six patients (age 18 to 80 years, mean = 26.6) with 271 (amalgam [n = 193] and resin-based composite [n = 78]) defective restorations were randomly assigned to one of five different treatment groups: A) Repair (n = 27); B) Sealing of margins (n = 48); C) Refurbishing (n = 73); D) Replacement (n = 42) and E) Untreated (n = 81). USPHS/Ryge criteria were used to determine the quality of the restorations. Two calibrated examiners (Cohen's Kappa 0.74) assessed the restorations independently at the beginning of the study (baseline) and at two years after treatment using seven parameters from the USPHS/Ryge criteria (Marginal Adaptation, Anatomic Form, Roughness, Marginal Stain, Occlusal Contact, Secondary Caries and Luster)., Results: Two-hundred and fifty-six restorations (178 amalgam and 78 resin-based composite) were examined at the two-year recall exam. The sealing of marginal defects showed significant improvements in marginal adaptation (p < 0.05). Refurbishing of the defective restorations significantly improved anatomic form (p < 0.0001), luster (p < 0.016), marginal adaptation (p < 0.003) and roughness (p < 0.0001). The repair significantly improved anatomic form (p < 0.002) and marginal stain (p < 0.002). Replacement showed significant improvements for all parameters (p < 0.05). The Untreated group showed significant deterioration on marginal adaptation (p < 0.013)., Conclusions: The two-year recall examination showed that sealant, repair and refurbishing treatments improved the clinical properties of defective amalgam and resin-based composite restorations by increasing the longevity of the restorations with minimal intervention.

Objective: This paper utilises a Poisson frailty regression model with clustering to report on the failure rates of sealants placed and repaired during a three-year follow-up school-based comprehensive preventive programme., Basic Research Design: The programme included annual application/reapplication of light-cured fissure sealants in 210 12-year-old subjects over three years. Sealants placed at the commencement of each year of the programme were assessed for retention 12 months later and repair/reapplication was undertaken at that time for those surfaces judged to require it. An application of a Poisson regression model with random effects ("frailties") and clustering was used in this paper to allow for heterogeneity between subjects. Whilst it appears that the direct utilization of frailty models in determining fissure sealant failure rates has not been reported, it is clearly an appropriate use of this statistical method. A total of 1,544 sealants were placed during the study period. Of these, 1,038 (67.2%) were first placements at baseline and 506 (32.8%) were repairs/reapplications. Of these repairs/reapplications, 206 (40.7%) were performed at first year follow-up and 300 (59.3%) at second year follow-up., Results: The Failure Rate Ratios were statistically significantly greater for second molars cf. first molars (FRR=1.33, p=0.008) and for lower molars cf upper molars (FRR=1.32, p<0.001). Failure rate ratios for sealants placed in the distal occlusal pit and fissures cf. mesial occlusal pit and fissures were significantly higher (FRR=1.33, p<0.001). A significant interaction was found for molar type versus pit and fissure site (p=0.009). There was no significant interaction between molar type and arch., Conclusions: Sealants placed on second molars, those placed on lower molars and those placed on the distal fissure sites have a higher failure rate. As individual tooth sites in the mouth are not independent, any statistical analysis should allow for these associations when assessing sealant retention.

Purpose: To assess and discuss the true value and perceived relevance of present day dental adhesive tensile bond strength studies. There are flaws and inconsistencies present in the data due to the inherent variations in testing methods, conditions, and types of samples prepared. In particular, surface areas of specimens need to be standardized. This review considers the significant impact of different surface areas of tooth specimens utilized in testing., Results: On review of the data, relatively higher MPa values do not necessarily indicate improved dental adhesive products or procedures.

There has been a resurgence of interest in the indirect bonding technique for orthodontics. The procedure is not often used in the UK and the reasons for this, as well as the renewal of interest, are explored. A costing exercise suggests that the cost-effectiveness of the technique may be improved by the described Burton technique and, in the light of current manpower considerations, the implications for its use in the future are also discussed.

