Exploring access cavity through non-carious cervical lesions: Impacts on instrumentation, obturation, and fracture resistance in mandibular incisors.

AIM: To compare the effects of Cervical Access Cavity (CervAC) and Traditional Access Cavity (TradAC) on root canal preparation, root canal filling, and fracture resistance in mandibular incisors. METHODOLOGY: Twenty recently extracted and intact mandibular incisors were initially scanned using a micro-CT device. The specimens were anatomically matched to create two groups (n = 10). A wedge-shaped non-carious cervical lesion (NCCL) was created on the buccal aspect of all teeth using a double-faced segmented diamond disc. In group 1, a TradAC was prepared, whilst in group 2, access was created through the simulated NCCL using a round diamond bur 1012. After root canal preparation with Rotate instruments sizes 15/0.04, 20/0.04, and 25/0.04, the teeth were scanned again and evaluated for root canal volume and surface area, static voxels, volume of removed dental tissue, and dentine thickness. After that, the root canals were filled using the single-cone technique, teeth were restored with composite resin, and subsequently rescanned to calculate the volume of filling materials and voids. Then, the restored teeth were subjected to fracture resistance tests using a universal testing machine. Statistical comparisons between groups were performed with the Mann-Whitney test or the Student's t-test, with a statistical significance level of 5%. RESULTS: Statistical comparisons indicated no significant differences between groups in terms of root canal volume, surface area, static voxels, removed root dentine, root canal filling volume, percentage of voids, or fracture resistance load (p > .05). Conversely, teeth prepared with TradAC showed a significantly higher percentage of dental tissue removed from the crown (p = .001) and a greater volume of filling material remnants in the pulp chamber (p < .001) compared to the CervAC group. A significantly lower percentage reduction in dentine thickness was observed only on the mesial aspect of root at Level 1 in TradAC group (p = .008). CONCLUSIONS: CervAC can be considered a viable alternative approach in the presence of NCCL in mandibular incisors.

Prolonged polymerization of a universal adhesive in non-carious cervical lesions: 36-month double-blind randomized clinical trial.

OBJECTIVE: To evaluate the effect of prolonged (P) polymerization time of a universal adhesive system applied in etch-and-rinse (ER) or self-etch (SE) strategies on the clinical performance of restorations in non-carious cervical lesions (NCCLs), after 36 months of clinical service. METHODS: A total of 140 restorations were randomly placed in 35 subjects according to the polymerization time groups: ER (10 s); ER-P (40 s); SE (10 s); and SE-P (40 s) at 1,200 mW/cm2. Composite resin was placed incrementally. The restorations were evaluated immediately and after 6, 12, 18, and 36 months using the FDI criteria. Data were analyzed using the Kaplan-Meier survival test for retention loss, and the Kruskal-Wallis' test for secondary outcomes (α = 0.05). RESULTS: After 36 months, 19 restorations were lost: ER 6, ER-P 2, SE 9, SE-P 2. The retention rates were 82.3% for ER; 94.1 % for ER-P; 73.5 % for SE; and 94.1 % for SE-P, with a significant difference between ER vs. ER-P and SE vs. SE-P, as well as ER vs. SE-P and ER-P vs. SE (p < 0.0001). Minor defects were observed in 18 restorations for the marginal staining criteria: ER 5, ER-P 2, SE 8, SE-P 3; and in 33 restorations for the marginal adaptation criteria: ER 11, ER-P 4, SE 12, and SE-P 6 (p > 0.05). No restorations showed recurrence of caries or postoperative sensitivity. CONCLUSIONS: A prolonged polymerization time of 40 s improves the clinical performance of the universal adhesive for both adhesive strategies evaluated, even after 36 months. CLINICAL SIGNIFICANCE: Prolonging the polymerization time of a universal adhesive from 10 to 40 s has been shown to improve its clinical performance when used in NCCLs.

48-month clinical evaluation of a copper-containing universal adhesive in non-carious cervical lesions: A double-blind randomised clinical trial.

