Eight-year clinical evaluation of two types of resin composite in non-carious cervical lesions.

OBJECTIVES: In this clinical study, the 8-year clinical performances of a flowable resin composite was compared with that of a conventional resin composite. MATERIALS AND METHODS: Ninety non-carious cervical lesions (NCCLs) in 19 participants were involved in this trial. NCCLs were restored with a flowable composite (Clearfil Flow FX: FX, Kuraray Noritake, Japan) or a conventional resin composite (Clearfil AP-X: AP) in conjunction with a one-step self-etch adhesive (Clearfil S3 Bond). Each participant had both types of resin composite restorations that were randomly allocated. The restorations were evaluated at baseline and annually up to 8 years using modified USPHS criteria. The data were statistically analyzed using the Fisher's exact test, Kaplan-Meier method, and a multivariate Cox-regression with frailty models (p < 0.05). RESULTS: The 8-year participant recall rate was 95%. One hundred percent retention was recorded for AP, whereas four out of 46 restorations were lost for FX during the 8 years. The incidence of marginal staining increased over time regardless of the type of resin composite, showing 48% for AP and 57% for FX after 8 years. Wear of the resin composite occurred only for the flowable material and there was a significant difference between the types of resin composite (p = 0.024). Overall survival rates at 8 years for AP and FX were 98% and 82% respectively (p = 0.110). CONCLUSIONS: The flowable resin composite presented lower wear resistance and showed a lower survival rate compared with the conventional composite after eight years of clinical service. CLINICAL RELEVANCE: Flowable resin composites may show greater wear after long-term clinical service. TRIAL REGISTRATION NUMBER: UMIN000028745, Date of registration: August 19, 2017.

Progression of non-carious cervical lesions: 3D morphological analysis.

OBJECTIVES: This longitudinal study aimed to investigate morphologically and quantitatively the progression of non-carious cervical lesions (NCCLs) using a confocal laser scanning microscope (CLSM) and replica models. MATERIALS AND METHODS: The samples examined comprised sets of replicas annually obtained from 83 lesions in 16 participants over 3 to 5 years. All lesions were visually categorized as wedge-shaped, saucer-shaped, or mixed-shaped lesions. CLSM images of the replicas were analyzed in terms of axial depth, occlusogingival width (height) in the buccolingual cross-section, and estimated volume using a custom code of the image analysis software to estimate the progression of the NCCLs over time. The morphological characteristics of the NCCLs were also objectively divided into three groups according to the depth to height ratio (D/H ratio). Fisher's exact test and the Cochran-Armitage trend test were used for statistical analysis. RESULTS: Saucer-shaped lesions progressed mainly in height, whereas wedge-shaped lesions increased both in height and depth. Annual progression in depth and volume significantly increased as the D/H ratio increased. More than half of the NCCLs with a small D/H ratio progressed 50 µm or more in height, whereas none of them progressed more than 50 µm in depth. Annual progression in depth significantly increased as the lesion depth at baseline increased. CONCLUSIONS: Progression patterns significantly differed between NCCLs of different shapes. Most NCCLs progressed slowly in depth regardless of their shape. Moreover, NCCLs may progress through active and inactive stages.

Clinical effectiveness of direct resin composite restorations bonded using one-step or two-step self-etch adhesive systems: A three-year multicenter study.

The purpose of this multicenter clinical study was to compare the mid-term clinical effectiveness of direct resin composite restorations using one-step or two-step self-etch adhesives (1-SEAs or 2-SEAs). In total, 352 restorations of class I-V cavities and non-carious cervical lesions in vital teeth (1-SEAs; 52 cases, 2-SEAs; 300 cases) were placed at nine university hospitals and evaluated according to the modified USPHS criteria at baseline, and after 1, 2, and 3 years. The recall rates were 86.6% (1 year), 80.1% (2 years), and 62.2% (3 years). Two restorations failed due to fracture during the follow-up, and there was no significant difference in survival rates between 1-SEAs (97.6%) and 2-SEAs (99.4%). However, 2-SEAs exhibited significantly lower occurrences of discoloration, marginal discoloration, fracture, and plaque retention. Moreover, the subjects reported a significantly lower postoperative hypersensitivity and higher overall satisfaction at all evaluation periods if 2-SEAs were used.

