Comparative Assessment of Bracket Bond Failure Rates of a Novel Chitosan-Based Orthodontic Primer: An In Vivo Split-Mouth Study.

Introduction An unavoidable side effect of orthodontic fixed appliance therapy is the demineralization of the enamel surface surrounding the bracket at the adhesive and tooth interface due to a microgap formation, which serves as a nidus for biofilm growth. Due to this, it is advantageous to include antibacterial agents in orthodontic primers without affecting their clinical properties. The aim of this study was to compare the in vivo bracket bond failure rates of a novel chitosan-based primer with a conventional orthodontic primer. Materials and methods Fifty-four subjects and 1,080 brackets were included in this study. At the end of six months, 45 subjects and 960 brackets bonded using novel chitosan-based primers and conventional primers (Anabond, Anabond Stedman Pharma Research Pvt Ltd, Chennai, India). Each was evaluated for a bracketed bond failure rate. Descriptive statistics and Chi-square tests were used for statistical analysis. Results The results revealed that the bracket bond failure rate in Group 1 (novel chitosan-based primer) was 27 brackets (3%) and 23 brackets in Group 2 (conventional primer) (2.5%), with no statistically significant difference between the two groups (p>0.05). There was a statistically significant difference in the bracket failure rate between the maxillary arch (2%) and the mandibular arch (3.5%) (p<0.05). Conclusion Brackets bonded with the chitosan-modified novel orthodontic primer showed no statistically significant difference in bracket bond failure rate when compared to the conventional primer. Bond failure rates were higher in the mandibular teeth when compared to the maxillary teeth.

Caries affected disinfection using Phycocyanin activated by PDT, Holy Basil, and Ti-sapphire laser on adhesive bond strength, microleakage, and bond failure.

AIM: To investigate the effect of different cavity disinfectants, Phycocyanin (PC), Ocimum Sanctum (OS), and Ti Sapphire Laser, on the bond integrity and microleakage of resin restorations. MATERIAL AND METHOD: 60 human mandibular molars were extracted and prepared based on ICDAS scores of 4 and 5. To obtain the CAD surface, a visual examination was supported by tactile sensation and a dye for caries detection. Samples were randomly allocated into 4 groups based on cavity disinfectants applied (n = 15). Group 1: Specimens disinfected with CHX, Group 2: Specimens disinfected with Ti sapphire laser, Group 3: Specimens disinfected with Phycocyanin activated by Photodynamic therapy, and Group 4: Specimens disinfected with OS. Following the disinfection of the CAD surfaces, composite bulk-fill restorative material was bonded to each specimen and all samples were subjected to thermocycling. Ten samples from each group underwent SBS testing performed on a universal testing machine. Five samples were subjected to a microleakage analysis. RESULT: The maximum microleakage scores were displayed by Group 3: PC (0.521 nm) treated specimens. Whereas, and minimum microleakage was exhibited by Group 4: OS (0.471 nm). Group 4: OS (23.06±0.21 MPa) treated group displayed the maximum bond scores of resin adhesive to the CAD surface. However, Group 3: PC (21.67±0.24 MPa) treated specimens exhibited the lowest bond scores. Failure mode analysis revealed that among all the investigated groups the predominant type of failure was cohesive failure i.e., Group 1 (80%), Group 2 (80%), Group 3 (70%), and Group 4 (90%). CONCLUSION: Ocimum Sanctum, Phycocyanin activated by Photodynamic therapy, and Ti-sapphire laser for disinfection of caries-affected dentin have shown promise in terms of improved bond strength and reduced microleakage.

FIBER REINFORCED COMPOSITE RETAINERS MAY BE AS EFFECTIVE AS MULTISTRANDED STAINLESS-STEEL WIRES IN FAILURE RATES AND MINIMAL ADVERSE EFFECT, BUT SUPERIOR IN TERMS OF RELAPSE AND PATIENT SATISFACTION.

ARTICLE TITLE AND BIBLIOGRAPHIC INFORMATION: Liu S, Silikas N, Ei-Angbawi A. Analysis of the effectiveness of the fiber-reinforced composite lingual retainer: A systematic review and meta-analysis. Am J Orthod Dentofacial Orthop. 2022 Aug 26:S0889-5406(22)00,432-2. doi: 10.1016/j.ajodo.2022.07.003. Epub ahead of print. PMID: 36,031,511. SOURCE OF FUNDING: Not reported. TYPE OF STUDY/DESIGN: Systematic review with meta-analysis of data.