OBJECTIVES: This study aimed to evaluate the effect of copper nanoparticles (CuNp) on the clinical performance of a universal adhesive system used as an etch-and-rinse or self-etch strategy. METHODS: A total of 216 class V (non-carious lesions) restorations were randomly placed in 36 subjects according to the following groups: ERcu, adhesive in etch-and-rinse with 0.1% CuNp; ERct, adhesive in etch-and-rinse without CuNp; SEcu, adhesive in self-etch with 0.1% CuNp; and Sect, adhesive in self-etch without CuNp. Restorations were evaluated at baseline and at 6, 12, 18, 36, and 48 months, using the FDI and USPHS criteria. Appropriate statistical analyses were performed (α = 0.05). RESULTS: After 48 months, 14 restorations were lost (two for ERcu, five for SEcu, and seven for SEct) and the retention rates (95% confidence interval [CI]) were 74.1% for ERcu (95% CI 61.1-83.8); 81.5% for ERct (95% CI 69.2-89.6); 64.8% (95% CI 51.5-76.2) for SEcu; and 64.8% (95% CI 51.5-76.2) for SEct, with statistical differences between SEct vs. ERct and SEcu vs. ERct (p < 0.05). No significant differences between the groups were observed when the secondary parameters were evaluated (p > 0.05). Nineteen restorations (two for ERcu, two for ERct, six for SEcu, and nine for SEct) showed minor marginal staining, and 44 restorations (7 for ERcu, 8 for ERct, 14 for SEcu, and 15 for SEct) presented minimal marginal adaptation defects. SIGNIFICANCE: This is the first long-term clinical trial to show that the addition of CuNp to a universal adhesive system does not affect clinical performance.

Eighteen-month clinical evaluation of a new universal adhesive applied in the "no-waiting" technique: a randomized clinical trial.

OBJECTIVE: The aim of this double-blind, randomized clinical trial was to evaluate the 6- and 18-month clinical performances of a new universal adhesive applied in the "no-waiting" (NW) technique to non-carious cervical lesions (NCCLs) using two evaluation criteria. MATERIALS AND METHODS: One hundred and seventy-six restorations were assigned to four groups according to the adhesive system, adhesive strategy, and application mode: Prime&Bond Active (PB) applied using the etch-and-rinse (ER) and self-etch (SE) strategies with 20 s applications and Clearfil Universal Bond Quick (CQ) applied using the ER and SE strategies with the NW technique. The composite resin restorations were evaluated at baseline and after 6 and 18 months using the World Dental Federation (FDI) and US Public Health Service (USPHS) criteria. The Friedman repeated measures analysis of variance and Wilcoxon test were used for statistical analyses (α = 0.05). RESULTS: No significant differences were observed among any of the groups or criteria after 6 months (p > 0.05). After 18 months, 10 restorations were lost (p > 0.05) (2 with PB-ER [95.5%; 95%CI: 92-100%], 4 with PB-SE [90.9%; 95%CI: 82-98%], 0 with CQ-ER [100%; 95%CI: 92-100%], and 4 with CQ-SE [90.9%; 82-98%]). The restorations performed with the SE strategy showed more marginal discrepancies than those performed with the ER strategy, mainly when the FDI criteria were used (p < 0.05). Those that used the PB-SE showed fewer marginal discrepancies than those that used the CQ-SE (FDI; p < 0.05). A few restorations showed marginal discrepancies after the USPHS analysis (p > 0.05). CONCLUSIONS: The results when using the CQ-SE and -ER strategies with the NW technique were similar to those when using the PB-SE and -ER strategies in standard applications to non-carious cervical lesions after 6 and 18 months of clinical evaluation. CLINICAL RELEVANCE: After 6 and 18 months, the application of Clearfil Universal Bond Quick with the "no-waiting" technique showed similar clinical performance compared to the standard application of Prime & Bond Active applied using the standard application time (20 s). TRIAL REGISTRATION: ClinicalTrials.gov identifier RBR-5f9gps.

Three-year evaluation of different adhesion strategies in non-carious cervical lesion restorations: a randomized clinical trial