Evidence-based consensus for treating incipient enamel caries in adults by non-invasive methods: recommendations by GRADE guideline.

Remineralization treatment, which offers the advantage of being non-invasive, is increasingly being used as a minimal intervention treatment in managing incipient enamel caries. The aim of this review was to develop EBM guideline for optimized strategies for non-invasive treatment of incipient enamel caries. Japanese Society of Conservative Dentistry (JSCD) guideline committee formulated a Guideline for treating incipient enamel caries using the GRADE system, which is the global, mainstream standard for guideline development. The committee selected the most frequent clinical questions (CQs) in treating incipient enamel caries and identified clinically important outcomes in evaluating the efficacy of treatments. Using extensive electronic and manual searches, relevant randomized controlled trials and controlled clinical trials were identified. Based on evidence profiles produced by the committee, the panel discussed the effects, benefits and disadvantages of the selected treatments, as well as their cost effectiveness and feasibility, in order to achieve a consensus in treating incipient enamel caries non-invasively. A recommendation was made for each clinical question after voting by the panel members. Based on the evidence profile and panel discussions for each CQ, the experts strongly recommended application of topical fluoride to inhibit cavitation of incipient enamel caries, and to diminish white spot lesions.

A pilot study to assess the morphology and progression of non-carious cervical lesions.

OBJECTIVE: This longitudinal pilot study aimed to morphologically and quantitatively investigate the progress of non-carious cervical lesions (NCCLs) by using swept-source optical coherence tomography (SS-OCT). METHODS: The samples examined comprised sets of NCCL epoxy resin replicas obtained from 10 lesions in 6 patients who attended annual dental visits over 4 or 5 years. SS-OCT images of the replicas were analyzed in terms of the maximum depth (Dmax) and corresponding vertical width (VW) - using an image analyzer to estimate progression of the NCCLs over time. RESULTS: It was found that differences between wedge- and saucer-shaped lesions were morphologically distinguished well by the OCT images. There were significant differences in dimensions among Dmax, VW and horizontal width (HW). HW was the largest and Dmax was the smallest. Although no significant differences in absolute values of annual progression rates were found among Dmax, VW and HW, the percentage increase in Dmax was significantly greater compared to VW and HW. The ratios of Dmax to corresponding VW ranged from 0.49 to 1.01 for the wedge-shaped lesions and from 0.13 to 0.44 for saucer-shaped lesions, respectively. CONCLUSIONS: The dimensional analysis demonstrated notable progression with large variations. The wedge-shaped lesions appeared to show greater Dmax values compared to the saucer-shaped lesions. CLINICAL SIGNIFICANCE: With respect to the depth, the wedge-shaped lesions may progress at a greater rate compared to the saucer-shaped lesions.

Boron Accelerates Cultured Osteoblastic Cell Activity through Calcium Flux.

A low concentration of boron (B) accelerates the proliferation and differentiation of mammalian osteoblasts. The aim of this study was to investigate the effects of 0.1 mM of B on the membrane function of osteoblastic cells in vitro. Genes involved in cell activity were investigated using gene expression microarray analyses. The Ca2+ influx and efflux were evaluated to demonstrate the activation of L-type Ca2+ channel for the Ca2+ influx, and that of Na+/K+-ATPase for the Ca2+ efflux. A real-time PCR analysis revealed that the messenger RNA (mRNA) expression of four mineralization-related genes was clearly increased after 3 days of culture with a B-supplemented culture medium. Using microarray analyses, five genes involved in cell proliferation and differentiation were upregulated compared to the control group. Regarding the Ca2+ influx, in the nifedipine-pretreated group, the relative fluorescence intensity for 1 min after adding B solution did not increase compared with that for 1 min before addition. In the control group, the relative fluorescence intensity was significantly increased compared with the experimental group (P < 0.05). Regarding the Ca2+ efflux, in the experimental group cultured in 0.1 mM of B-supplemented medium, the relative fluorescence intensity for 10 min after ouabain treatment revealed a significantly lower slope value compared with the control group (P < 0.01). This is the first study to demonstrate the acceleration of Ca2+ flux by B supplementation in osteoblastic cells. Cell membrane stability is related to the mechanism by which a very low concentration of B promotes the proliferation and differentiation of mammalian osteoblastic cells in vitro.

