Occlusal tooth wear in Chinese adults with shortened dental arches

To assess associations between occlusal tooth wear and shortened dental arches (SDA) in Chinese 40 years and older subjects. From a sample of 1462 urban and rural adults, those presenting with SDA (n = 150) were compared with a control group of 65 randomly selected subjects with complete dentitions (CDA). Occlusal wear was assessed using a modified Smith and Knight index – the occlusal tooth wear index (OWTI) – and analysed using multivariate (logistic) regression. There was no significant effect from SDA on severe occlusal wear (OTWI score 3 or 4: OR = 2·016; 95% CI = 0·960–4·231; P = 0·064). Higher age was associated with severe occlusal wear (P values ≤0·007) and with higher mean OTWI scores; urban had less often severe occlusal wear than rural residents (OR = 0·519; P = 0·008). Higher mean OTWI scores were associated with rural residents, except for anterior teeth. Females had lower mean OTWI score for anterior teeth (effect = ?0·153; P = 0·030). Premolars in SDA had higher mean OTWI scores compared with those in CDA (effect = +0·213; P = 0·006). In SDA, more posterior occluding pairs (POPs) were associated with lower mean OTWI sores for anterior teeth (effect: ?0·158; P = 0·008) and higher scores for molars (effect: +0·249, P = 0·003). Subjects with SDA or CDA presented comparable occlusal wear, but premolars in SDA tend to have higher probability for having occlusal wear. Fewer numbers of POPs were associated with more wear in anterior teeth.     

Assessment of the amount of tooth wear on dental casts and intra‐oral photographs

Tooth wear is a multifactorial condition, leading to the loss of dental hard tissues. Many grading scales are available to assess the amount of tooth wear, one of which is the tooth wear evaluation system (TWES). A grading scale can be used chairside, on casts and on photographs. The aim was to test whether the grading scales of the TWES, used on casts and on photographs, resulted in comparable scores. In addition, it was tested whether these scales can be used to assess tooth wear reliably on photographs. Of 75 tooth wear patients, sets of casts and series of photographs were obtained and graded. Comparison of the grading on casts and on photographs revealed equal median values and percentiles for both occlusal/incisal grading and non‐occlusal/non‐incisal grading. The grading on casts and on photographs showed a high correlation for the occlusal/incisal grading and a low correlation for the non‐occlusal/non‐incisal grading (Spearman's rho = 0·74 and rho = 0·47; P < 0·001). Concerning the grading on photographs, the interexaminer reliability was fair‐to‐good (ICC = 0·41 to ICC = 0·55) while the intra‐examiner reliability was fair‐to‐good to excellent (ICC = 0·68 to ICC = 0·86) for the occlusal/incisal grading. For the non‐occlusal/non‐incisal grading, the interexaminer reliability was poor to fair‐to‐good (ICC = 0·22 to ICC = 0·59), while the intra‐examiner reliability was fair‐to‐good to excellent (ICC = 0·64 to ICC = 0·82). It was concluded that the scores obtained with the grading scales of the TWES on casts and on photographs are comparable. The grading scales can be used in a reliable way on photographs, which is especially the case for occlusal/incisal grading.     

Assessment of occlusion after placement of stainless steel crowns in children – a pilot study

Many stainless steel crowns (SSCs) disrupt the occlusion in children, but stabilisation appears to occur within a short period post‐placement. The extent and mechanism of these short‐term occlusal changes in children are unknown. This study sought to determine whether placement of a SSC changes the maximum intercuspation position (MIP) in children, whether the MIP returns to normal within 4 weeks and whether local anaesthesia had an effect on the child's ability to achieve MIP. The T‐Scan^® III was used for the measurement of occlusal contacts. Reliability and reproducibility of the system was determined using a calibration exercise where MIP recordings were taken of eleven children not undergoing any dental treatment. For the main study, the percentage of total occlusal force on each tooth was recorded in 20 children preoperatively, after local anaesthesia, after SSC placement and 4 weeks postoperatively. There was no significant difference in MIP (P = 0·435) preoperatively and post‐administration of local anaesthesia. There was a significant difference between the preoperative force on a tooth and the reading after crown placement (P = 0·0013, Wilcoxon test). By 4 weeks, there was no significant difference overall between post‐SSC placement and the preoperative value for the tooth (P = 0·3). Administration of local anaesthesia did not affect the ability of a child to attain MIP. Maximum intercuspation position was disturbed by the placement of a SSC in seven of 20 cases. When MIP was disturbed, in most cases, it returned to preoperative status within 4 weeks of crown placement.     