Effect of self-etch primer application on the bond failure rate of a mandibular bonded lingual retainer.

BACKGROUND: The aim of this study was to examine the effect of self-etch primer (SEP) application on the bond failure rate of a mandibular bonded lingual retainer over 24 months. METHODS: The average age of the 86 individuals included in this study was 17 years 4 months. After the removal of the orthodontic appliances, the lingual retainers, which were made of six-stranded stainless steel wire, were bent and bonded onto the lingual surface of all mandibular anterior teeth. The study was performed using a split-mouth design. In the study group, the SEP was administered to the teeth's lingual surfaces. In the control group, they were etched using 37% phosphoric etchant liquid gel. After etching, the primer was applied. The adhesive resin was applied and the retainer was fitted. The patients were re-evaluated over 24 months. The first bond failures and the amount of adhesive remaining on the tooth were recorded as the adhesive remnant index (ARI) scores. The chi-square test was used to compare the bond failure rates (P = 0.231) and ARI scores between the groups (P = 0.162). The survival rates of the retainers were estimated using the Kaplan-Meier test (P = 0.237). The significance level was P < 0.05. RESULTS: The bond failure rates, ARI scores, and survival rates did not differ significantly between the groups. CONCLUSIONS: The results of this study demonstrated that an SEP can be used successfully in mandibular lingual retainer bonding. In situations where saliva isolation is difficult, bonding a fixed lingual retainer with SEP is recommended.

Comparative evaluation and influence of new Optibond eXTRa self-etch Universal adhesive and conventional Transbond XT on shear bond strength of orthodontic brackets-An in vitro study.

INTRODUCTION: The demand by dental practitioners for adhesives led to the innovation of newer self-etched universal adhesive systems. The objectives were to evaluate the shear bond strength (SBS) of metal brackets bonded with Optibond eXTRa Universal self-etch adhesive and Transbond XT primer and also to assess the adhesive remnant index (ARI). MATERIALS AND METHODS: A total of 100 extracted human premolar tooth samples were divided into 2 groups (n = 50) according to the adhesive system employed: Transbond XT (3M Unitek) and Optibond eXTRa Universal (KaVo Kerr). In group A, Transbond XT primer was applied, and in group B, Optibond eXTRa was applied, and metal brackets (American Orthodontics) were bonded with the Transbond XT adhesive, followed by photopolymerization with LEDition. The samples were preserved in artificial saliva for 30 days. SBS was tested using a universal testing machine (DAK Series7200, India). The ARI was assessed at 10× magnification under a stereomicroscope (Meiji Techno, Japan). The SBS scores were subjected to independent sample t-test and ARI scores to Pearson's Chi-square test. RESULTS: The mean SBS and standard deviation of Transbond XT is 12.11 ± 2.6 MPa and that of Optibond eXTRa Universal is 11.36 ± 2.8 MPa, revealing a statistically nonsignificant difference. Transbond XT displayed higher ARI scores and was statistically significant (P = 0.001). CONCLUSION: The Optibond eXTRa Universal adhesive appears to be preferable for orthodontic bonding as it exhibited clinically acceptable SBS and performed better in terms of the ARI.

Shear bond strengths of five porcelain repair systems to zirconia infrastructures.

Purpose: This study aimed to investigate the effect of five porcelain repair systems on shear bond strength in composite and zirconia infrastructures and to identify the bond failure mode after thermocycling. Materials and methods: Disk-shaped zirconia samples (n=50) were divided into five groups (n=10) according to repairing system type. Each repair system was applied to the zirconium samples and a hybrid composite was used for repairing. Shear bond testing of all groups was carried out using a universal testing machine after thermocycling. Results: Repair systems demonstrated no significant difference in repairing zirconia except Single Bond. Single Bond was the weakest in repairing the infrastructures. The highest and lowest mean bond strength values for the zirconia groups were 18,91 MPa and 3,63 MPa, respectively. Conclusion: The three repair systems, Ivoclar, Clearfil, and Bisco, were more effective than the Single Bond and Ultradent repair systems in repairing zirconia, and their bond failure modes were both mixed and adhesive.

A Comparative Assessment of Three Mandibular Retention Protocols: A Prospective Cohort Study.