Challenges to the clinical placement and evaluation of adhesively-bonded, cervical composite restorations.

OBJECTIVES: The incidence of non-carious cervical lesions (NCCLs) has been increasing. The clinical performance of resin composites in NCCLS was previously unsatisfactory due to their non-retentive forms and margins lying on dentin. In order to address this problem, a lot of effort has been put into developing new dentin adhesives and restorative techniques. This article discusses these challenges and the criteria used for evaluating clinical performance as they relate to clinical studies, especially long-term clinical trials. Polymerization contraction, thermal changes and occlusal forces generate debonding stresses at adhesive interfaces. METHODS: In laboratory studies, we have investigated how these stresses can be relieved by various restorative techniques and how bond strength and durability can be enhanced. Lesion forms, restorative techniques, adhesives (adhesive strategies, bond strengths, bond durability, and the relationship between enamel and dentin bond strengths) were found to have a complex relationship with microleakage. With regard to some restorative techniques, only several short-term clinical studies were available. RESULTS: Although in laboratory tests marginal sealing improved with a low-viscosity resin liner, an enamel bevel or prior enamel etching with phosphoric acid, clinical studies failed to detect significant effects associated with these techniques. Long-term clinical trials demonstrated that adhesive bonds continuously degraded in various ways, regardless of the adhesion strategy used. SIGNIFICANCE: Early loss of restoration may no longer be the main clinical problem when reliable adhesives are properly used. Marginal discoloration increased over time and may become a more prominent reason for repair or replacement. Reliable and standardized criteria for the clinical evaluation of marginal discoloration should be established as soon as possible and they should be based on evidence and a policy of minimal intervention.

Factors associated with the longevity of resin composite restorations.

This study investigated factors associated with the longevity of resin composite restorations, which were placed in 97 patients (mean age of 58 years) by 24 dentists in Nagasaki University Hospital between 1995 and 2005. All patients were under the charge of the principal investigator (SK) and most of them had been regularly checked up for up to 11 years. A total of 503 resin composite restorations (433 by SK and 70 by the other dentists) were analyzed by the Kaplan-Meier and the Cox proportional hazards model. Ten-year survival rates were 84.2% for SK and 71.8% for the others, showing a significant difference. Although the retreatment risk had a great influence on the survival time, gender and age at placement did not have. There were no significant differences in survival between conventional 2-step etch-and-rinse, 2-step self-etch adhesives with and without prior enamel etching. Cavity type had a significant influence, whereas tooth type had no effect.

Three-year clinical evaluation of a flowable and a hybrid resin composite in non-carious cervical lesions.

OBJECTIVES: This randomized controlled clinical trial evaluated the 3-year clinical performance of a hybrid (Clearfil AP-X; AP) and a flowable (Clearfil Flow FX; FX) resin composite in 98 non-carious cervical lesions. METHODS: Twenty-two patients, 11 males and 11 females (mean age: 61.9 years, range: 29-78 years) regularly visiting the Nagasaki University Hospital, participated in the study. Each patient received both materials randomly. All restorations (48 restorations for AP and 50 restorations for FX) were placed in conjunction with an all-in-one system (Clearfil S(3) Bond) by one dentist. The restorations were blindly evaluated by two examiners at baseline, 6 months, 1, 2 and 3 years using modified USPHS criteria. The data were statistically analyzed using the Cochran's Q-test and Fisher's exact test. RESULTS: All the patients were examined at each recall. However, five restorations could not be evaluated at 3-year recall as two teeth had been extracted and three restorations had been lost. The only minor problem was the integrity of the enamel margin. The incidence and extent of marginal staining increased with time, but it was still superficial. Marginal staining occurred adjacent to 11 restorations for AP and 12 restorations for FX after 3 years. Neither lesion size nor depth had influence on marginal staining adjacent to each type of resin composite. There were no significant differences in the clinical performances between AP and FX for each variable. CONCLUSIONS: Under the protocol used in this study, both types of resin composite in conjunction with S(3) Bond demonstrated an acceptable clinical performance up to 3 years.

Two-year clinical evaluation of one-step self-etch systems in non-carious cervical lesions.