In 1995, a survey requesting information about the utilization of certain prosthodontic techniques was mailed to 3,544 graduates of a midwestern dental school. Responses were received from 1,455 alumni, representing a 41 percent return rate. In general, the results are consistent with international and national trends and show significant disparity in the utilization rates of certain procedures between general dentists and prosthodontists, as well as a disconnect between what is taught in the undergraduate dental educational program and what is applied in practice. For example, while prosthodontists typically apply what was taught in their educational program, utilization rates of general dentists for the facebow was 29.64 percent; the custom tray 68.48 percent; border molding 58.67 percent; altered casts 24.10 percent; custom posts 49.29 percent; prefabricated posts 67.54 percent; and semi-adjustable articulators 50.64 percent. While no solutions to this disconnect are offered the authors do pose important questions that must be addressed by the dental educational community.

Statement of Problem: With the development of new adhesive resin cements, the question of surface treatment of noble metal castings with primers has become an important issue., Purpose: This study compared the tensile bond strength and its durability of a new metal primer (Alloy Primer, Kuraray) to 2 noble metal alloys (Au-Ag-Cu-Pt and Au-Pt-Pd-Ag-In)., Material and Methods: Sixty cast disk specimens of each alloy were polished, grit blasted with 50 microm Al(2)O(3), and ultrasonically cleaned in 96% isopropanol. Then, they were either nonprimed or primed only with the Alloy Primer or Alloy Primer combined with ED Primer (Kuraray). Plexiglas tubes filled with self-curing composite resin (Clearfil FII, Kuraray) were bonded to the metal samples with the use of an alignment apparatus and a self-curing luting cement (Panavia 21 Ex). The samples were stored in water, either for 3 days with no thermal cycling or for 150 days with 37,500 thermal cycles. After the different storage conditions, the tensile bond strengths of the specimens were determined., Results: The mean bond strengths increased over storage time for all groups, except for the grit-blasted Au-Pt-Pd-Ag-In group. However, only in the grit-blasted and the primed groups for the Au-Ag-Cu-Pt alloy was this increase significantly different (P<.01). After 150 days of storage, the mean bond strength to Au-Ag-Cu-Pt alloy was 38.8 MPa without priming, whereas it was 40.6 to 40.8 MPa with the use of the primers. After the same time, the mean bond strength to the Au-Pt-Pd-Ag-In alloy was 20.6 MPa without priming, whereas it was 31. 9 to 37.8 MPa with the use of the primers. When comparing the different bonding methods and different storage times for the alloys, the superiority of the usage of both primers in combination was determined. Conclusion. The tested Alloy Primer significantly improved the bond strength of the dental adhesive resin cement (Panavia 21 Ex) to noble alloys. However, this effect depended on the alloy composition and was much greater for the Au-Pt-Pd-Ag-In alloy than for the Au-Ag-Cu-Pt alloy.

Statement of Problem: Problems with casting and porcelain bonding are encountered when titanium is used in metal-porcelain restorations. The oxidation characteristics of titanium are the main problem. The bonding mechanisms in titanium-porcelain systems are complex and poorly understood., Purpose: An in vitro investigation was performed to evaluate the bonding characteristics of 3 titanium-porcelain systems in various firing conditions., Material and Methods: This study evaluated the bonding strength of 3 commercial titanium porcelains fired in a vacuum and in an argon atmosphere to cast and noncast commercially pure titanium, using a 3-point bending test according to DIN 13927 and SEM with energy-dispersive spectrometry analysis. The results were compared with an Ni-Cr alloy and a conventional porcelain that was chosen as a control., Results: The Ni-Cr-conventional porcelain system fired in an argon atmosphere had significantly higher bond strength than the other systems (P<.001). In addition, the bond strength of the titanium-spark erosion-Noritake Ti22 combination, fired in an argon atmosphere, was significantly higher than the other titanium-porcelain groups, which had results similar to those obtained with the vacuum-fired, Ni-Cr-conventional porcelain and argon-fired titanium-cast-Noritake Ti22 groups. On the other hand, the bond strength of the titanium-TiBond and titanium-Vita Titankeramik groups was below the lower limit value in the DIN 13927 standard for the 3-point bending test (25 MPa). Although the results of the Duncan multiple range test showed that firing in an argon atmosphere did not affect the bond strength of the titanium-Vita Titankeramik groups, the titanium-spark erosion-TiBond group, or the titanium-cast-Noritake Ti22 group, argon firing improved the bond strengths of the Ni-Cr-conventional porcelain group, the titanium-cast-TiBond group, and the titanium-spark erosion-Noritake Ti22 porcelain group. It was also found that there were no significant differences between the bond strengths of cast and non-cast titanium groups; an exception was the titanium TiBond groups in which the porcelain was fired in a vacuum., Conclusion: The oxide layer produced on titanium was considered to have a potentially adverse effect on titanium-porcelain bonding. It was also concluded that matching the titanium-porcelain combination is the main determinant for optimal bonding. Firing in an argon atmosphere that limited the oxidation of titanium improved the titanium-porcelain bond in some of the groups.