PURPOSE: Fixed retainers have been advocated for the prevention of anterior mandibular crowding after orthodontic treatment. However, limited data is available to help clinicians choose a retention protocol that is acceptable in terms of stability, emergencies, and side effects in the long term. It was the aim of this study to assess survival and alignment stability of the 0.016" x 0.022" stainless steel wire compared to more common protocols. MATERIALS AND METHODS: Three different mandibular fixed retention protocols were compared in 600 consecutive patients: 1. 0.0215" multistrand wire (MW) with separate curing of resin and composite; 2. 0.016" x 0.022" stainless-steel wire with simultaneous curing of resin and composite (SS1C); and 3. 0.016" x 0.022" stainless-steel wire with separate curing of resin and composite (SS2C). The hazard rate for detachment across wire groups was assessed with a Cox frailty model. RESULTS: Incisor alignment was maintained with all retention wires. One incisor with unexpected torque change was observed in group MW. The average annual emergency rate was below 2% for all three protocols. Fewer emergency visits were found in patients with solid steel wires than with multistrand wires. Detachment of the wire is the most common cause of emergency visits with no difference between wire types. Multistrand wires were more often damaged than were solid steel wires. There was no evidence that direct application of the composite on the uncured primer influenced retainer adhesion to the enamel. CONCLUSIONS: The mandibular anterior teeth can be predictably stabilised with a 0.016" x 0.022" stainless steel wire..

Clinical and OCT assessment of application modes of a universal adhesive in a 12-month RCT.

OBJECTIVES: To evaluate a universal adhesive clinically using FDI criteria and by optical coherence tomography (OCT). METHODS: In 50 patients, three or four non-carious cervical lesions (NCCL) were restored with composite (Venus® Diamond Flow, Kulzer) using iBond® Universal (iBU, Kulzer) applied in self-etch (iBU-SE, n = 50), selective-enamel-etch (iBU-SEE, n = 29) or etch-and-rinse mode (iBU-ER, n = 50) and the reference OptiBond™ FL (OFL, Kerr, n = 50). Restorations were imaged by SD-OCT. The weighted mean length of interfacial adhesive defects (AD, %) was quantified per restoration immediately after placement (t0), simultaneously with clinical assessment (FDI criteria) after 14 days (t1), 6 (t2) and 12 months (t3). Data were statistically analyzed (McNemar-/Wilcoxon-/Mann-Whitney-U test (α = 0.05), Kaplan-Meier survival curves). RESULTS: After 12 months, cumulative failure rates were lower with iBU-SE (0.0%; p = 0.016), iBU-SEE (0.0%; p = 0.125), and iBU-ER (2.1%; p = 0.070; loss t3) compared to OFL (16.7%; losses t2, t3). Generally, marginal adaptation decreased (pi < 0.001) and marginal staining increased (pi ≤ 0.031), without significant group differences (pi > 0.064). AD increased in all groups (pi < 0.001). At enamel, AD appeared more extended with iBU-SE vs. iBU-SEE (t2-t3; pi ≤ 0.005), iBU-ER (t1-t3; pi ≤ 0.051) and OFL (t0-t3; pi ≤ 0.018). At dentin/cement iBU generally caused fewer defects than OFL (t1-t3; pi ≤ 0.010) and with SE vs. ER (t2-t3; pi = 0.010). CONCLUSIONS: In NCCLs, iBU generally provides a more durable bond than OFL. Recommended mode is SEE. Clinic and OCT provided comparable results. OCT has higher statistical power, shows group differences earlier and specifically for the different hard tooth tissues. CLINICAL SIGNIFICANCE: The universal adhesive iBU was superior against the reference OFL in NCCLs. It can be recommended with SEE. Evaluation of interfacial adhesive defects by OCT seems to allow early prediction of adhesives' clinical performance.

Orthodontic brackets debonding: evaluation of the time factor and the tooth type / Décollement des attaches orthodontiques : évaluation du facteur temps et du type de dent

Introduction: The aim of the study was to assess the time factor and tooth type during premature debond of orthodontic brackets. Material and Method: A retrospective epidemiological study was carried out on adolescents who had benefited from a multi-metal vestibular attachment treatment, having all 6 to 6 teeth bonded to the arch on the day of installation. Results: 333 patients were included. The detachment rate decreased as the treatment progresses. The teeth with most orthodontic debonding were the maxillary first molar, mandibular first molar, mandibular second premolar, and maxillary second premolar. Skeletal class II patients tended to take off more than class I patients. Detachments were significantly more frequent in the mandibular arch in deepbite compared to normalbite patterns, the mandibular second premolar being the tooth at risk. There seems to be a correlation between the quality of oral hygiene and the rate of detachment, regardless of the time of treatment. Discussion: The type of orthodontic movement, the quality of the bonding, the failure to observe the precautions by the patient may affect the date of the detachment. The low coronary height, hygiene, the biting force, the divergence seems to intervene on the type of attachment debonded. Conclusion: The brackets are more particularly debonded at the start of treatment and on the posterior teeth. Anteroposterior and especially vertical dysmorphosis could have an implication in debonding.