Abstract: Objective: To evaluate non-carious cervical lesions (NCCLs) restored with different adhesion strategies. Methodology: This is a prospective, randomized, double-blind, split-mouth study. An adhesive restorative system (Single Bond Universal/Filtek Z350XT - SBU) was evaluated both without and with selective enamel conditioning (E-SBU), resin-modified glass-ionomer cements (Vitremer; RMGIC), and ethylenediaminetetraacetic acid pretreatment (EDTA; E-RMGIC). In total, 200 restorations, placed in 50 patients, were evaluated at baseline and at a 3-year follow-up using the modified United States Public Health Service (USPHS) criteria. Data were analyzed using the two-proportion equality test, multinomial logistic regression, Wilcoxon test, and Kaplan-Meier survival curves. Results: In total, 42 (84%) patients returned for the 3-year follow-up. SBU showed restoration losses statistically different from RMGIC. Retention was also statistically different in SBU between baseline and the 3-year follow-up. Marginal defects and surface texture were statistically significant for all groups in the period studied, except for the surface texture of SBU and the marginal integrity in E-RMGIC. We observed no statistically significant difference in wear, secondary caries, anatomical form, surface staining, and color over time. Recession degree was the only factor to influence retention rates. Cumulative survival (%) was 89, 98, 98, and 95.3, for SBU, SE-SBU, RMGIC, and E-RMGIC, respectively, without significant differences among them. There was a statistically significant difference between survival curves; however, multiple comparison procedures found no statistical differences. Conclusion: Selective enamel etching affected the retention of non-carious cervical restorations. Adhesion using EDTA and resin-modified glass-ionomer cements delayed marginal defects over time. The degree of gingival recession influenced retention rates. Resin composite restorations showed initial marginal defects, and ionomer restorations, reduced surface luster. EDTA pre-treatment followed by resin-modified glass-ionomer cements may be a promising adhesion strategy for NCCL restorations.

Low-power laser and potassium oxalate gel in the treatment of cervical dentin hypersensitivity-a randomized clinical trial.

OBJECTIVE: To evaluate the effectiveness of different protocols for the treatment of cervical dentin hypersensitivity (CDH) in non-carious cervical lesions (NCCLs). MATERIALS AND METHODS: The CONSORT checklist was used to design this study. The sample with n = 74 participants (389 NCCLs) was randomly allocated into three groups: G1, potassium oxalate (Oxa-Gel BF); G2, GaAlAs (gallium-aluminum-arsenate) low-power laser (100 mW, 808nn, 60 J/cm2); and G3, potassium oxalate (Oxa-Gel BF) associated with the GaAlAs low-power laser. The CDH was triggered by the evaporative stimulus test (EST) and by the tactile stimulus test (TST). The visual analog scale (VAS) was used to quantify the degree of CDH. Changes in sensitivity were assessed from baseline over 3 weeks. Data were analyzed for NCCLs using mixed-effects models with unstructured direct product covariance structure (α = 0.05). RESULTS: After the first application, participants from G1 and G3 had a reduction in CDH (p < 0.05) compared with group G2 for TST. After the second application, G3 participants had a reduction in CDH (p < 0.05) in relation to G2 for both stimuli. Reduction in CDH (p < 0.05) occurred over 3 weeks for EST and TST for all groups; however, there was no difference between groups at the end of the therapies. CONCLUSION: Potassium oxalate was more effective in reducing immediate CDH. After four applications, all groups showed similar results for the reduction of CDH. CLINICAL RELEVANCE: GaAlAS laser irradiation and oxalate potassium gel could reduce the symptoms of CDH; thus, they are viable alternatives for the treatment of this condition. Chemical occlusion of dental tubules showed effective results after a shorter time interval. TRIAL REGISTRATION: Brazilian Clinical Trials Registration Platform under protocol number RBR-4ybjmt. http://www.braziliantrials.com/?keywords=RBR-4ybjmt&order=%7Eensaios.patrocinador_primario.

Root coverage of gingival recessions with non-carious cervical lesions: a controlled clinical trial.

OBJECTIVE: The non-carious cervical lesion (NCCL) is commonly produced by improper toothbrushing techniques, occlusion trauma, anatomic mal-positioned teeth, and acid erosion, thus sharing the same etiology of gingival recession (GR). The association of a graft to the coronally advanced flap had demonstrated the best long-term outcome for root coverage (RC). However, substitutes for the autogenous graft must be studied. This split-mouth clinical trial investigates the RC and the increase in keratinized tissue (KT) when comparing RC of NCCLs associated with GR with intact roots using an extended coronally advanced flap (ECAF) associated with the acellular dermal matrix graft (ADMG), a connective tissue replacement graft. MATERIAL AND METHODS: Seventeen individuals with bilateral GR were included in the study. One side had a NCCL (TG) and the opposite root was intact (CG). All patients were treated with the ECDF associated with ADMG. All clinical parameters were assessed at baseline and 6 months postoperative. RESULTS: Root coverage means (CG, 69.5 ± 19 and TG. 72.2 ± 16.5; p value = 0.849570) were not significantly different between control and test groups. In addition, the KT had an increase in the follow-up period for both groups. CONCLUSION: GR associated with NCCLs can be successfully treated with the ECDF and ADMG. CLINICAL RELEVANCE: Patients frequently search for GR treatment due to cervical wear, root sensitivity, and compromising aesthetics. The NCCL participates with the same issues. The present study contributes to the literature that GR associated with NCCLs can be successfully treated with the ECAF and the ADMG.

