A guide to the clinical management of attrition

Digital evaluation of occlusal reduction of metal crown preparations in students in the COVID-19 era: A cross-sectional study

Introduction

Occlusion of extra-coronal restorations depends on the reduction achieved during crown preparation. Ensuring adequate reduction is therefore essential for the success of the final restoration. The objective of this study was to digitally quantify the occlusal reduction performed by preclinical undergraduate dental students and to compare their performance across the year and using a hybrid teaching approach developed because of the COVID-19 pandemic.

Methods

Eighty full metal crown preparations on typodonts were scanned using the KaVo Arctica 3D Optical scanner. Occlusal reduction was measured using Autodesk Fusion 360 v2.0 by superimposing an unprepared tooth over the preparation and taking measurements at six occlusal points (mesio-buccal (MB), disto-buccal (DB), mesio-lingual (ML), disto-lingual (DL), mesial fossa (MF), and distal fossa (DF)). A general linear model was used to compare student performance in the mid vs final year exams and in 2018/19 vs 2020/2021.

Results

The adequacy of occlusal reduction was variable. Occlusal reductions of the MF (p = 0.014) and DF (p = 0.011) were significantly lower in the final exam than the mid-year exam in 2018/2019. There was also occlusal under-reduction at all six occlusal points in 2020/2021 compared with 2018/2019.

Conclusions

Students must be encouraged to use verification guides throughout the procedure to ensure adequate reductions. These verification methods can be as simple as putty indices or as advanced as optical scanners. The use of verification methods alongside a hybrid virtual and live teaching approach may guarantee the best results.

Interdisciplinary management of an adult patient with significant tooth wear

Adult patients may present with compromised dentitions which require extensive oral rehabilitation. This case report shows the fulfilment of both functional and aesthetic treatment objectives for a patient with significant tooth wear through carefully planned interdisciplinary management. © 2022 Australian Dental Association.

Epidemiology, aetiology and prevention of tooth wear

Tooth wear is a commonly reported finding globally; however, many patients are unaware of having tooth wear. Identifying early signs of erosion, abrasion or attrition and determining the risk factors contributing to a patient's tooth wear may help to prevent further loss of enamel and dentine in the future. Appropriate prevention should be instigated, or appropriate referral made to other health professionals, when conditions such as gastroesophageal reflux or eating disorders are suspected. This paper presents the epidemiology and aetiological factors for tooth wear, as well as identifying the common clinical presentations of tooth wear. Patient perspectives on tooth wear and preventive techniques that can be utilised are also discussed.

In vivo evaluation of the reliability and validity of three digital occlusion analysis methods

OBJECTIVES

The reliability and validity of three digital occlusion analysis methods was evaluated in vivo.

METHODS

The three method evalueated were:scanning of articulating paper marks (SA), dental prescale occlusal analysis system (DP) and a virtual occlusion constructed method (VO). A conventional silicone transmission method (ST) was used as the standard for comparison. Each of the 20 enroled human subjects was tested with the four methods. Retest of each method was performed at 2-week intervals. Occlusal contact area (OCA) and occlusal contact numbers (OCN) were calculated for analyses. For reliability evaluation, intraclass correlation coefficients (ICC) of the OCA and OCN values obtained from each method were compared. For validity evaluation, Pearson correlations coefficients, paired t-tests, regression analysis and Bland-Altman analysis were examined.

RESULTS

The ICC values of OCA and OCN were in the order: ST>SA>DP>VO. The highest OCA and OCN values were found ST while the lowest values were obtained from DP. Paired t-test identified a significant difference when OCA values obtained from the three digital methods were compared with ST, and between the OCN values of DP and ST. Pearson correlation showed high coefficients between ST and three digital methods (0.583-0.885 for OCA; 0.779-0.836 for OCN). A significant linear correlation was found between the results from ST and those from SA or VO. Bland-Altman analysis showed good agreement between OCN values of SA and ST, and between those of VO and ST.

CONCLUSIONS

The three digital occlusal analysis methods showed good reliability and validity for in vivo clinical application.