Statement of Problem: Although the bond strengths of various resin composite luting materials have been reported in the literature, the evaluation of these systems with various cast alloys of different compositions has not been completely clarified., Purpose: To evaluate the tensile bond strength of sandblasted high-noble, noble, and base metal alloys bonded to etched enamel by 2 different bonding agents of different chemical composition: Panavia-Ex (BIS-GMA) and Super-Bond (4-META acrylic)., Material and Methods: Flat enamel surfaces were prepared on buccal surfaces of 60 extracted noncarious human incisors. Teeth were divided into 3 groups of 20 each. Twenty circular disks of 5 mm diameter were prepared for casting for each group. Group I was cast with a high-noble, group II with a noble, and group III with a base metal alloy. The surfaces of the disks were sandblasted with 250 microm Al(2)O(3). Ten disks of each group were bonded to exposed enamel surfaces with Super-Bond and 10 disks with Panavia-Ex as recommended by the manufacturer. The tensile bond strength was measured with an Instron universal testing machine with a crosshead speed of 0.5 mm/min until failure occurred., Results: Two-way ANOVA was used to evaluate the results. The differences in bond strengths of Super-Bond and Panavia-Ex with different alloys were not significant. The highest bond strengths were obtained in base metal alloys, followed by noble and high-noble alloys. These results were significant., Conclusion: Panavia-Ex and Super-Bond exhibited comparable tensile bond strengths. For both luting agents, the highest bond strengths were achieved with base metal alloys and the lowest with high-noble alloys.

The effect of experimental primers on the shear bond strength of polycarbonate composite resin with light-cured glass ionomer cements was investigated. Mixtures of methylmethacrylate (MMA) with the comonomers 2-hydroxyethyl methacrylate (HEMA), triethyleneglycol methacrylate (TEGDMA), and bisphenol-A-glycidymethacrylate (bisGMA) were used as primers. Polycarbonate composite resin rods of circular cross section and plates were bonded, with and without precured and nonprecured primers, using 2 light-cured glass ionomer cements (commercially available [LC] and experimental [EX]). In addition, commercial polycarbonate composite resin brackets with precured 50% TEGDMA/MMA primer were bonded to etched human enamel with both cements. Shear bond strengths were measured. Results were compared by ANOVA and Scheffe's tests at P = .05. The 30% HEMA/MMA, 50% TEGDMA/ MMA, 10% bisGMA/MMA, and 30% bisGMA/MMA primers produced the higher shear bond strengths (9.5 to 20.8 MPa) with LC and EX to polycarbonate composite resin. The 50% TEGDMA/MMA primer was most effective in improving the shear bond strengths of both LC and EX. Precured 50% TEGDMA/ MMA primer on a commercial resin bracket was effective in providing good shear bond strength to enamel.

The purpose of this study was to evaluate the shear bond strength and the site of bond failure for 2 visible light-cured composites (Transbond XT and Enlight) and a resin-modified glass ionomer cement (RMGIC; Fuji Ortho LC). Seventy-five extracted human premolars were collected and randomly divided into 3 test groups. Brackets were bonded to the teeth in each test group with the respective adhesive according to the manufacturers' instructions. Each specimen was debonded using an Instron Universal Testing Machine at a crosshead speed of 0.1 mm/min. The mode of bond failure was observed by using light microscopy. The results of this study demonstrated that the light-cured composites had a higher shear bond strength than the RMGIC. The adhesive-remnant scores were similar for the composites with the mean values at about 2, which indicates that more than half of the adhesive remained on the tooth. The RMGIC had a mean score of 3, which was significantly different from the composites and indicated that all of the adhesive remained on the tooth with a distinct impression of the bracket.