Lesão Cervical não cariosa: uma abordagem clínica e terapêutica / Non-carious cervical injury: a clinical and therapeutic approach

As lesões cervicais não-cariosas (LCNCs) são problemas frequentes nos consultórios odontológicos. Possuem etiologia multifatorial e se caracterizam pela perda de esmalte na região cervical dos dentes, causando deficiência tanto funcional, quanto estética. Como consequência dessas lesões, existe a hipersensibilidade dentária, causada pela presença de fluídos no interior dos túbulos dentinários que atingem as terminações nervosas. Nesse sentido, o objetivo desta revisão de literatura foi realizar uma abordagem acerca das LCNCs, evidenciando os fatores etiológicos, suas consequências e a importância do correto diagnóstico e remoção do agente causador para a realização dos diferentes métodos de tratamentos. Diante dessa realidade, o tratamento varia de acordo com o diagnóstico do aparecimento dessas lesões, sejam elas causadas por fatores intrínsecos ou extrínsecos ou a união de ambos. Sendo de fundamental importância o controle dos mesmos para o sucesso do tratamento e uma maior longevidade das estruturas dentárias.

Non-Carious Cervical Injuries (NCCIs) are frequent problems in dental offices. They have a multifactorial etiology and are characterized by the loss of enamel in the cervical region of the teeth, causing both functional and aesthetic deficiencies. Because of these injuries, there is tooth hypersensitivity, caused by the presence of fluids inside the dentinal tubules that reach nerve endings. In this sense, the objective of this literature review was to conduct an approach about NCCI, highlighting the etiological factors, their consequences and the importance of the correct diagnosis and removal of the causative agent for the realization of the different treatment methods. In view of this reality, treatment varies according to the diagnosis of the appearance of these lesions, whether they are caused by intrinsic or extrinsic factors or the union of both. Being of fundamental importance the control of the same for the success of the treatment and a greater longevity of the dental structures.

18-month clinical evaluation of a copper-containing universal adhesive in non-carious cervical lesions: A double-blind, randomized controlled trial.

OBJECTIVE: This study aimed to evaluate the addition of copper nanoparticles (CuNp) on the clinical performance of a universal adhesive system used as etch-and-rinse (ER) and self-etch (SE). METHODS: 216 restorations were randomly placed in 36 subjects according to the following groups: ERcu = etch-and-rinse with 0.1% CuNp; ERct = etch-and-rinse without CuNp; SEcu = self-etch with 0.1% CuNp; SEct = self-etch without CuNp. Resin composite was placed incrementally and light-cured. The restorations were evaluated at baseline and 6, 12 and 18 months using the FDI and USPHS criteria. Statistical analyses were performed using appropriate tests (α = 0.05). RESULTS: The addition of CuNp did not increase the clinical performance (FDI / USPHS) of the universal adhesive tested after 18-month when applied in the ER mode (p > 0.05). The addition of CuNp in SE restorations increased the retention rate significantly and decreased the marginal discrepancies after 18 months (p < 0.05). CONCLUSION: The clinical performance of universal adhesive was significantly increased when applied in the SE mode with the addition of copper nanoparticles. CLINICAL RELEVANCE: This is the first study that demonstrates a slight improvement in the clinical performance of universal adhesive systems in non-carious cervical lesions when added CuNp in lower concentration.

One-year clinical evaluation of bulk-fill flowable vs. regular nanofilled composite in non-carious cervical lesions.