Assessment of the progression of tooth wear on dental casts

Many methods are available for the grading of tooth wear, but their ability to assess the progression of wear over time has not been studied frequently. The aim was to assess whether the occlusal/incisal grading scale of the Tooth Wear Evaluation System (TWES) was sensitive enough for the detection of tooth wear progression from 14 to 23 years of age. A total of 120 sets of dental casts were gathered from 40 people, of whom impressions were made at 14, 18 and 23 years. The TWES was used to assess loss of clinical crown height throughout the entire dentition. There was a significant difference in the TWES scores between the three age groups on all teeth (Friedman tests; P < 0·005 in all cases). Post hoc Wilcoxon tests revealed that the difference between the scores between 14 and 18 years and between 18 and 23 was significant for most teeth. It was concluded that the TWES is sensitive enough to detect changes in tooth wear over time.     

Estimation of the rate of tooth wear in permanent incisors: a cross‐sectional digital radiographic study

This study used conventional digital radiography to estimate the rate of tooth wear (TW) of maxillary and mandibular central incisors based on a cross‐sectional study design. The crown length of 1239 permanent maxillary and mandibular central incisors from 346 persons (age groups: 10, 25, 40, 55 and 70 years ±3) were measured by three calibrated dentists. Study teeth were intact incisally, had clearly visible incisal edges and cementoenamel junctions and had natural tooth antagonists. Measures were based on digital radiographic images (N = 666) archived in MiPACS within the electronic health record (axiUm^®) from the College of Dentistry patient database. Incisor crown length decreased at a linear rate in both arches over the 60 years represented by the age groups. The average crown length for maxillary incisors in the youngest age group was 11·94 mm, which decreased by an average of 1·01 mm by median age 70. For mandibular incisors, the average crown length in the youngest age group was 9·58 mm, which decreased by an average of 1·46 mm in the oldest age group. Males and females showed similar rates of TW. Regardless of age, females demonstrated smaller mean crown height for maxillary incisors than males (P < 0·0001). Measures by the examiners demonstrated good agreement, with an interclass correlation coefficient of 0·869 and an average intra‐examiner correlation of 99·5%, based on repeated measurements (n = 100). TW was estimated to average 1·01 mm for maxillary central incisors and 1·46 mm for mandibular central incisors by age 70 years.     

An epidemiological scoring system for tooth wear and dental erosive wear

Background: The prevalence and severity of tooth wear and dental erosion is rising in children and there is no consensus about an index to be employed. Aim: To assess the reliability of an epidemiological scoring system dental wear index (DWI) to measure tooth wear and dental erosive wear. Design: An epidemiological cross‐sectional survey was conducted to evaluate and compare tooth wear and dental erosion using the dental wear index and erosion wear index (EWI). The study was conducted with randomised samples of 2,371 children aged between 4 years and 12 years selected from the State of São Paulo, Brazil. Records were used for calculating tooth wear and dental erosion; the incisal edge and canine cusp were excluded. Results: As the schoolchildren's ages increased the severity of primary tooth wear increased in canines (P = 0.0001, OR = 0.34) and molars (P = 0.0001, OR = 2.47) and erosion wear increased in incisal/occlusal (P = 0.0001, OR = 5.18) and molars (P = 0.0001, OR = 2.47). There was an increased prevalence of wear in the permanent teeth of older schoolchildren, particularly on the incisal/occlusal surfaces (P = 0.0001, OR = 7.03). Conclusion: The prevalence of tooth wear and dental erosion increased as age increased in children. The epidemiological scoring system Dental Wear Index is able to measure both tooth wear and dental erosive wear. This index should be used to monitor the progression of non‐carious lesions and to evaluate the levels of disease in the population.     

