A cross‐sectional study: non‐carious cervical lesions,cervical dentine hypersensitivity and related risk factors

The present survey aims to study the prevalence and clinical characteristics of non‐carious cervical lesions (NCCLs) and cervical dentine hypersensitivity (CDH), as well as their possible risk factors in a general population in China. A total of 1023 subjects were included in the present study. Each subject completed a structured interview, and all teeth of each subject were examined by a practitioner to determine NCCLs and CDH. Teeth with NCCLs and CDH were diagnosed according to the tooth wear index and by a blast of air from a triple syringe, respectively. Binary logistic regression was completed by analysing the association of risk factors with the occurrence of NCCLs and CDH. Loss of attachment (LOA) and gingival recession (GR) of teeth with NCCLs and/or CDH were measured using Williams periodontal probe. The diagnoses of NCCLs and CDH established following a clinical assessment yielded an overall prevalence of 61·7% and 27·1%, respectively. The 60–69 age group had the greatest proportion of subjects with NCCLs or CDH. The pre‐molars were the most commonly affected teeth type with NCCLs or CDH. The proportion of teeth with CDH associated with NCCLs increased significantly with age, but the proportion of teeth with CDH only associated with LOA or GR decreased slowly with age. The single variables and interactive effects of variables associated with the occurrence of NCCLs include the following: age group, occupation type, method of toothbrushing, frequency and method of toothbrushing, and method of toothbrushing and duration of a toothbrush used. Gender, age group, occupation type and frequency of toothbrushing were associated with the occurrence of CDH. The current study presented higher prevalence of NCCLs and CDH in a general Chinese population. Both diseases were closely associated with age and periodontal status. The portion of the population with NCCLs or CDH had different risk factors.     

Clinical features and factors associated with non‐carious cervical lesions and dentin hypersensitivity

Determining the factors associated with NCCLs and DH in populations could guide the implementation of specific preventive measures. This study evaluated the clinical features and factors associated with non‐carious cervical lesions (NCCLs) and dentin hypersensitivity (DH) in a Brazilian population. The participants were 118 patients at the Dentistry Clinic of our dental school. They completed an interview to obtain personal information and determine the possible factors associated with NCCLs and DH. Clinical examination was undertaken to record the NCCLs, shape of the lesion and certain occlusal factors. DH was diagnosed by air and probe tests. Data were analysed with the multilevel Poisson regression and prevalence ratios, and the respective 95% confidence intervals were calculated. The prevalence of NCCLs and DH among patients was 67·8% and 51·7%, respectively. Of a total number of 2902 teeth examined, 9·65% had NCCLs and 5·82% were sensitive to air. The most affected teeth for both conditions were the premolars. Most of the NCCLs were wedge‐shaped and located in the maxilla. The factors associated with NCCLs and DH were age and presence of premature occlusal contacts. NCCLs were also significantly associated with consumption of wine and alcoholic beverages, and DH with consumption of acidic fruits and juices. NCCLs were a common finding, with higher frequency in more advanced age groups, the maxilla and premolars. A significant association occurred between NCCLs, premature contacts and consumption of wine and alcoholic beverages. DH was associated with NCCLs, premature contacts and with the consumption of acidic fruits and juices.     

Non‐carious cervical lesions (NCCLs) in a random sampling community population and the association of NCCLs with occlusive wear

This study investigated the prevalence, risk factors and association of occlusive wear with non‐carious cervical lesions (NCCLs) in the general Chinese population. A total of 1320 subjects were recruited, and multistage and random sampling methods of survey spots were performed. All age groups comprised similar numbers of participants and equal numbers of males and females. Each subject completed a structured interview, and all teeth of each subject were examined by a practitioner to determine NCCLs and occlusive wear. Binary logistic regression was conducted by analysing the association of risk factors with the occurrence of NCCLs. Bivariate correlation analysis was performed by determining the association of NCCLs dimension or depth with the range of occlusive wear facets. Clinical assessment showed that the overall prevalence of subjects diagnosed with NCCLs was 63%. The proportion of subjects or teeth with NCCLs significantly increased with age. Pre‐molars were the most commonly affected teeth. Single variables and interactive effects of variables associated with the occurrence of NCCLs include the following: age group, intensity of toothbrushing, frequency of fresh fruit consumption and interactive effect between intensity of toothbrushing and frequency of fresh fruit consumption. A weak positive correlation of the grading index was found between NCCLs dimension, size or depth and range of occlusive wear facets. This study reported the higher prevalence of NCCLs in the general Chinese population. Implementation of a combined strategy to reduce risk factors of NCCLs could be more effective than individual techniques; meanwhile, the occurrence of NCCL could be related to the wear degree of occlusive defects in the population studied.     