OBJECTIVE: The aim of this double-blind, randomized trial was to evaluate the 1-year clinical performance of a bulk-fill flowable and a regular nanofilled composite in non-carious cervical lesions (NCCLs). METHODS: Twenty-two subjects with at least two NCCLs were enrolled in the study. A total of 89 restorations were performed by a single operator using Filtek Supreme (FS) Ultra Universal or Filtek Bulk (FB) Fill Flowable. A universal adhesive (Scotchbond™ Universal Adhesive) was used with a self-etching approach in dentin. The restorations were evaluated by two independent and previously calibrated examiners at baseline (7 days), 6 months and 1 year, according to the USPHS modified criteria. Mann-Whitney U test was used to analyze the differences between composites and Wilcoxon signed rank test for comparisons between the baseline and follow-ups (α = 5%). RESULTS: One restoration was considered clinically unacceptable due to loss of retention after 6 months in the FS group. FS presented statistically high scores for surface roughness when compared to FB after 1 year (p < 0.05), but both were considered clinically acceptable. After 1 year, the frequency of clinically unacceptable rates was 3.3% for anatomical form in the FB group, 1.1% for retention in the FS group, and 2.2% for marginal adaptation in both groups. All restorations, in both groups, presented score 0 over the 1-year period for marginal staining, postoperative sensitivity, and secondary caries. CONCLUSION: Both composite resins showed acceptable clinical performances for the restoration of NCCLs after 1 year. CLINICAL RELEVANCE: Both bulk-fill flowable and regular nanofilled composites showed good clinical performances for the restoration of NCCLs after 1 year.

Nd:YAG laser and calcium sodium phosphosilicate prophylaxis paste in the treatment of dentin hypersensitivity: a double-blind randomized clinical study.

AIM: This double-blind, placebo-controlled, randomized clinical trial evaluated the effectiveness of Nd:YAG laser and a calcium sodium phosphosilicate-containing paste (NovaMin®) in the treatment of cervical dentin hypersensitivity (CDH). MATERIALS AND METHODS: Seventy patients were randomly allocated into the following experimental groups: control-placebo, calcium sodium phosphosilicate paste (NovaMin®), and Nd:YAG laser (1 W, 10 Hz, 85 J/cm2). Pain was evaluated by means of a visual analog pain scale (VAS) after evaporative stimulation with a jet of air and tactile stimulation with an exploratory probe, before treatment (baseline) and after 5 min, 1week, and 4 weeks. When patients presented more than one tooth with CDH, the mean of the values obtained was calculated. Irradiation with Nd:YAG laser was performed twice in the mesial-distal and twice in the occlusal-gingival direction. The NovaMin®-containing paste was applied with a rubber cup at low speed for 60 s. Patients of the placebo group received simulations of the two treatments. As the data presented normal distribution, the two-way ANOVA repeated measures test was used. RESULTS: In all the experimental times, reduction in pain was demonstrated in comparison with baseline for all treatments (p < 0.05); however, there was no difference among the experimental groups in any of the time intervals evaluated (p > 0.05). CONCLUSION: All treatments were equally effective in reducing the pain of CDH. CLINICAL RELEVANCE: Nd:YAG laser irradiation and the calcium sodium phosphosilicate paste could reduce the symptoms of CDH; thus, they stand out as viable alternatives for the treatment of this condition.

Comparison of the clinical effect of the adhesive strategies of universal adhesives in the treatment of non-carious cervical lesions: systematic review and meta-analysis

Objective: to compare, through a systematic review and a meta-analysis, the clinical effect of the adhesive strategies of universal adhesives (UA) in the treatment of non-carious cervical lesions (NCCLs). material and method: a search of the literature was carried out up to january 2018, in the biomedical databases: Pubmed, Embase, Scielo, Science Direct, SIGLE, LILACS, BBO, Google Scholar and the Central Register of Cochrane Clinical Trials. the selection criteria of the studies were as: randomized clinical trials, with a maximum age of 5 years and which report the clinical effects (marginal adaptation, discoloration or marginal staining, presence of secondary caries, postoperative sensitivity, retention and fractures) of the UA in the treatment of NCCLs. the risk of study bias was analyzed through the Cochrane Handbook of systematic reviews of interventions. results: the search strategy resulted in eight articles that reported no difference in marginal adaptation, discoloration or marginal staining, presence of secondary caries and postoperative sensitivity among the adhesive strategies of the UA; however they reported a difference between the retention and the presence of fractures, with the conventional adhesive strategy resulting in a better clinical effect. conclusion: the reviewed literature suggests that the conventional adhesive strategy of UAs results in greater retention and absence of fractures in the treatment of NCCLs.

Evaluation of different treatment protocols for dentin hypersensitivity: an 18-month randomized clinical trial.