Introduction: L'objectif de l'étude était d'évaluer le facteur temps et le type de dent lors du décollement prématuré des attaches orthodontiques. Matériel et méthode: Une étude épidémiologique rétrospective a été réalisée sur les adolescents ayant bénéficié d'un traitement multi-attache vestibulaire en métal, ayant toutes les dents collées de 6 à 6 sur arcade le jour de la pose. Résultats: Au total, 333 patients ont été inclus. Le taux de décollement diminuait au fur et à mesure du traitement. Les dents avec le plus de décollements d'attaches orthodontiques étaient la première molaire maxillaire, la première molaire mandibulaire, la deuxième prémolaire mandibulaire et la deuxième prémolaire maxillaire. Les patients en classe II squelettique ont tendance à davantage décoller que les patients en classe I. Les décollements étaient significativement plus fréquents à l'arcade mandibulaire chez les hypodivergents que chez les mésodivergents, la deuxième prémolaire mandibulaire étant la dent à risque. Il semble exister une corrélation entre la qualité de l'hygiène buccale et le taux de décollement, quel que soit le moment du traitement. Discussion: Le type de déplacement orthodontique, la qualité du collage, le défaut d'observance des précautions par le patient peuvent intervenir sur la date de décollement. La hauteur coronaire faible, l'hygiène, la force de morsure, la divergence semblent intervenir sur le type d'attache décollé. Conclusion: Les attaches sont plus particulièrement décollées en début de traitement et sur les dents postérieures. Les dysmorphoses antéro-postérieures et surtout verticales pourraient avoir une implication dans le décollement.

[What are the risk factors specific to patient for debonding of orthodontic brackets?] / Quels sont les facteurs de risque de décollement des attaches orthodontiques propres au patient ?

The premature detachment of orthodontic brackets has consequences for the patient and the practitioner. While the responsibility for the bonding protocol has been widely assessed, the responsibility of the patient is poorly understood. The main objective of the study was to look for patient-specific predictors of metal vestibular attachment detachments. An historical cohort study was carried out from adolescents having benefited from a fixed vestibular appliance treatment lasting 27 months +/- 3 months, having all teeth from first molar to first molar on arch to pose. Univariate and multivariate analyses were performed by logistic regression. 333 patients were included. In univariate analysis, boys tended to take off more than girls, patients in skeletal Class II more than those in Class I, those with at least two cooperative remarks more than those with less than two remarks. The percentage of patients with debonding increases with the number of hygiene remarks. Younger patients were more prone to debond than older patients. The "age" factor has a significant effect in multivariate analysis. Neither the vertical skeletal pattern nor the socio-economic level would intervene in the rate of debonding. The role of patient-specific factors in detachment should be put into perspective. The reliability of the results would be increased by a prospective study using validated indicators of compliance.

"Clinical comparison of bond failure rate between two types of mandibular canine-canine bonded orthodontic retainers- a randomized clinical trial".

BACKGROUND: Bonded retainers are widely used as they are esthetically pleasing, easily acceptable, provide greater stability, compliance free and causes no soft tissue irritation and speech problems. Though, fracture and bond failure are their shortcomings. Therefore, the objectives of this study were to evaluate the number of bond failures and type of failure pattern between two types of mandibular canine-canine bonded retainers. METHODS: Total 60 subjects were recruited initially and were assessed for eligibility, out of which 6 were excluded and 2 were lost to follow up. They were randomly divided into two groups. Fiber reinforced composite (FRC) retainers were inserted in group 1 subjects while group 2 subjects received multistranded stainless steel (MSW) retainers. The subjects were recalled after every 3 months over a period of 1 year. Bond failure rate and failure pattern based on adhesive remnant index were evaluated at each visit. The bond failure rate and failure pattern were compared between the two retainers by using Chi-square test. RESULTS: The bond failure rates were 42.94% for FRC retainer and 31.41% for MSW retainer. Hence, total number of bond failures in both retainers were 37.17%. The difference of bond failure between two groups was statistically significant (p = 0.012). Type "0" failure pattern was detected commonly with both types of retainers (p <  0.001). CONCLUSION: Our findings indicate that multistranded stainless steel wire retainer is a superior option to be used for fixed lingual retention in mandibular arch as it exhibited lower bond failure as compared to fiber reinforced composite retainer. Adhesive failure is the most common type of bond failure observed with both types of fixed retainers. TRIAL REGISTRATION: ID NCT03881813 ( https://clinicaltrials.gov/ ); March 19, 2019, retrospective registration.