Statement of Problem: Although bonding to all-ceramic restorations is desirable, there is little information on the use of resin cements containing a phosphate monomer, and the importance of different surface treatments on their adhesion to high-strength core materials., Purpose: This study attempted to determine the shear bond strength values between Panavia 21 resin cement (Kuraray) and an alumina core material (In-Ceram) after 3 surface treatments and the application of a silane coupling agent., Material and Methods: Forty-five In-Ceram cylindrical rods were fabricated and assigned to 3 groups. Group I specimens were treated with a 9.5% hydrofluoric (HF) acid, group II with a 5% HF acid, and group III were sandblasted. All specimens were coated with a silane coupling agent (Cavex Clearfil Photobond and Activator) before cementation with Panavia 21 to sandblasted nickel-chromium rods. As a control, group IV consisted of 8 porcelain (Vitadur Alpha) rods treated with a 5% HF acid and silane. All specimens were subjected to a load of 1.2 kg during cementation, then stored under water for 36 hours. A jig mounted on a Hounsfield Universal Testing machine was used at a crosshead speed of 0.5 mm/min to test the shear bond strengths., Results: The results were 14.65 +/- 4.64 MPa for group I, 18.03 +/- 6.13 MPa for group II, and 22.35 +/- 5.98 MPa for group III In-Ceram specimens; and 18.05 +/- 8.46 MPa for control (group IV)., Conclusion: The use of Panavia 21 resin cement and a silane coupling agent can achieve a successful bond between either sandblasted or 5% HF acid-etched In-Ceram core material.

Background: Despite a lack of data based on clinical research, many positive characteristics have been attributed to the placement of amalgam restorations with an adhesive resin liner., Methods: For 42 months, and authors followed two groups of subjects who had amalgam restorations placed in a previous study. In this double-blind study, these subjects had been randomly assigned to have amalgam restorations placed with an adhesive liner or with a copal varnish placed under all restorations and a bulk base of zinc phosphate cement for deeper lesions. The authors evaluated anatomical form, marginal adaptation, retention and the presence of secondary caries at six, 18, 30 and 42 months., Results: At 42 months, the authors found that all restorations in both groups still were retained, were free of secondary caries and were rated clinically acceptable. No difference between the groups was found for any category (P > .05; analysis)., Conclusions: Placement of amalgam restorations with adhesive liners was found to produce results equivalent to that of traditional methods over a 42-month period., Clinical Implications: Practitioners wary of using new methods that have not undergone thorough clinical testing can feel comfortable placing adhesive liners under amalgam restorations.

Objectives: The aim of this in vivo study was to investigate the biocompatibility and microtensile bond strength of a one-application resin bonding system., Methods: Class V cavities were prepared on the facial surfaces of 36 intact monkey teeth, and the cavities were restored with an experimental one-application resin bonding system (TOF-1; Tokuyama Corp., Tokuyama, Japan) and a hybrid resin composite (PALFIQUE ESTELITE; Tokuyama Corp., Tokuyama, Japan). Histopathological changes of the restored teeth were evaluated at 3, 30 and 90 days after operation (N = 10). Microtensile bond tests were performed at 3 and 90 days after operation (N = 10)., Results: Only two of 30 pulps showed a slight inflammatory cell infiltration. There were no statistically significant differences in the incidence of slight inflammatory cell infiltration among time periods. Bacterial penetration along the cavity walls could not be detected in any specimen. The mean microtensile bond strength at 3 days after operation was 20.6 MPa, and that at 90 days was 14.9 MPa. Differences in bond strengths between the 3 day specimen and the 90 day specimen were statistically significant (p < 0.05)., Conclusions: The one-application resin bonding system exhibited acceptable biologic compatibility to the monkey pulp. Although there were statistically significant differences in bond strengths between the 3 day specimen and the 90 day specimen, this material provided a hermetic seal, eliminating bacterial microleakage.

Bonded retainers have become a very important retention appliance in orthodontic treatment. They are popular because they are considered reliable, independent of patient cooperation, highly efficient, easy to fabricate, and almost invisible. Of these traits, reliability is the subject of this clinical study. A total of 549 patients with retainers were analyzed with regard to wearing time, extension of the retainer, mean time between failures, operator, and age of patient. The average frequency of breakage or loss was 0.55 per retainer per year. This frequency was dependent primarily on the operator who bonded the retainer and on the extent of the retainer. If the upper canines were involved, reliability was lower. The majority of failures occurred during the first 3 to 6 months. The study showed that bonded retainers represent a highly efficient and reliable retention appliance suited to long-term use.