OBJECTIVES: This randomized controlled clinical trial evaluated the 2-year clinical performance of S3 Bond (S3) and G-Bond (GB) in 108 non-carious cervical lesions. METHODS: Twenty-three patients, 12 male and 11 female (mean age: 61.8 years, range: 30-79 years) regularly visiting the Nagasaki University Hospital of Medicine and Dentistry, participated in the study. Each patient received both materials randomly. All restorations (53 restorations for S3 and 55 restorations for GB) were placed by one dentist. The restorations were blindly evaluated by two examiners at baseline, 6 months, 1 and 2 years using modified USPHS criteria. The data were statistically analyzed using the Cochran Q test and Fisher's exact test. RESULTS: One restoration of each material was lost during 2 years. The only minor clinical problem was the integrity of the enamel margin. Slight marginal staining occurred adjacent to 11 restorations of both S3 and GB. There was no significant difference in the clinical performance between S3 and GB for each variable. CONCLUSIONS: Under the protocol used in this study, S3 and GB have demonstrated an acceptable clinical performance up to 2 years.

Effect of a caries-detecting solution on the tensile bond strength of four dentin adhesive systems.

This study investigated the effect of a caries-detecting solution on the tensile bond strength (TBS) to sound bovine dentin--which was either rinsed thoroughly of or contaminated with the caries-detecting solution. Caries Detector (1.0% acid red in propylene glycol) was applied on flat dentin surfaces for 10 seconds, rinsed, and dried with syringe air. In another group, Caries Detector was not rinsed but air-dried. Then, the surfaces were treated with one of the following adhesive systems: Clearfil Protect Bond, Clearfil SE Bond, One-Up Bond F, or Single Bond. Furthermore, an ingredient of Caries Detector, either 1.0% acid red aqueous solution or propylene glycol, was applied to evaluate the effect of each component. In the control groups, Caries Detector was not applied to the dentin surfaces. Finally, a resin composite was light-cured and the TBS measured. Fractured specimens and treated dentin surfaces were observed by SEM. Caries Detector did not reduce the tensile bond strength of any adhesive system (p>0.05) when rinsed thoroughly. On the other hand, when dentin surface was contaminated with Caries Detector, TBS decreased significantly with Clearfil SE Bond and Single Bond. As for the ingredients of Caries Detector, the effect of acid red on TBS was not significant, but that of propylene glycol was significant.

Five-year clinical evaluation of two adhesive systems in non-carious cervical lesions.

OBJECTIVE: This controlled clinical trial evaluated the 5-year clinical performance of a self-etching primer system including selective enamel-etching with phosphoric acid and a one-bottle adhesive system. METHODS: Seventy-two non-carious cervical lesions in 8 patients (4 male and 4 female) with a mean age of 61.3 years (range 45-78) participated in the study. An enamel bevel was placed and dentin lightly ground, and cavities restored with clearfil liner bond II (LB) or single bond (SB) in conjunction with a hybrid resin composite (Clearfil AP-X). In the case of 27 cavities for LB, the enamel was pretreated with 37% phosphoric acid for 10 s. Each patient received both types of restoration, which were distributed on a random basis. All restorations (37 restorations for LB and 35 restorations for SB) were placed by one dentist. The restorations were evaluated blind after 5 years using modified USPHS criteria. The data were statistically analyzed using the Fisher's exact test. RESULTS: All but one restoration (which was replaced by a crown after the 2-year recall) were evaluated after 5 years. 100% retention rates were recorded for both restorative groups. No caries was detected in association with any restorations. The only minor problem was marginal discoloration; superficial and localized marginal discoloration occurred around 18% of the restorations, and mainly at the dentin margin. There were no significant differences in the marginal integrity between the LB and SB groups. CONCLUSIONS: Restorative materials used in this study demonstrated a good clinical effectiveness in the restoration of non-carious cervical lesions for 5 years.

Microleakage of cervical cavities restored with flowable composites.