Photodynamic activation of irrigation (using different laser prototypes) on push out bond strength of fiber posts.

BACKGROUND: To evaluate the influence of photodynamic therapy (PDT) and light activated irrigation (LAI) using different laser prototypes Er,Cr:YSGG (ECYL), Er:Yag (EYL), Nd-Yag (NYL) on pushout bond strength of Pre-fabricated fiber reinforced composite (PFRC) post to radicular dentin. MATERIAL AND METHOD: Fifty maxillary and mandibular teeth were collected, cleaned and decoronated. Canals were instrumented using crown-down technique. Flaring of canals was performed using protaper S1, SX files. F1, F2 and F3 files were utilized for finishing of canal preparations. Prepared root canals were dried and obturated with gutta percha. Teeth were placed vertically within the section of polyvinyl pipes using acrylic resin. Post space preparation was completed using peso-reamers. Based on the PDT and laser activated irrigation (LAI) with different laser prototypes, samples were divided into five groups of 10 specimens each. Group 1- PDT, group 2-5.25 % NaOCl (sodium hypochlorite) and 17 % EDTA (ethylene diamine tetra acetic acid), group 3-5.25 % NaOCl with 17 % EDTA and NYL, group 4-5.25 % NaOCl with 17 % EDTA and EYL ; and group 5-5.25 % NaOCl +17 % EDTA and ECYL. Fiber post were luted in root canals with self-etch dual cure cement and teeth were sectioned at three levels (apical, middle and coronal). Push-out test was performed by placing the specimens in universal testing machine. Failure analysis of debonded surfaces was evaluated using stereomicroscope at 40× magnification. Means and standard deviations of push out bond strength were assessed by one-way analysis of variance (ANOVA). Comparison between means of push out bond strength was evaluated using Tukey multiple comparison tests (p = 0.05). RESULT: The highest push out bond strength was observed in group 5 at all three levels, coronal (10.08 ± 0.74 MPa), middle (8.95 ± 0.94 MPa) and apical (6.00 ± 0.88 MPa). The lowest push out bond strength was demonstrated by group 2 at all levels, coronal (6.15 ± 1.22 MPa), middle (5.65 ± 0.95 MPa) and apical (2.25 ± 0.55 MPa). Intra-group comparison showed decrease in push out bond strength in the coronal to apical direction among all investigated groups. Inter-group comparison exhibited comparable push out bond strength at all three levels of root for group 1 and group 2 specimens (p > 0.05). CONCLUSION: LAI with different laser prototypes improved push out bond values of PFRC post to root dentin as an adjunct to NaOCl and EDTA treatment. PDT improved push out strength compared to conventional canal cleaning regime.

Evaluation of the effect of ultraviolet light polymerized clear adhesive on shear and tensile bond strength of heat cure denture base resin to the cobalt-chromium retentive minor connector: An in vitro study.

AIM: The aim of this study is to evaluate the efficacy of new material ultraviolet (UV) light polymerized clear adhesive on shear and tensile bond strength of heat cure denture base resin (Polymethylmethacrylate (PMMA)) to cobalt-chromium (Co-Cr) retentive minor connector. SETTING AND DESIGN: Comparative evaluation- In-vitro study. MATERIALS AND METHODS: Sixty samples of Co-Cr plates mimicking minor connectors were fabricated. Thirty samples were coated with new material UV light polymerized clear adhesive and cured under UV light source for 10 min. In gun-metal flask, metal plates were placed in the lower compartment over it. Heat cure acrylic resin was packed in the dough stage with the help of clamps and processed according to the manufacturer's instructions. Samples were kept in artificial saliva for 90 days. Shear and tensile bond strengths were calculated of each sample with a Universal testing machine, and results were statistically analyzed. Type of bond failure was observed for each sample under stereomicroscope. STATISTICAL ANALYSIS USED: Unpaired t test. RESULTS: Tensile bond strength, as well as shear bond strength, showed that 0.93 N and 1.64 N respectively for without application of new adhesive was more as compared to that of samples with the application of new adhesive which is 0.75 N and 1.54 N respectively. Bond failure was found to be an adhesive failure in resin-metal interface. CONCLUSIONS: Excellent bonding seen between the new adhesive and acrylic interface but limited effect on the metal interface. To increase bond strength between metal and resin interface, some surface treatment with the metal surface is needed to increase the bonding of the new adhesive to the metal surface.