Association between occlusal force distribution in implant overdenture prostheses and residual ridge resorption

This study aimed to investigate residual ridge resorption (RRR) of anterior and posterior maxillary and mandibular edentulous ridges, in patients treated with mandibular implant overdentures (IOD) and compare with conventional complete denture (CD) wearers, and to determine at each location, the association of RRR with the occlusal forces distribution and other patients’ variables. The anterior and posterior RRR of IOD (six males, 17 females) and CD (12 males, 11 females) groups were determined using baseline and follow‐up dental panaromic radiographs (DPT) (mean intervals 4 ± 1·8 years). The bone ratios were calculated using proportional area: anatomic to fixed reference areas and mean difference of ratios between the intervals determined RRR. The ridge locations included anterior and posterior maxillary and posterior mandibular arches. The T‐Scan III digital occlusal system was used to record anterior and posterior percentage occlusal force (%OF) distributions. There were significant differences in anterior and posterior %OF between treatment groups. Two‐way anova showed RRR was significant for arch locations (P = 0·005), treatment group (IOD versus CD) (P = 0·001), however, no significant interaction (P = 0·799). Multivariate regression analyses showed significant association between RRR and %OF at anterior maxilla (P = 0·000) and posterior mandible (P = 0·023) and for treatment groups at posterior maxilla (P = 0·033) and mandibular areas (P = 0·021). Resorption was observed in IOD compared to CD groups, with 8·5% chance of less resorption in former and 7·8% in the latter location. Depending on arch location, ridge resorption at various locations was associated with occlusal force distribution and/or treatment groups (implant prostheses or conventional complete dentures).     

Two-body and three-body wear of glass ionomer cements

Objectives. Glass ionomer cements (GIC) have been modified in an attempt to improve their mechanical properties. The objective of the present paper was to compare the two‐body and three‐body wear of four modified GIC. The tested materials were Fuji IX (GC Corporation), Hi‐Fi (Shofu) and Ketac Molar Aplicap (3M/ESPE). The cermet cement Ketac Silver Maxicap (3M/ESPE) was used as reference material. Methods. Two‐body wear tests were carried out in the computer controlled ‘artificial mouth’ of the Munich Dental School, three‐body wear was tested with the ACTA wear machine. Results. The resulting average two‐body wear rates (in µm) were: Fuji IX 327 (SD ± 82) < Ketac Molar 379 (SD ± 94) < Hi‐Fi 376 (SD ± 90) < Ketac silver 449 (SD ± 127). The differences between the materials were significant (P < 0·05, anova , modified LSD‐test) with the exception of Ketac Molar and Hi‐Fi. The average three‐body wear rates (in µm) were: Hi‐Fi 30 (SD ± 10) < Ketac Molar ± 42 (SD ± 12) < Fuji IX 49 (SD ± 14) < Ketac silver 73 (SD ± 23). The difference between Ketac silver and the three other materials was significant (P < 0·05, anova , modified LSD‐test). No significant difference was calculated between Hi‐Fi, Ketac Molar and Fuji IX. Conclusions. As Ketac Molar, Hi‐Fi and Fuji IX show better wear resistance compared to Ketac silver both in occlusal‐contact and contact‐free areas, it may be assumed that the wear resistance of a glass ionomer cement may be improved more by changing the powder : liquid ratio than by incorporating silver particles into the glass powder.     