Statement of problem. Composite has been used to modify acrylic resin denture teeth. Purpose. This in vitro investigation examined the shear bond strengths between composite and autopolymerized acrylic resin bonded to acrylic resin denture teeth. Material and methods. The surface treatments used for the denture teeth included wetting with methyl methacrylate (MMA), vinylethyl methacrylate monomer (VEMA), unfilled liquid resin, composite bonding agent, and composite color modifier. Nonhydrated and hydrated denture tooth groups were included. A commercial composite was bonded to the denture teeth. The control group consisted of autopolymerized PMMA resin bonded to the acrylic resin denture teeth, and another group consisted of polyvinylethyl methacrylate bonded to acrylic resin denture teeth. The samples were thermocycled and tested in shear. Results. Acrylic resin denture teeth prewetted with MMA and treated with unfilled resin or a bonding agent had bond strength values comparable to the control group. VEMA was not as effective in promoting the bond. Composite color modifier did not produce a significantly weaker bond between the acrylic resin teeth and added composite. No prewetting of the teeth with MMA resulted in the lowest bond strength. Mean shear bond strengths for corresponding hydrated and non-hydrated groups were not significantly different. Conclusion. Bond strength of composite-to-acrylic resin denture teeth was comparable to the bond strength of autopolymerized acrylic resin.

Statement of Problem: New composites with improved qualities have been introduced to the dental profession as alternatives to porcelain. There is concern about the strength and reliability of new metal-resin bonding systems when these composites are used as esthetic veneers over metal frameworks., Purpose: This in vitro study compared the shear bond strength of 2 metal-resin bonding techniques with the bond strength of conventional porcelain fused-to-metal (PFM). Effects of water storage and thermocycling were also evaluated., Material and Methods: Ninety disks, cast in a medium gold, high noble PFM alloy, were divided equally into 6 groups, and received 3 treatments for veneering: conventional feldspathic porcelain on 1 group, and a composite (Artglass) bonded to the metal, using 2 metal-resin bonding techniques. Specimens were tested in shear, half of them after a 24-hour dry storage at room temperature and the rest after 10-day storage in normal saline solution at 37 degrees C and thermocycling. Fractured specimens were evaluated under x10 magnification to determine the nature of failure. Statistical analysis was performed with 2-factor analysis of variance (ANOVA)., Results: Mean shear bond strength values before and after wet storage and thermocycling were 29.66 and 22.91 MPa for the PFM group; 21.43 and 17.92 MPa for the Siloc group; and 19.34 and 15.64 for the etched group, respectively. The PFM group exhibited significantly higher bond strength values compared with the other 2 groups (P<.001). All groups showed a significant decrease in bond strength values after wet storage and thermocycling (P<.001)., Conclusion: Wet storage and thermocycling caused a significant decrease in shear bond strength of all specimens. Shear bond strength of conventional feldspathic PFM was significantly higher than that of the 2 metal-resin bonding techniques tested. The 2 latter techniques did not reveal any statistically significant differences.

Statement of Problem: There is little information regarding the mechanical and chemical retention of polymer-glass composite to cast titanium., Purpose: This study examined whether sandblasting in conjunction with silicoating improves the bond strength of the polymer-glass composite to cast titanium., Materials and Methods: Disk patterns (10 mm in diameter, 2.5 mm thick) were cast with commercially pure titanium (CP Ti) and Type IV gold alloy. Three pretreatments were applied: 50 microm Al(2)O(3) sandblasting (50 SB), 250 microm Al(2)O(3) sandblasting (250 SB), and 600-grit SiC paper polishing (600 SiC). After surface preparation, the Siloc system (silicoating) was applied on the disks. The 50 SB specimens without Siloc system were also prepared as controls. Then sticky tape with a circular hole (4.76 mm diameter) was placed onto the disk to define the bonding area. Artglass (polymer-glass) opaque, dentin, and enamel composites were applied using Teflon matrices and then light-polymerized. Shear bond strength (n = 8) was determined at a crosshead speed of 5 mm/min. Results were analyzed statistically with 2-way ANOVA and the Tukey-Kramer test (alpha=.05)., Results: The Siloc system significantly (P <.05) improved the mean shear bond strength of Artglass to both metals in the 50 SB specimens. Statistical differences (P <.05) in shear bond strength were found among surface treatments for the silicoated CP Ti specimens, in which 250 SB specimens yielded the greatest bond strength. The Type IV specimens treated with Siloc system showed no significant differences in shear bond strength between the 50 SB and the 250 SB specimens., Conclusion: Sandblasting with coarser alumina particles in conjunction with silicoating significantly enhanced bond strength of polymer-glass composite to cast titanium.