Clinical investigation of G‐Bond resin‐based adhesive to non‐carious cervical lesions over five years

Background: The aim of this study was to evaluate the clinical performance of G‐Bond all‐in‐one adhesive with Gradia Direct resin composite placed in non‐carious cervical lesions (NCCLs) over a five‐year period. Methods: Forty‐seven restorations were placed in NCCLs in 10 subjects (age 45–75 years) after written informed consent was obtained. Institutional ethical approval for the trial was obtained before recruitment. Restorations were placed according to the manufacturer’s instructions and using 50% phosphoric acid to etch uncut enamel margins. Patients were recalled annually for five years and restorations reviewed for presence and marginal staining. Photographic records were obtained prior to restoration, immediately after placement and at each recall. Results: At five years, 6 of the original 10 subjects were available for recall, meaning 27 restoration sites could be evaluated. All restorations remained intact apart for one partial failure at four years. This resulted in a cumulative retention rate of 97.5% of restorations at five years. Marginal staining occurred around seven restorations during the study. Staining tended to be isolated to a few patients. Conclusions: It was concluded that G‐Bond with Gradia Direct resin composite showed excellent results over the five years of the study. This material combination seems very suitable for the restoration of NCCLs.     

Clinical evaluation of non-carious cervical lesion restorations using a HEMA-free adhesive: three-year results

Background: The use of all‐in‐one resin‐based adhesives in clinical practice has continued to increase. The aim of this study was to evaluate retention and marginal staining of a HEMA‐free all‐in‐one adhesive Go! (SDI, Australia) and Ice resin composite in non‐carious cervical lesions (NCCLs). Methods: Forty‐one restorations were placed in 13 patients (age range 44–72 years). Human Ethics Committee approval from the University of Melbourne and Dental Health Services Victoria was obtained. Restorations were bonded and placed according to the manufacturer’s instructions. Enamel etching was performed on NCCL margins after cleaning with pumice and water. Patients were recalled at six months and one, two and three years. Restorations were evaluated for retention and marginal staining, and photographic records of restorations were obtained. Results: At three years, six patients were available for recall with 23 restoration sites reviewed. At the six‐month recall, three restorations had been lost, with a further two lost at two years. At three years, an overall cumulative retention rate of 85% was calculated using survival analysis. Fifteen of the 23 restorations showed slight marginal staining. Conclusions: At three years, the overall retention rate of 85% indicates a satisfactory result for this new adhesive. Marginal staining was regarded as minimal.     

Clinical evaluation of a polyacid-modified resin composite (Dyract) in class V carious lesions: 5-year results

This study evaluated the 5-year clinical performance of polyacid-modified resin composite, Dyract (DeTrey/Dentsply, Konstanz, Germany), restorations in class V carious lesions. Ninety-two class V carious lesions in 28 patients were restored with Dyract. Restorations were clinically evaluated at baseline, 1-, 2-, 3-, 4-, and 5-year recalls and were evaluated according to the modified Ryge criteria by two experienced calibrated examiners in regard to color match, marginal discoloration, wear or loss of anatomical form, caries, marginal adaptation, and surface texture. The retention rate after 5 years compared to baseline in class V carious restorations was 84%, with only 12 restorations failing. Color change and marginal discoloration in restorations were found to be statistically significant (p = 0.0238 and p < 0.0001, respectively) at the end of the 5 years, but did not require replacement of any of the restorations. The results of this study revealed that at the end of 5 years, Dyract exhibited a clinically acceptable success rate but had significant color changes and marginal discoloration in class V carious lesions.     

Effect of root morphology on biomechanical behaviour of premolars associated with abfraction lesions and different loading types

The aim of this study was to investigate the biomechanical behaviour of maxillary premolar teeth regarding root morphology and abfraction depth, submitted to axial and oblique occlusal load. The investigation was conducted using 3D finite element analysis and strain gauge test. Sound maxillary premolar single and double root were selected for 3D model generation. The teeth were scanned for external morphology data acquisition. The 3D geometry was stored in *.STL and exported to Bio‐CAD software (Rhinoceros‐3D) to model generation. Mesh generation, mechanical properties and boundary conditions were performed in finite element software (Femap, Noran Engineering, USA). Twelve models were generated: sound tooth, 1·25 and 2·5 mm abfraction teeth. 100N compressive static load was applied: axially and 45° angle to the long axis on the palatine surface of the buccal cusp. Two strain gauges were bonded on the teeth mounted in a mechanical testing machine. Von Mises criterion showed that the double‐root teeth associated with 2·5 mm abfraction and oblique loading presented higher stress values. Axial loading associated with single‐root teeth propitiated the lowest stress rates. Double root sound 1·25 and 2·5 mm abfraction teeth associated with oblique loading showed the highest strain values (μS): 692·6, 1043·31 and 1236·14, respectively. Single root sound 1·25 and 2·5 mm abfraction teeth associated with oblique loading showed 467·10, 401·51 and 420·98 strain values, respectively. Axial loading showed lower strain rates, ranging from 136·12 to 366·91. The association of deep lesions, oblique loading and double‐root tooth promoted higher stress and strain concentration.     