Psychometric properties of the Dutch version of the Orofacial Esthetic Scale (OES‐NL) in dental patients with and without self‐reported tooth wear

The aim of this study was to test the psychometric properties of the Dutch version of the Orofacial Esthetic Scale (OES) in dental patients with and without self‐reported tooth wear. The English version of the OES was translated into Dutch, following established guidelines for cross‐cultural adaptation of health‐related quality of life measures. The reliability of the resulting OES‐NL was tested in a test–retest study on 343 subjects; its validity was tested with the use of convergent validity on 582 subjects. The test–retest reliability of the OES‐NL showed intra‐class correlation coefficients (ICC) that ranged from 0·76 to 0·82, which can be qualified as excellent. The Cronbach's alpha revealed that the overall internal consistency of the scale was good (α = 0·89). Convergent validity was confirmed by the association between the OES‐NL summary scores and three questions of the Dutch version of the Oral Health Impact Profile (OHIP‐NL). The calculated Spearman's rank correlation coefficients ranged from −0·43 to −0·54 and were all significant (P < 0·001). The Dutch version of the Orofacial Esthetic Scale (OES‐NL) showed good psychometric properties, making it suitable for the assessment of self‐perceived aesthetics in Dutch dental patients with and without self‐reported tooth wear.     

The effects of salivas on occlusal forces

Contacting surfaces of opposing teeth produce friction that, when altered, changes the contact force direction and/or magnitude. As friction can be influenced by several factors, including lubrication and the contacting materials, the aim of this study was to measure the occlusal load alterations experienced by teeth with the introduction of different salivas and dental restorative materials. Pairs of molar teeth were set into occlusion with a weighted maxillary tooth mounted onto a vertical sliding assembly and the mandibular tooth supported by a load cell. The load components on the mandibular tooth were measured with three opposing pairs of dental restorative materials (plastic denture, all‐ceramic and stainless steel), four (human and three artificial) salivas and 16 occlusal configurations. All lateral force component measurements were significantly different (P < 0·0001) from the dry (control) surface regardless of the crown material or occlusal configuration, while the effects of the artificial salivas compared to each other and to human saliva depended on the crown material.     

The use of likelihood ratio methodology to find predictors of treatment outcome in patients with dental injury diagnoses

Summary The purpose of this prospective, cohort study of patients with dental injuries was to develop prediction rules to predict treatment response related to the management of dental injuries. The study comprised of 130 patients with a single permanent incisor affected by a dental displacement (n = 100) or fracture injury (n = 30). Laser Doppler flowmetry (LDF) measurements of pulpal blood flow (PBF) were taken 6 and 18 weeks after dental injury Treatment response (success or failure) was categorized based on findings of clinical and radiographical evaluation after 9 months. Forty‐four (34%) subjects were categorized as treatment success (absence of loss of sensitivity, periapical radiolucency and grey discolouration of crown), 43 (33%) as treatment failures (loss of sensitivity, and periapical radiolucency and/or grey discolouration of crown) and 43 (33%) as acceptable outcome (loss of sensitivity). After using univariate analysis to determine the association between potential clinical and LDF predictor variables and treatment response status, preliminary prediction rules were developed for prediction of success [positive likelihood ratio (LR), 29·0; 95% confidence interval (CI), 1·7–496·4] and failure (negative LR, 0·55; CI, 0·4–0·7). The most important variables were subluxation, root fracture, baseline PBF level and change in PBF level at 3‐month follow‐up. Outcome following the management of dental injuries may be predicted from variables collected from LDF and physical examination. Predictive modelling may provide clinicians with the opportunity to identify ‘at‐risk’ patients early and initiate specific treatment approaches.     

Imaging temporomandibular disorders: Reliability of a novel MRI-based scoring system