This study examined the effects of a number of patient and clinical variables on the breakage of bonded retainers, and consisted of a retrospective review of the survival of 200 bonded retainers. Data was collected from two clinical centres between November 1996 and February 1997. The subjects comprised 198 patients of both sexes divided into three age groups. Retainers at both centres were made in 018-inch co-axial wire with Relyabond and Helioprogress adhesives used at each respective centre. The effects on time to first breakage of adhesive, patient sex, and arch (upper/lower) were considered using Kaplan Meier survival graphs and in Log Rank Tests. Finally, a Cox Proportional Hazard Model was used to examine the joint effects of these factors and the patients' ages. Breakage over a 5-year period with Relyabond was 38.8 per cent upper, 22.1 per cent lower, and with Helioprogress 75 per cent upper and 23.2 per cent lower. Breakage appears to be unrelated to the materials used or to the age and sex of the patients. Upper retainers break more often than lowers (P = 0.016) and early breakage is more likely to occur at an adhesive pad than at a wire (9.6 versus 2.5 per cent within 6 months).

Under clinical situations, the intervals between material mixing and light exposure during bracket bonding using light-cured resin-reinforced glass ionomer cement may vary for each individual bracket. This study evaluates the bond strength of light-cured resin-reinforced glass ionomer cement subjected to various time intervals between material mixing and subsequent light exposure. This investigation was conducted in two parts. The first part consisted of measuring the enamel surface temperature to define the conditions under which the second part of the study was carried out. One hundred fifteen subjects, 63 males and 52 females, participated in this study. The over-all mean temperature as measured with a noncontact infrared thermometer was 31.9 degrees C. The second part of this study assessed tensile and shear bond strengths of light-cured resin-reinforced glass ionomer cement subjected to immediate light exposure (time interval, 5 minutes) and bond strengths subjected to light exposure at 10, 20, and 40 minutes after material mixing. Light-cured resin-reinforced glass ionomer cement was then compared with light-cured composite resin. Mean tensile and shear bond strengths of light-cured resin-reinforced glass ionomer cement exposed after 40 minutes were 4.5 MPa and 20.5 MPa, respectively. This represented a reduction of approximately 20% when compared with the 5-minute group. Scheffé test showed no statistically significant differences between any two time intervals. Mean bond strengths of the light-cured resin decreased with time. Tensile and shear bond strengths of light-cured resin indicated high statistical significance within groups across time. It could therefore be concluded that the bond strength of light-cured resin-reinforced glass ionomer cement was not affected by the timing of visible light exposure; whereas, the bond strength of light-cured resin decreased as time intervals increased. Light-cured resin-reinforced glass ionomer cement may thus serve as an advantageous alternative to composite resin for bracket bonding.

This study determined the bond strengths of porcelain bonding systems joined to a ceramic material, with the aim of evaluating the effect of a catalyst for silane coupling as well as that of initiators for bonding agents. Two sizes of specimen were cut from ceramic blocks (Cerec 2 Vitablocs Mark II) and then primed with either a three-liquid self-curing bonding agent (Clearfil Porcelain Bond, CPB), a three-liquid dual-activated bonding agent (Clapearl Bonding Agent, CBA), or their components. Unprimed specimens were also used as controls. After conditioning, the two different sized plates were bonded together with a dual-cured luting agent (Clapearl DC). The specimens were stored in 37 degrees C water for 24 h and shear bond strengths were determined. Shear testing revealed that the greatest bond strength was generated in the group consisting of ceramic material primed with CBA and exposed for 20 s prior to luting. Bond strengths of the CPB-primed group and the CBA-primed group without pre-exposure were comparable, whereas the remaining groups resulted in significantly lower bond strengths than the other three groups. The priming effect was greatly enhanced when a catalyst was used with the silane coupler as compared with the application of silane alone. The results suggest that incorporation of an initiator and a catalyst for silane coupling into the bonding agent reciprocally enhances bonding between the luting agent and the ceramic material.