Evaluation of the effect of different surface treatments on the bond strength of non-precious alloy‒ceramic interface: An SEM study.

Background. Dental porcelain has excellent esthetics in combination with biocompatibility and is one of the most commonly used restorative materials. Its low tensile strength remains a major drawback. The porcelain-fused-to-metal restorations have been introduced to increase the fracture resistance of dental porcelain. The aim of this study was to evaluate the effect of different surface treatments on the bond strength of a non-precious alloy to ceramic. Methods. The present cross-sectional observational study was conducted with forty samples of cobalt‒chromium that were fabricated with porcelain interposed between the two metal test pieces. The metal was subjected to combinations of different surface treatments. The samples group A (n=10) were not subjected to any surface treatments. Group B samples underwent sandblasting and surface grinding. Group C samples were subjected to sandblasting, surface grinding and degassing; and group D samples underwent sandblasting, surface grinding, ultrasonic cleaning and degassing. The tensile bond strength was measured in a universal testing machine, and a scanning electron microscope (SEM) was used to obtain images of the samples after surface treatment to determine the surface irregularities and after the debonding of the samples for the type of the bond failure. ANOVA was used for the statistical analysis. Results. The results showed significant variations in the tensile bond strength between the four groups (F=251.05, P=0.000). The SEM images of group A showed no surface irregularities; group C samples exhibited surface irregularities more than those in group B. Group D had the highest surface irregularities. SEM evaluations showed a statistically significant difference in the type of bond failure (P<0.001). Conclusion. Based on the results of this study, it can be concluded that the surface treatments on the metal increased the bond strength of the metal‒ceramic interface significantly. A combination of sandblasting, surface grinding and ultrasonic cleaning, followed by degassing, resulted in the highest tensile bond strength.

Clinical and OCT outcomes of a universal adhesive in a randomized clinical trial after 12 months.

OBJECTIVES: To assess the performance of a universal adhesive in different application modes in non-carious cervical lesions clinically and by optical coherence tomography (OCT). METHODS: 55 adult patients with three non-carious cervical lesions (NCCL) each participated in the study. Lesions were restored with Scotchbond™ Universal (SBU, 3 M) applied in the self-etch (SBU-SE) and the selective-enamel-etch mode (SBU-SEE) in combination with Filtek™ Supreme XTE (3 M). OptiBond™ FL (OFL, Kerr) was used as a control. Restorations were clinically assessed (FDI criteria) after 14 days, 6 and 12 months and in parallel imaged by OCT (interfacial adhesive defects), starting immediately after filling placement. Cumulative failure rates (CFR) and means of interfacial adhesive defect were statistically evaluated. RESULTS: After 12 months, CFRs were lower in the SBU groups (0.0% each) than in the OFL group (20.0%, p = 0.001). Clinically, small marginal fractures occurred three times more often in the SBU-SE than in the SBU-SEE group (p = 0.001). Immediately after filling placement and at each reassessment OCT revealed more interfacial defects at enamel interfaces for SBU/SE compared to SBU/SEE and OFL (pi ≤ 0.044). At dentin/cement more defects were seen with OFL compared to SBU/SE and SBU/SEE (pi ≤ 0.001). Before restoration loss, more interfacial defects appeared compared to remaining restorations (pimmediately/6M = 0.132/0.002). CONCLUSIONS: Clinical evaluation and OCT imaging revealed higher interfacial integrity for SBU in both application modes compared to OFL. OCT detected interfacial bond failures prior to clinical deterioration or restoration loss. CLINICAL SIGNIFICANCE: Scotchbond Universal showed an equivalent or improved bonding performance compared to the reference adhesive. Selective enamel etching is recommended. The parameter interfacial adhesive defect seems to be a valuable predictor for evaluation of adhesive restoration systems.

Survival of maxillary and mandibular bonded retainers 10 to 15 years after orthodontic treatment: a retrospective observational study.