This randomized and longitudinal in vivo study aimed to assess different protocols for the treatment of dentin hypersensitivity with low-power laser (with different doses), high-power laser, and a desensitizing agent, for a period of 12 and 18 months. The lesions from 32 patients (117 lesions), who were submitted to the inclusion and exclusion criteria, were divided into nine groups (n = 13): G1: Gluma Desensitizer (Heraeus Kulzer), G2: low-power laser with low dose (three points of irradiation in vestibular portion and an apical point 30 mW, 10 J/cm2, 9 s per point with the wavelength of 810 nm, with three sessions with an interval of 72 h), G3: low-power laser with high dose (one point in the cervical area, and one apical point 100 mW, 40 J/cm2, 11 s per point with the wavelength of 810 nm in three sessions with an interval of 72 h), G4: low-power laser with low dose + Gluma Desensitizer, G5: low-power laser with high dose + Gluma Desensitizer, G6: Nd:YAG laser (Power Laser™ ST6, Research® in contact 1.0 W, 10 Hz and 100 mJ, ≈85 J/cm2, with the wavelength of 1064 nm), G7: Nd:YAG laser + Gluma Desensitizer, G8: low-power laser with low dose + Nd:YAG laser, and G9: low-power laser with high dose + Nd:YAG laser. The level of sensitivity of each volunteer was assessed by visual analog scale of pain (VAS) with the aid of air from the triple syringe and exploration probe, 12 and 18 months after treatment. All analyses were performed separately for air and probe stimulus. The level of significance was considered for values of p < 0.05. After statistical analysis, all treatments were shown to be effective in reducing dentinal hypersensitivity, and the results were considered not statistically different from those at 12 months. Therefore, until the 18-month evaluation, it could be said that no statistical differences were observed in the sensitivity levels for all treatments.

Effects of non-carious cervical lesion size, occlusal loading and restoration on biomechanical behaviour of premolar teeth.

BACKGROUND: Information on fracture biomechanics has implications in materials research and clinical practice. The aim of this study was to analyse the influence of non-carious cervical lesion (NCCL) size, restorative status and direction of occlusal loading on the biomechanical behaviour of mandibular premolars, using finite element analysis (FEA), strain gauge tests and fracture resistance tests. METHODS: Ten buccal cusps were loaded on the outer and inner slopes to calculate the strain generated cervically. Data were collected for healthy teeth at baseline and progressively at three lesion depths (0.5 mm, 1.0 mm and 1.5 mm), followed by restoration with resin composite. The magnitude and distribution of von Mises stress and maximum principal stress were simulated at all stages using FEA, and fracture strength was also determined (n = 7 per group). RESULTS: There were significant effects of the lesion size and loading directions on stress, strain and fracture resistance (p < 0.05). Fracture resistance values decreased with increase in lesion size, but returned to baseline with restorations. CONCLUSIONS: Combined assessment of computer-based and experimental techniques provide an holistic approach to characterize the biomechanical behaviour of teeth with both unrestored and restored NCCLs.

Effect of EDTA conditioning on cervical restorations bonded with a self-etch adhesive: A randomized double-blind clinical trial.

OBJECTIVE: To compare the 18-month retention rates of composite restorations in non-carious cervical lesions [NCCLs] bonded with a self-etch adhesive with and without preliminary conditioning with EDTA. METHODS: Forty-eight patients with two similar-sized NCCL were selected and randomly allocated to one of two groups. Two calibrated operators placed 96 restorations with a one-step self-etch adhesive (Adper Easy One, 3M ESPE). Half of the restorations were placed according to the manufacturer's instructions while, for the other half, the surfaces of the lesions were conditioned with 17% EDTA for 2 min prior to adhesive application. Two blinded and independent examiners evaluated the restorations at baseline, 6, 12, and 18 months, according to the FDI criteria. The comparison between groups in each period was conducted with the Fisher's exact test, and the performance of each group at the different periods was evaluated by McNemar's test (α=0.05). RESULTS: After 18 months, significantly higher retention rates (95% CI) were observed for the EDTA group (95.5 [84.9-98.7]) than the control group (79.6% [65.5-88.9]) (p=0.02). Significant deterioration of the marginal adaptation and marginal discoloration were observed for both groups over the 18-month evaluation. CONCLUSIONS: The preliminary conditioning with EDTA before application of a one-step self-etch adhesive significantly improved the retention rates of composite restorations in cervical lesions. CLINICAL SIGNIFICANCE: Conditioning with EDTA is an alternative that improves the 18-month retention rate of cervical restorations bonded with a self-etch adhesive.