Purpose: This study evaluated, in vitro, the capacity of a dentin bonding agent to improve the bond strength of orthodontic brackets using air abrasion enamel preparation., Methods: Each of the enamel surfaces received a different treatment prior to bonding procedures. Group 1 received acid-etched with 38% phosphoric acid for 30 seconds. Group 2 received acid-etched with 38% phosphoric acid for 30 seconds, dentin bonding agent (Scotchbond MultiPurpose) applied after rinse completed. Group 3 received abrasion-etched (particle size 50 microns, 120 psi). Group 4 received abrasion-etched, dentin bonding agent applied after etching completed. Unfilled adhesive resin (Ormco light cured sealant) was applied followed by a premolar bracket (Ormco meshed mini-twin) with adhesive (Ormco light cured adhesive) placed on the back. Shear bond strengths were measured using an INSTRON machine and the site of bond failure was determined under 3X magnification., Results: The shear bond strength obtained with a traditional acid-etch, in vitro, was not improved significantly by the use of a dentin bonding agent. Air abraded surfaces showed very low bond strengths with all treatments., Conclusions: Tested in vitro, air-abraded surfaces provide clinically unacceptable bond strength when compared to acid-etched enamel surfaces.

Shear bond strength of a composite resin adhesive (Concise) and two resin-modified glass ionomer cements (Fuji Ortho LC and Geristore) bonded to porcelain surface was tested. Orthodontic brackets were bonded to 120 porcelain disks (Finesse) etched with 9% HF. Samples were divided into six groups: (1) Concise, (2) Concise/silane, (3) Geristore, (4) Geristore/silane, (5) Fuji, (6) Fuji/silane. No statistical difference in mean shear bond strength was found between silanated Concise (15.8 MPa), Geristore (19.4 MPa), and Fuji (18.5 MPa) groups, which were significantly higher than nonsilanated groups. Porcelain fracture was observed in all silanated groups and nonsilanated Geristore group. We conclude that (1) silane increases bond strength to porcelain significantly for composite resin and resin-modified glass ionomer cement, (2) Concise, Geristore, and Fuji Ortho LC provide comparable shear bond strength to porcelain.

This study determined the influence of dentine structure on the micro-tensile bond strengths between resin and dentine of two different dentine adhesive systems (Single Bond, 3M Dental Products, St Paul, MN; MF-102 (experimental self-etching primer), GC Corporation, Tokyo, Japan). The study was separated into two main parts: bond strength measurement and investigation of the bonding interface. Twenty-two human premolars were used for the bond strength measurement. Each tooth was cut vertically, separating the tooth into mesio-distal halves. One half of the tooth was used to bond to a surface perpendicular to the dentinal tubules and other half to bond to a surface parallel to the tubules. For each half, six locations of dentine were bonded. Each material was used in accordance to the manufacturer's directions. Cylindrical hourglass-shaped specimens of 1.2 mm diameter at the bonded interface were manufactured. The bonds were stressed in tension at a crosshead speed of 1 mm/min. Mean bond strengths were compared using LSD, one-way ANOVA, and Student's t-test. The fractured surfaces were examined under a scanning electron microscope, and the frequency of fracture modes was compared using the Kruskal-Wallis and Mann-Whitney U tests. For the investigation of the bonded interface, four teeth were prepared by the same procedure used for the bond test specimens. The bonded interfaces were observed after an acid-base treatment or fracturing across the bonded interface, prior to investigation with a field-emission scanning electron microscope. For Single Bond, the bond strengths for mid-root dentine were significantly lower than for other locations (p < 0.05). For MF-102, there was no significant difference for all locations (p > 0.05). MF-102 bonded well to all locations of dentine while Single Bond showed a porous zone at the base of the hybrid layer. The bonds were not influenced by tubule orientation. The results indicate that the bond for Single Bond may be affected by its ability to penetrate demineralised dentine in different locations of a tooth. The self-etching primer of MF-102 produces a good bond and is independent of the position on the tooth.