The aim of this study was to assess the inter- and intrarater reliability of a recently proposed scoring system for temporomandibular disorders (TMD), based upon radiological findings from magnetic resonance imaging (MRI).Patients with clinically suspected uni- or bilateral TMD, and subsequently conducted MRI examination of both temporomandibular joints, were included in this study. MRI data were independently evaluated by two experienced radiologists according to the DLJ scoring system proposed by Wurm et al., which includes assessment of the following categories: articular disk (prefix ‘D’), direction of disk luxation (prefix ‘L’), and osseous joint alterations (prefix ‘J’).60 patients (49 female and 11 male) were eligible for analysis. No significant differences were found between both observers regarding ‘D’ and ‘L’ scores (p = 0.13 and p = 0.59, respectively). Significant differences were found for the assessment of subtle osseous changes (‘J0’ category: p = 0.041; ‘J1’ category: p = 0.018). Almost perfect intra- and interrater agreements were found for ‘D’ and ‘L’ categories (intrarater and interrater agreements for ‘D’: κ = 0.92 and κ = 0.84, respectively; intrarater and interrater agreements for ‘L’: κ = 0.93 and κ = 0.89, respectively). However, the assessment of ‘J’ categories revealed only moderate interrater agreement (κ = 0.49).The DLJ scoring system based upon MRI findings is feasible for routine clinical TMD assessment, and may help to simplify interdisciplinary communication between radiologists and clinicians.     

Expectations and final evaluation of complete dentures by patients,dentist and dental technician

Summary There is a poor association between the dentist’s evaluation of denture quality and patients’ satisfaction with their dentures. Possible differences between dental professionals and patients’ expectations might help explain differences in outcome evaluations. This study compared scores given by a dentist, a dental technician and patients for their expectations before and their final evaluation after complete dentures treatment. Twenty completely edentulous patients, a prosthodontist and a dental technician provided scores for the expected aesthetic and functional results of their dentures based on a visual analogue scale at baseline. Post‐treatment completion ratings were given after adjustments, by dentist and patients. The dental technician provided post‐treatment completion ratings after completing the dentures. The patients had higher expectations than the dental technician and the dentist perceived for both aesthetic and function (P < 0·001). The patients also presented higher post‐treatment completion ratings than the dental professionals perceived for final aesthetics (P = 0·016, Kendall’s W = 0·207) and function (P = 0·002, Kendall’s W = 0·303). Only the dentist presented a statistically significant difference between expectations (lower) and final (higher) outcomes for aesthetics (P = 0·017) and function (P = 0·003). There was no correlation between expectations and post‐treatment completion ratings according to the patients’ age. There was also no correlation between the patients’ gender and expectation scores. Patients presented higher expectations regarding their dentures than dental professionals. The dentist believed that dentures would bring fewer benefits than patients did, but his perception of denture benefits post‐treatment was significantly higher than his expectations.     

Computer simulation of the occlusal anatomy of the first mandibular molar after varying the determinants of mandibular movement in the CICERO CAD/CAM system

Static and dynamic occlusal interferences often occur in restorations. The CICERO CAD/CAM technique was used to control the occlusal dimensions of all‐ceramic restorations by setting the variables which determine the mandibular contact movements. The anatomy of the occlusal form of the (pre)molar teeth is influenced by the setting of the sagittal and transversal determinants of mandibular contact movements. In this study the variation in occlusal morphology of a high‐ and low‐limit setting of six variables was compared with an averaged setting. The settings (high, low and averaged, respectively) of the mandibular movement: the sagittal condylar (60°, 0°, 30°) and the incisal guide angle (60°, 0°, 30°) as well as the long centric articulation (1·2 mm, 0 mm, 0·6 mm) influence mainly the antero‐posterior direction, whereas the settings of Bennett movement (laterotrusion: 30°, 0°, 15°), Bennett side shift (laterotranslation: 1, 0, 0·5 mm) and the wide centric (lateral intercuspal contact area: 0·6, 0, 0·3 mm) will mainly influence the transversal direction of the mandibular movement. The influence of the variation of settings on ‘dynamic’ crown morphology as compared with the static crown morphology was studied by comparison of mesio‐distal and bucco‐lingual sections at the same occlusal position of the first lower molar design. Furthermore, the amount of material needed for the correction of the ‘static’ crown to avoid interferences in dynamic conditions was calculated. It appeared that most correction was needed for the ipsilateral settings: Bennett side shift (1·0 mm), Bennett movement (30°) and the Sag. Condylar guidance (0°) as well as the Incisal angle (0°), which could be studied in the bucco‐lingual sections. Also the Bennett side shift on the contra‐lateral side influenced the occlusal contour strongly, which could be seen in the mesio‐distal section. It was concluded that simulation of the influence of several types of determinants of mandibular movement on the three‐dimensional occlusal anatomy can be studied using the CICERO‐CAD/CAM technique. The ipsi‐ and contralateral Bennett side shift variation influenced the occlusal anatomy more than other variables.     