Influence of non carious cervical lesions depth, loading point application and restoration on stress distribution pattern in lower premolars: a 2D finite element analysis / Influência da profundidade da lesão cervical não cariosa, ponto de aplicação de carga e restauração no padrão de distribuição de tensões em pré-molares inferiores: 2d-análise por elementos finitos

The aim of this study was to analyze the biomechanical behavior of lower premolars regarding the non-carious cervical lesion (NCCL) depth, load type and restoration status, using finite element analysis. Twodimensional virtual model simulating a healthy lower premolar were created using the CAD software. Based on this image, five models were generated: healthy (H), three types of NCCLs: small lesion (SL ­ 0.5 mm deep), medium lesion (ML ­ 1.0 mm), deep lesion (DL ­ 1.5 mm), and restored lesion (RL). The models were export to a CAE software (ANSYS Finite Element Analysis Software), the areas of all structures were plotted and each model was meshed using a control mesh device. All of the virtual models were subjected to two occlusal load types, (100N each): occlusal load (OL) and buccal load (BL) on buccal cusp. The magnitude and the stress distribution were obtained using the von Mises and maximum principal stress criteria (1), in MPa. The quantitative analysis of stress (MPa) was identified at three points of the NCCLs: enamel surface on its upper wall , dentin at the bottom wall and dentin on the lower wall. The results showed a direct relation between sequential removal of cervical structure and higher stress concentration for any groups and for both loads types. For OL the highest value of stress was 8.8 MPa for DL on upper wall of NCCLs.The BL exhibited higher stress values in comparison to the OL for all models.In addtion, the BL was responsible for providing the highest stress accumulation on the bottom wall, 38.2 MPa for DL. The restoration with composite resin was able to restore a stress distribution close to the healthy model, for both load types. In conclusion, the extent of non-carious cervical lesion and loading conditions influenced the stress distribution pattern of lower premolar. The outer load seems to be more critical in affecting the biomechanical behavior of lower premolars, regardless of the lesion size. The restoration of NCCLs with composite resin appears to recover the biomechanical behavior, similar to healthy model.

O objetivo desse estudo foi analisar o comportamento biomecânico de pré-molares inferiores em relação a profundidade da lesão cervical não cariosa (LCNC), tipo de carregamento e condição da restauração, utilizando a análise por elementos finitos. Modelo virtual bidimensional simulando um pré molar inferior hígido foi criado utizando o software de CAD.A partir dessa imagem, cinco modelos foram gerados: hígido (H), três tipos de LCNCs-lesão rasa (SL-0.5 mm de profundidade), lesão média (ML-1.0mm), lesão profunda (DL-1.5mm), e lesão restaurada (RL). Os modelos foram exportados para o software de CAE (ANSYS Software de Análise por Elementos Finitos), as áreas de todas as estruturas foram plotadas e cada modelo foi malhado utilizando um dispositivo controle de malha.Todos os modelos virtuais foram submetidos a dois tipos de carregamento oclusal (100N cada): carregamento oclusal (OL) e carregamento externo (BL) na cúspide vestibular. A intensidade e a distribuição das tensões foram obtidas utilizando os critérios de von Mises e tensão máxima principal (1),em Mpa. A análise quantitativa das tensões (MPa) foi identificada em três pontos das LCNCs: parede superior em esmalte, parede de fundo em dentina e parede inferior em dentina. Os resultados apresentaram uma relação direta entre a remoção sequencial de estrutura na região cervical e os maiores valores de concentração de tensões para todos os grupos e para os dois tipos de carga. Para OL, o maior valor de tensão foi 8.8 MPa para DL na parede superior da LCNCs. O BL exibiu maiores valores de tensão em comparação ao OL para todos os modelos. Além disso, BL foi responsável por promover o maior acúmulo de tensão na parede de fundo, 38.2 MPa para DL. A restauração com resina composta foi capaz de restaurar uma distribuição de tensões similar a do modelo hígido, para ambos os tipos de carga. Em conclusão, a extensão da lesão e o tipo de carregamento influenciaram no padrão de distribuição de tensões de pré-molares inferiores. A carga externa parece ser mais crítica para afetar o comportamento biomecânico de pré-molares inferiores, independente do tamanho da lesão. A restauração das LCNCs com resina composta, parece recuperar o comportamento biomecânico similar ao do modelo hígido.