BACKGROUND: The long-term evidence regarding failures of fixed retainers is limited and the aim of this cohort study was to assess the long-term risk of failure of one type of maxillary and two types of mandibular fixed lingual retainers. TRIAL DESIGN: Retrospective cohort study. METHODS: Eighty-eight patients in retention 10-15 years after orthodontic treatment were included. The type of failure; number of failures per tooth, per patient, and retainer; and adverse effects were assessed by (1) a questionnaire, (2) clinical examination, and (3) screening patients' clinical charts. Descriptive statistics were calculated and a Cox regression was used to assess possible predictors for mandibular retainer survival. RESULTS AND CONCLUSIONS: In the mandible, 47 (53.4%) .016″ × .022″ braided stainless steel retainers (SS) were bonded to all six anterior teeth, and 41 (46.6%) .027″ ß-titanium (TMA) retainers were bonded to the canines only. From the SS retainers 40.4% and of the TMA retainers 61% had no failures during the whole observation period. SS failures per retainer were 2.17 (3.15) vs. 0.66 (1.03) for TMA. The type of retainer was the only significant predictor for failure. In the maxilla, 82 (93.2%) .016″ × .022″ braided SS retainers were bonded to all four incisors and six retainers (6.8%) to all six anterior teeth. The latter group was not further analyzed due to the small sample size. From the retainers bonded to all four incisors, 74.4% had no failure during the whole observation period. SS average number of failures per retainer bonded to the four incisors was 1.14 (SD 2.93). Overall, detachments were the most frequent type of first failure followed by composite damage. From the original mandibular retainers 98.9% and of the original maxillary retainers 97.6% were still in situ 10-15 years after debonding. No adverse torque changes were observed. LIMITATIONS: Potential effects of selection bias, information bias, and attrition bias as well as possible confounding factors cannot be fully excluded in this study.

Design of quasibrittle materials and structures to optimize strength and scaling at probability tail: an apercu.

The objective in materials or structure design has been to maximize the mean strength. However, as generally agreed, engineering structures, such as bridges, aircraft or microelectromechanical systems must be designed for tail probability of failure less than 10-6 per lifetime. But this objective is not the same. Indeed, a quasibrittle material or structure with a superior mean strength can have, for the same coefficient of variation, an inferior strength at the less than 10-6 tail. This tail is unreachable by histogram testing. So, one needs a rational theory, physically based and experimentally verified indirectly, which is feasible by size effect. Focusing on the results at the writer's home institution, this inaugural article (written three years ex post facto) reviews recent results towards this goal, concerned with quasibrittle materials such as concretes, rocks, tough ceramics, fibre composites, bone and most materials on the micrometer scale. The theory is anchored at the atomic scale because only on that scale the failure probability is known-it is given by the frequency of breakage of bonds, governed by the activation energy barriers in the transition rate theory. An analytical way to scale it up to the macroscale representative volume element (RVE) has been found. Structures obeying the weakest-link model are considered but, for quasibrittle failures, the number of links, each corresponding to one RVE, must be considered as finite. The result is a strength probability distribution transiting from Weibullian to Gaussian, depending on the structure size. The Charles-Evans and Paris laws for subcritical crack growth under static and cyclic fatigue are also derived from the transition-rate theory. This yields a size-dependent Gauss-Weibull distribution of lifetime. Close agreement with numerous published test data is achieved. Discussed next are new results on materials with a well-defined microscale architecture, particularly biomimetic imbricated (or staggered) lamellar materials, exemplified by nacre, a material of astonishing mean strength compared to its constituents. This architecture is idealized as a diagonally pulled fishnet, which is shown to be amenable to an analytical solution of the strength probability distribution. The solution is verified by million Monte Carlo simulations for each of the fishnets of various shapes and sizes. In addition to the classical weakest-link and the fibre-bundle models, the fishnet is found to be the third strength probability model that is amenable to an analytical solution. The nacreous architecture is shown to provide an additional major (greater than 100%) strengthening at the 10-6 failure probability tail. Finally, it is emphasized that the most important consequence of the quasibrittleness, and also the most effective way of calibrating the 10-6 tail, is the size effect on the mean structural strength, which permeates all formulations.

Evaluation of Bond Failure Rate of Orthodontic Brackets Bonded with Green Gloo-Two Way Color Changes Adhesive: A Clinical Study.