Prevalence of torus palatinus among a group of Japanese elderly

Summary The purpose of this study was to examine the prevalence of torus palatinus (TP) among Japanese elderly and to identify the factors associated with the formation of TP. The subjects were adults aged over 60, who lived independently in the community and attended lectures once a week at the Senior Citizens’ College in Osaka prefecture during 2007 and 2008. A total of 664 subjects, including 294 men and 370 women, were examined, and the mean age was 66·5 ± 4·2 (s.d.). After informed consent was obtained, participants responded to a questionnaire and underwent clinical examination consisting of dental status, temporomandibular symptoms and occlusal force. There were 113 (17·0%) subjects with TP. The prevalence of TP was more frequent in women than in men (24·6% versus 7·5%, P < 0·01). Moreover, there was a significant relationship between the presence of TP and the presence of Torus mandibularis (13·3% versus 25·9%). There was no significant relationship between the prevalence of TP and other factors; diurnal and nocturnal bruxism, occlusal force, occlusal support and temporomandibular diseases symptom. Logistic regression analysis, in which adjustment was made for age and occlusal force, revealed a significant relationship between the presence of TP and gender and the presence of torus mandibularis (TM) (P < 0·001 OR = 3·43, 95%CI = 2·00–5·86; P < 0·001, OR = 2·63, 95%CI = 1·64–4·24, respectively). This study suggests that genetic factors play a more significant role than factors related oromaxillofacial function in the aetiology of TP.     

Rigidity evaluation of quartz‐fiber splints compared with wire‐composite splints

Abstract – Aim: To evaluate the influence of reinforcement material on in vitro dental splint rigidity. Materials and Methods: A custom‐made artificial model was used. The central incisors simulated ‘injured’ teeth with increased mobility, and the lateral incisors served as ‘uninjured’ teeth with physiologic mobility. The Periotest and Zwick methods were used to assess horizontal and vertical tooth mobility before and after splinting, and relative splint effect (SpErel) was calculated. Teeth 12–22 were splinted using two wire‐composite splints (WCS), WCS1 (Dentaflex 0.45 mm), and WCS2 (Strengtheners 0.8 × 1.8 mm) as well as four quartz‐fiber splints, QS1 (Quartz Splint UD 1.5 mm), QS2 (Quartz Splint Rope 1.5 mm), QS3 (Quartz Splint Woven 2.5 mm), and QS4 (dry fibers 667 tex). The influence of the splint type was evaluated using anova , Tukey range, and the Dunnett‐T3 test (α = 0.05). To test the influence of initial tooth mobility, the t‐test was applied (α = 0.05). Results: Reinforcement materials significantly influenced splint rigidity (P < 0.05). The horizontal and vertical SpErel of WCS1 compared with WCS2 and QFSs1–4 was statistically significant (P < 0.05). Significant differences were found when comparing the horizontal SpErel of WCS2 with WCS1 and QSs1–4 (P < 0.05). SpErels of the ‘injured’ and ‘uninjured’ teeth showed significant differences (P < 0.05). Conclusion: WCS1 is flexible compared with the more rigid WCS2 and QSs1–4. Initial tooth mobility influences SpErel. The flexible WCS1 can be recommended for splinting dislocation injuries whereas the semi‐rigid/rigid WCS2 and QS1–4 can be used for horizontal root fractures and alveolar process fractures. The QS1–4 provide good esthetic outcome.     