Longevity of a resin-modified glass ionomer cement and a polyacid-modified resin composite restoring non-carious cervical lesions in a general dental practice

BACKGROUND: Long-term prospective survival studies of resin-modified glass ionomer cements (RMGICs) and polyacid-modified resin composites (compomers) placed in non-carious cervical lesions (NCCLs) are lacking from general dental practice. Short-term studies have shown an unsatisfactory clinical performance for several materials. METHODS: One practitioner placed 87 compomer (Compoglass, Vivadent-Ivoclar) and 73 encapsulated RMGIC (Fuji II LC, GC Int.) restorations in NCCLs for 61 adults. Compoglass was placed using SCA primer, and Fuji II LC using GC Dentin Conditioner. No cavity preparation was undertaken. The Kaplan-Meier method was used for estimating the cumulative survivals for those restorations that were replaced, with the probability level set at alpha = 0.05 for statistical significance. RESULTS: Restorations were judged unsatisfactory (by the practitioner and the subjects) because of surface and marginal loss of material (68.8 per cent), dislodgement (18.8 per cent) and discoloration (12.4 per cent), these modes being similar for both materials (P = 0.35). Unsatisfactory restorations were replaced in 121 (75.6 per cent) instances. After periods of up to five years, cumulative survival estimates were 14.9 (5.8 Standard Error) per cent for Compoglass and zero per cent for Fuji II LC (P = 0.74). Median survivals were 30 months for Compoglass and 42 months for Fuji II LC. CONCLUSION: Both materials had high long-term unsatisfactory performances when placed in non-prepared NCCLs in a general dental practice.     

上颌前磨牙非龋性颈部缺损修复的有限元研究

目的:探讨充填治疗非龋性颈部缺损时,洞型设计、窝洞深度及充填材料和咬合调整因素的影响。方法:构建成人上颌第一前磨牙三维有限元模型,其颊侧颈部有不同洞型(楔形、矩形和弧形)和窝洞深度(0.5mm、1.0mm和1.5mm),模拟用玻璃离子黏固剂(GIC)、复合树脂和银汞合金充填,计算模型在正常的侧向、垂直向加载及创伤的侧向、垂直向加载时,应力值和应力分布。结果:正常颊侧颈部主要为拉应力,近根尖向出现压应力,应力分布较均匀;创伤时主要也为拉应力但应力集中,且较正常产生更大的应力。2种咬合状态在侧向加载都比垂直向产生更大应力和加重应力集中。不同窝洞深度间应力差异小,但有深度加深、应力变大的正相关性。深度0.5mm、1.0mm的楔形、弧形和矩形洞型差异小。但在1.5mm时,矩形洞型产生的应力远大于楔形(约4倍),楔形洞型应力略大于弧形(0.8～4.1MPa)。相同条件下,银汞合金充填体界面应力值大于GIC和复合树脂(3～9倍),GIC小于复合树脂(0.2～2.4MPa)。结论:窝洞较浅时,洞型不是影响治疗的首要因素,窝洞较深则应避免矩形洞型。     

上颌全口义齿(牙合)面形态对基托应力分布的影响

目的:探讨异常牙合面形态对上颌全口义齿基托应力分布状况的影响。方法:建立正常形态、舌尖磨耗及颊尖磨耗三类不同牙合面形态的上颌全口义齿及其支持组织的三维有限元模型,在全牙列加载下分析基托内应力分布状况。结果:Ⅰ类模型(正常牙合面形态),基托呈现前牙区和后牙区应力均衡分布趋势;Ⅱ类模型(舌尖磨耗)整个中线区均为高应力值区,随牙尖斜度增大,中线区集中趋势愈加明显;Ⅲ类模型(颊尖磨耗),始终呈现基托前部应力集中。结论:异常的牙合面形态可能对上颌全口义齿基托的应力分布状况有明显的影响作用。提示临床行上颌单颌全口义齿修复时,应考虑患者对颌天然牙列的牙合面磨耗形态,必要时先进行下颌牙列异常牙合面形态的调整后再行上颌总义齿的修复。     

Effects of post materials and length on the stress distribution of endodontically treated maxillary central incisors: a 3D finite element analysis

Summary  Traditionally, using a long post can cause progressive removal of the root structure, complicate the ability to re-treat the tooth if necessary and make it difficult to apply an adhesive bonding agent into the root canal. It is unclear if a shorter post length can be applied when a light translucent glass fibre post and adhesive resin cement are used. The aim of this study was to evaluate the biomechanical performance of endodontically treated teeth restored with three post materials, glass-fibre, stainless steel and cast-nickel chromium posts and cores of different lengths of 7, 10 and 13 mm. A 3D finite element analysis model of the maxillary central incisor was constructed. An occlusal load of 300 N was applied to a node at the palatal surface of the crown at 45° to the long axis of the tooth. von Mises stress analyses were carried out in three regions. Simulated data were collected for plotting various pattern graphics and conducting statistical tests. The pattern graphics showed that when the post length changed from 13 to 7 mm, the stress patterns were even and flat in all fibre-post groups, while the stress patterns of the metal-post groups showed an M-shaped peak and trough. Statistical tests showed that the shorter fibre post was superior to the longer metal post in some situations. Within the limitations of this study, it was concluded that when a metal post is used, the post should be as long as possible, while the biomechanical performance of a glass-fibre post combined with a composite resin core was less sensitive to post length.