BACKGROUND: Bonding is an important step in fixed orthodontic mechanotherapy. Many new materials introduced an adhesive for bonding. This study was designed to evaluate the clinical bond failure rate of orthodontic brackets bonded with green glue: two way color changes adhesive and transbond XT adhesive paste. METHODS: Eighteen male patients with a mean age of 16 years were included in the study. Convenience sampling technique was used to select the sample for this study. The split-mouth design was used to bond 360 brackets by one operator and both adhesives were used in each patient. Bond failure rates were estimated with respect to bonding procedure, dental arch, tooth type (incisor, canine, and premolar). The results were evaluated using the chisquare test. Kaplan - Meier analysis and the log rank test were used to estimate the survival rate of the brackets. Bracket failure rates for each system were analyzed, and failure causes as reported by the patients and the quadrant of each tooth in which brackets failed were recorded. RESULTS: The bond failure rate was 5.00% and 4.44% for green gloo and transbond XT group. No significant difference was found in the bond failure rate between transbond XT and Green gloo group. No significant difference was found in the bond failure rate between the two groups, in relation to right and left side and the type of teeth. CONCLUSION: Green gloo adhesive can be effectively used to bond orthodontic brackets.

Shear Bond Strength and Bonding Properties of Orthodontic and nano Adhesives: A Comparative In-Vitro Study.

INTRODUCTION: Nano restorative composites have been successfully used in restorative dentistry and have high strength and wear resistance. Conventional orthodontic adhesives also possess optimal strength to withstand occlusal forces. This study was done to compare the shear bond strength (SBS) of orthodontic bracket after bonding with nanorestorative composite and orthodontic adhesives. MATERIALS AND METHODS: This in-vitro experimental study used sixty extracted teeth (divided into two groups). In Group A (n = 30), the brackets were bonded with Filtek Z350 (3M/Unitek, Monrovia, California, USA), a nano ceramic restorative composite, and in Group B (n = 30), the brackets were bonded with Transbond XT (3M/Unitek, Monrovia, California, USA), a conventional orthodontic adhesive. The SBS of the orthodontic brackets was measured using a universal testing machine. The modified 0-5-scale adhesive remnant index (ARI) was used to assess the amount of adhesive on enamel and bracket surfaces. The surface topography was observed to evaluate enamel damage. RESULTS: The mean (standard deviation [SD]) SBS of 11.07 (1.96) Mega Pascal (MPa) was observed with Filtek Z350, whereas the group bonded with Transbond XT showed the mean (SD) SBS of 12.18 (1.69) MPa. The results showed that Transbond light curing adhesive produced higher SBS than Filtek, but the difference was statistically insignificant (P = 0.088). The comparison of ARI score between the two groups also showed statistically insignificant difference (χ2 = 4.764, df = 5, P = 0.445), and most of the teeth in both groups exhibited score 3 (63%), showing the least damaging mode of bond failure to the enamel bracket interface. CONCLUSION: There was no significant difference in the mean SBS of Filtek Z and Transbond XT adhesives. Both materials showed optimum bond strength to withstand occlusal forces.

Comparative Evaluation of Two Bis-GMA Based Orthodontic Bonding Adhesives - A Randomized Clinical Trial.

INTRODUCTION: Of the various orthodontic bonding materials, orthofix is a fairly new entrant into this field. This material was exclusively introduced for orthodontic bonding purposes; however, the application of this material for orthodontic purpose has not been scientifically evaluated so far. AIM: The aim of the present study was to evaluate by an in-vivo double blinded split mouth rando mized clinical trial, the overall bond failure rates of two Bis-GMA based composite materials namely Transbond XT and Orthofix. MATERIALS AND METHODS: Thirty three participants who fulfilled the inclusion criteria were randomly allocated by lottery method into two groups. Group A participants had maxillary right and the mandibular left quadrants bonded using Orthofix and the remaining quadrants were bonded using Transbond XT. In Group B, the quadrants were reversed. Both groups were followed for a period of six months and were reviewed every 3-4 weeks. If a bond failed, the details were recorded and the duration of treatment before each breakage was calculated. Data were analyzed using Independent t-test and chi-square test. (p< 0.05) at 90% power. RESULTS: The overall bond failure rate for 263 brackets was 2.7% for Orthofix and 3.6% for Transbond XT. The mean esitmated survival time was 221.58 days for Transbond XT and for Orthofix was 220.07 days. The difference between these mean values were statistically insignificant (p>0.05). Similarly, failure rates of the anterior and posterior segment were compared and no difference was observed between the groups (p>0.05). The maxillary and mandibular teeth were compared and more failures were found in the mandibular teeth among both the groups but they were not statistically significant (p>0.05). CONCLUSION: The overall bond failure rate and mean survival time for Transbond XT was similar to Orthofix with no statistically significant difference.