During polymerization of resin composites, shrinkage stresses compete with resin-dentin bonds in a manner that can cause failure of the bond, depending upon the configuration of the cavity, its depth, and the restorative technique. The hypothesis tested in this study was that the effect of cavity configuration (C) and remaining dentin thickness (RDT) influence resin bond strength to the dentin of Class I cavity floors. The occlusal enamel was ground to expose a flat superficial dentin surface as a control (superficial dentin, C-factor = 1) in human extracted third molars. Cavities 3 mm long x 4 mm wide were prepared to a depth 2 mm below the ground dentin surfaces (deep dentin within cavity floor, C-factor = 3). To assess the relationship between C-factor and RDT, we removed the walls of cavities, making a deep flat surface for bonding (deep dentin, C-factor = 1). The teeth were restored with either Clearfil Liner Bond II (LB II), One-Step (OS), or Super-Bond D Liner (DL), followed by Clearfil Photo Posterior resin composite. After 24 hrs' storage in water, the teeth were sectioned vertically into 3 or 4 slabs (0.7 mm thick) and trimmed for the micro-tensile bond test so that we could determine the strength of the resin bonds to the pulpal floor. All groups gave high bond strengths to superficial dentin, but OS and DL gave significantly lower bond strengths to flat deep dentin when the C-factor was 1. When the C-factor was increased to 3 by the creation of a three-dimensional cavity preparation, the bond strengths of all materials fell (range, 21 to 35%), but the difference was significant (p < 0.05) only with DL. SEM observations of failure patterns showed that specimens with high bond strengths tended to exhibit cohesive failures within the hybrid layer, while specimens exhibiting low bond strengths showed failures at the top of the hybrid layer. Some adhesives do not bond well to deep dentin, making them more susceptible to polymerization shrinkage stress that develops in cavities with high C-factors.

The long-term durability of bonds between adhesive resins and dentin is of significant importance for the longevity of bonded restorations. We carried out an in vivo one-year study to evaluate the durability of resin-dentin bonds in the oral cavity, as well as to test the hypothesis that the adhesive interface would show morphological changes in vivo over time. Very shallow saucer-shaped dentin cavities were prepared in 12 intact teeth of one Japanese monkey (Macaca fuscata) under general anesthesia. The cavities were restored with Clearfil Liner Bond II and Clearfil Photo Posterior resin composite. The teeth were extracted at three different times: immediately, and 180 and 360 days after placement of the restorations. One day after the monkey was killed, specimens of the three time periods were subjected to the micro-tensile bond test at a crosshead speed of 1 mm/min. The surfaces of the failed bonds were observed under a field emission scanning electron microscope (FE-SEM). Bond strength measurements in this study were successfully performed and were stable at approximately 19 MPa during the one-year testing. Scanning electron microscopic observations of the failed surfaces revealed, at the top of the hybrid layer and within the adhesive resin, porosity which increased over time. Long-term bonds can be assessed in vivo by the combined evaluation of the microtensile bond strength and SEM morphological examination of the adhesive interface.

The purpose of this study was to evaluate in vitro the effect of water storage on the tensile bond strength of orthodontic brackets bonded with Vitremer and Fuji II LC resin-reinforced glass-ionomer cements. Seventy-two extracted human premolars were randomly divided into 6 groups and the bonding strengths of the resin-reinforced glass-ionomer cements were compared to control groups bonded with Concise composite resin at 24 hours and 9 months. The brackets were bonded on prepared teeth and a tensile load was applied to dislodge the brackets held in a special device from Lloyd 1000R testing machine. The effects of duration of water exposure, type of bonding material and interaction between long-term water exposure and type of bonding material on the bonding strength were described using the Weibull regression model. The mean tensile bond strength of resin-reinforced glass-ionomers after 24 hours water storage was significantly lower than the mean of the control samples. The results of this study showed no effect of water exposure on the tensile bond strength of brackets bonded with Vitremer glass-ionomer cement. The mean bonding strength of brackets bonded with Fuji II LC without enamel pre-conditioning significantly increased after 9-months water storage as compared to Fuji samples exposed to water for 24 hours. The results of this investigation allow to conclude: 1. Long-term water storage had not decreased the bond strength of resin-reinforced glass-ionomers applied as orthodontic adhesives, 2. Weibull regression model is an adequate and flexible tool to evaluate the bonding properties of dental materials.