Prevalence of temporomandibular disorder signs in patients with schizophrenia

Summary The aim of this study was to determine the prevalence of temporomandibular disorder (TMD) signs in a group of institutionalized patients with schizophrenia. Three hundred thirty‐nine patients with schizophrenia were examined and compared with 107 age‐matched and gender‐matched control subjects. TMD signs were evaluated according to the Research Diagnostic Criteria to assess temporomandibular joint pain to palpation, limitation of maximum mouth opening, alteration of mouth opening pathway (deviation/deflection) and temporomandibular joint noises. In addition, tooth wear was recorded for the assessment of bruxism. The prevalence of any TMD signs was observed higher (P = 0·001) in the patients with schizophrenia (284/339, 83·7%) than in the controls (72/107, 67·3%). The prevalence of more than one TMD sign was also significantly higher (P = 0·03) in the patients with schizophrenia (131/339, 38·6%) than in the controls (29/107, 27·1%). Significant differences between the two groups were apparent for joint pain on palpation (P = 0·006), deflection (P = 0·006) and joint sounds (P = 0·002). Severe tooth wear was evident in 39·2% of the patients with schizophrenia compared with 21·2% in the control group (P = 0·001). The finding of the present study showed that, compared to control population, chronically hospitalized patients with schizophrenia seem to be more prone to the development of TMD signs and severe tooth wear and bruxism.     

Comparison of direct and indirect occlusal contact examinations with different clenching intensities

The aims of this study were to examine the change of occlusal contact area following the increment of clenching intensity using silicone materials and electromyography (EMG) in normal subjects and to compare direct intra‐oral examination with indirect examination using dental casts mounted by means of two impression methods. Participants were 7 men and 5 women with no more than one missing tooth per quadrant and no pain in the head and neck region. During the task, intercuspal position was maintained with minimal force, 20% maximum voluntary contraction (MVC) and 40% MVC using electromyography visual feedback. Three types of occlusal contact examinations were performed with the aid of blue silicone material in randomised order: (i) intra‐oral direct occlusal contact examination (DE), (ii) indirect occlusal contact examination with dental casts using conventional impression method (IEC) and (iii) using occlusal impression method (IEO). Total occlusal contact area during DE and IEO significantly increased from baseline to 20% MVC and from baseline to 40% MVC, but not during IEC. Total occlusal contact area during DE in all tooth clenching conditions was significantly larger compared to IEO and IEC (P < 0·05). At 40% MVC, total occlusal contact area during IEO was significantly larger than during IEC (P < 0·05). These findings suggest that indirect occlusal contact examinations may not accurately reflect the intra‐oral occlusal condition. If the intra‐oral condition is reproduced using dental casts, these findings also suggest the occlusal impression method was more accurate compared to the conventional method (240 words).     

Cervical wear and occlusal wear from a periodontal perspective

Summary The aim of this study was to investigate whether cervical wear was associated with occlusal wear and clinical periodontal parameters in relatively older adults. A total of 30 patients, with multiple non‐carious cervical lesions (NCCLs) and without a disease or condition that could cause heavy tooth wear, were included in the study. The periodontal parameters including plaque index, probing pocket depth, gingival recession (GR) and tooth mobility were obtained from 641 teeth of which 475 (74·1%) displayed NCCLs. The levels of cervical wear and occlusal wear were determined according to a tooth wear index. Premolars were more likely to develop cervical wear than canines, molars and incisors. Cervical wear was significantly associated with less plaque accumulation and the presence of shallow pockets. The teeth with advanced GR and without increased mobility were 2·583 and 1·715 times more likely to develop deeper cervical lesions, respectively. Age and the level of occlusal wear were not linked to the bucco‐lingual depth of cervical wear. In conclusion, the significant association of advanced cervical wear with the relatively healthy periodontal status suggested the role of abrasion and its possible combined action with erosion in the aetiology of NCCLs. The rate of GR and the lack of tooth mobility could constitute predisposing factors for the progression of cervical wear because the exposed root surfaces could be more susceptible to abrasion and/or erosion, and the non‐mobile teeth resisting strongly against frictional forces, thus abrasive effects, could possibly develop cervical wear.