PURPOSE: To investigate the microleakage of cervical cavities restored with flowable composites in conjunction with an all-in-one adhesive system (AQ Bond) and an experimental two-step self-etching primer system (ABF) after thermocycling or flexural load cycling. METHODS: 180 wedge-shaped cervical cavities on the labial surfaces of bovine incisors were treated with AQ Bond or ABF according to the manufacturers' instructions. The treated cavities were filled with one of three flowable composites (AElite Flo, Metafil Flo or Protect Liner F). Ten of 30 specimens for each group were immersed in 0.5% basic fuchsin solution immediately after finishing of the restorations. Specimens to be subjected to thermocycling (5-60 degrees C, 15 seconds dwell time, 5000 cycles) or to flexural load cycling (approximately 0.5 mm labio-lingual displacement at the incisal edge, 10,000 cycles, 1 Hz) prior to immersion in the dye were also prepared. After 24-hour storage in the dye solution, the teeth were sectioned longitudinally through the center of the restorations, and the degrees of dye penetration scored. The microleakage scores of a hybrid composite (Clearfil AP-X) obtained from our previous study were used for comparison. The data were analyzed with the Kruskal-Wallis test and the Mann-Whitney U-test (P < 0.05). RESULTS: No significant differences in the microleakage patterns and scores were found among the flowable composites. On the other hand, significant differences in the microleakage patterns and scores were observed between the flowable and the hybrid composites. Thermocycling caused deterioration of marginal integrity, and the flowable composites showed more microleakage than the hybrid composite. In contrast, flexural load cycling did not cause deterioration of the marginal integrity when the cavities were filled with the flowable composites. Statistical analysis also revealed that the adhesive systems played a large role in the microleakage patterns.

The effect of light-curing modes on the microleakage of cervical resin composite restorations.

OBJECTIVE: This study investigated the effect of light-curing modes on the microleakage of cervical resin composite restorations. METHODS: Eighty wedge-shaped cervical cavities, C-factor approximately 1.3, were prepared on the labial surface of bovine incisors. The cavities were treated with a two-step experimental self-etching primer adhesive system containing an antibacterial monomer (ABF), according to the manufacturer's instructions, and filled with a single increment of a hybrid resin composite. The restorations were allocated randomly into four groups of 20: Group 1-the restorations were light-cured for 40 s with a conventional light-curing unit (New Light VL-II); Group 2-the restorations were cured with Candelux using a two-step mode; Group 3-the restorations were cured with Astralis 7 using a ramping mode; Group 4-the restorations were light-cured for 3 s with a plasma arc light-curing unit (Wave Light). Half of the specimens from each group were subjected to thermocycling (5-60 degrees C, 15 s dwell time, 5000 cycles) prior to immersion in 0.5% basic fuchsin. The teeth were sectioned and the degrees of dye penetration were scored. The data were analyzed with either the Kruskal-Wallis test or the Mann-Whitney U-test (p < 0.05) RESULTS: No significant differences were found in the microleakage scores among the light-curing modes used. The restorations tended to display more microleakage when they were subjected to thermocycling, but the differences were not statistically significant. CONCLUSIONS: These findings suggest that light-curing modes may have no effect on the microleakage of cervical cavities with a small C-factor, as is the case in this study.

Nanoleakage of dentin adhesive systems bonded to Carisolv-treated dentin.

The hybrid layer created in caries-affected dentin has not been fully elucidated and may influence bond durability. This study investigated the nanoleakage patterns of caries-affected dentin after excavation with Carisolv or conventional instruments treated with one of three adhesive systems. Flat occlusal dentin surfaces, including carious lesions, were prepared from extracted human molars and finished with wet 600-grit silicon carbide paper. Carious dentin was removed with Carisolv or round steel burs in conjunction with Caries Detector. PermaQuik, Single Bond or One-Up Bond F was bonded to the excavated dentin surfaces and adjacent flat occlusal surfaces and it was covered with Silux Plus resin-based composite. After 24-hour storage in 37 degrees C water, the bonded interfaces were polished to remove flash, and the surrounding tooth surfaces were coated with nail varnish. Specimens were immersed in 50% (w/v) silver nitrate solution for 24 hours, exposed to photo developing solution for eight hours, then sectioned longitudinally through the bonded, excavated dentin or "normal" dentin surfaces. The sectioned surfaces were polished, carbon coated and observed in a Field Emission-SEM using back scattered electrons. Silver deposition occurred along the base of the hybrid layer for all specimens. However, Single Bond showed a greater density of silver deposition in the caries-affected dentin compared with normal dentin. PermaQuik had a thicker hybrid layer in caries-affected dentin than normal dentin. One-Up Bond F exhibited a thin hybrid layer in normal dentin, but the hybrid layer was often difficult to detect in caries-affected dentin.