Non-carious cervical lesions: influence of morphology and load type on biomechanical behaviour of maxillary incisors.

BACKGROUND: The aim of this study was to measure the effect of simulating two different loads on maxillary incisors displaying eight morphological types of non-carious cervical lesions, unrestored and restored with an adhesive restoration, by quantifying the stress distributions generated using finite element analysis. METHODS: Virtual models of maxillary incisors were generated using the CAD software (RhinoCeros). After composing virtual dental and supporting structures with and without non-carious cervical lesions, each model was meshed using a control mesh device (ANSYS Finite Element Analysis Software). All of the virtual models were subjected to two load types, oblique load and vertical load, to simulate occlusal forces of 100 N each. Comparisons were made between simulated teeth with non-carious cervical lesions, with and without composite resin restorations, and a simulated sound tooth. Data summarizing the stress distributions were obtained in MPa using von Mises criteria. RESULTS: Oblique loading on simulated non-carious cervical lesions resulted in greater stress concentration compared with vertical loading, and non-carious cervical lesions with acute angles displayed higher stress concentrations at the depth of the lesion. Restoring the lesions with an adhesive restoration, such as composite resin, appeared to overcome this stress concentration. CONCLUSIONS: Restoring NCCLs with adhesive restorative materials, such as a nanohybrid composite resin, appears to recover the biomechanical behaviour similar to sound teeth.

Análise das tensões nos primeiros pré-molares superior e inferior, em contato, através do método de elementos finitos / Enamel stress distribution in superior and inferior premolars, in contact, through a finit elements study

As lesões cervicais não cariosas foram, durante muito tempo, atribuídas à abrasão causada pela escovação dental, e/ou por processos erosivos. Teorias biomecânicas consideram a possibilidade de que concentrações de tensões na região cervical, causadas pela flexão de cúspides, poderiam contribuir, associadas a outros fatores clínicos, para o desenvolvimento dessas lesões chamadas de abfração O presente trabalho pretende através do método de elementos finitos, utilizando o programa ANSYS versão 8.1, analisar a distribuição de tensões na região cervical de modelos bidimensionais parametrizados dos primeiros pré–molares superior e inferior quando estes são colocados em contatos cêntrico e excêntricos no plano frontal, sob uma carga de 1 N. Para simulação da diminuição da mobilidade do ligamento periodontal sob cargas de impacto, o valor real do seu módulo de elasticidade foi aumentado para o correspondente ao do osso esponjoso e ao do osso cortical. Os resultados permitiram concluir que, de uma maneira geral, nas posições excêntricas, os dentes se flexionam e tensões de tração ocorrem na região cervical oposta ao contato com valores compatíveis para formação das lesões. Na posição cêntrica, as tensões de tração se manifestam mais na região da fossa central de ambos os dentes e na cervical do pré-molar inferior. A simulação da diminuição da mobilidade dentaria sob cargas de impacto reduziu o valor das tensões de tração, em todas as regiões analisadas, na ordem de 33% para o pré-molar superior e 66% para o inferior, mas não alterou seu padrão de distribuição

Non carious cervical lesions were often attributed to toothbrush abrasion and/or erosive process. Biomechanical theories consider that stress concentration in the cervical area, caused by cuspal flexure, may contribue, associated to other clinical factors for the development of the lesion called abfraction. The aim of this finite element study, using the ANSYS version 8.1, is to analyze the stress distribution in the cervical region of superior and inferior premolars’ bidimensional models. Contacts in centric and eccentric positions were reproduced under a 1 N load. To simulate tooth mobility reduction under impact loads, the elastic modulus of the periodontal ligament was increased to reach the corresponding ones of the alveolar and cortical bone. The results showed that, in eccentric positions, teeth bend and tensile stress are generated at the cervical region opposed to the contact side, justifying the possibility to initiation of the lesion. In centric position, tensile stress occurred on both teeth at the central fossae and at the buccal cervical area of the inferior premolar. The simulation of tooth mobility reduction under impact loads diminished the tensile stress value, at all of the analyzed positions, in a rate of 33% and 66% respectively to superior and inferior premolars