CLINICAL SIGNIFICANCE

The three digital occlusion analysis systems examined demonstrate good potential in in vivo quantitative analysis, with good reliability and validity. The use of these analytical methods should facilitate digital workflow in clinical practice.

Tooth Wear and Tribological Investigations in Dentistry

Dental or tooth wear is a physiological process in the life cycle of teeth. Loss of the occlusal surface may cause excessive tooth wear. Several factors may contribute to tooth wear with different intensities and duration in the oral cavity. The oral cavity is generally compared to a tribological system to determine the various types of wear between teeth and restorative materials and assess the amount of dental wear. However, it is challenging to investigate in vitro and in vivo wear owing to the complexity of tooth wear; thus, a clear correlation between in vitro and in vivo data could not be established. This review is aimed at providing an insight into the etiology of tooth wear and tribological investigations in dentistry.

Impact of Attrition, Intercellular Shear in Dry Eye Disease: When Cells are Challenged and Neurons are Triggered

The mechanical component in the pathophysiology of dry eye disease (DED) deserves attention as an important factor. The lubrication deficit induced impaired mechano-transduction of lid pressure to the ocular surfaces may lead to the dysregulation of homeostasis in the epithelium, with sensations of pain and secondary inflammation. Ocular pain is possibly the first sign of attrition and may occur in the absence of visible epithelial damage. Attrition is a process which involves the constant or repeated challenge of ocular surface tissues by mechanical shear forces; it is enhanced by the thinning of corneal epithelium in severe DED. As a highly dynamic process leading to pain and neurogenic inflammation, the identification of the impact of attrition and its potential pathogenic role could add a new perspective to the current more tear film-oriented models of ocular surface disease. Treatment of DED addressing lubrication deficiencies and inflammation should also consider the decrease of attrition in order to stimulate epithelial recovery and neural regeneration. The importance of hyaluronic acid, its molecular characteristics, the extracellular matrix and autoregulative mechanisms in this process is outlined. The identification of the attrition and recognition of its impact in dry eye pathophysiology could contribute to a better understanding of the disease and optimized treatment regimens.

Analysis of the sleep period and the amount of habitual snoring in individuals with sleep bruxism

Background

The literature does not report any association between habitual snoring and sleep bruxism, but these situations can be a reason for frequent complaints of individuals, impairing the quality of life. This study was performed to investigate the sleep period and amount of habitual snoring in individuals with sleep bruxism observing expiratory, inspiratory, and mixed snoring.

Material and Methods

A total of 90 individuals were screened and divided into the following groups: with sleep bruxism (n=45) and those without sleep bruxism (n=45). Single night sleep polysomnography was performed to diagnose sleep bruxism, quantify habitual snoring and sleep period. The results were tabulated and submitted to a Multivariate analysis of variance (MANOVA) to compare the means of the two independent groups, considering the affected diagnosis of sleep bruxism, snoring (independent variables) and age as covariate. For the post hoc, was used correcting for multiple comparisons (Bonferroni test, P <.05).

Results

There was statistically significant difference among the groups ( p =.001) in the sleep period, in that individuals with sleep bruxism slept for a longer duration (with sleep bruxism group: 460 minutes and without sleep bruxism group: 401 minutes). There were no statistically significant differences among the groups for the number of inspiratory, expiratory and mixed snores, but was observed greater amount of snoring in the with sleep bruxism group.

Conclusions

The main finding of this study is that individuals with sleep bruxism slept longer than the control group. It may also be suggested that individuals with sleep bruxism tended to increase the amount of habitual snoring during sleep.

Key words:Bruxism, adult, sleep disordered breathing, polysomnography.

Comparison of stress in implant-supported monolithic zirconia fixed partial dentures between canine guidance and group function occlusal patterns: A finite element analysis

Background. Monolithic zirconia is an emerging material for crowns and bridges. The possibility of full digital design has made it an attractive alternative material for implant-supported prostheses. A proper design is vital in the success of such a prosthesis like any other. This study, in the shortage of scientific evidence, has tried to assess the stress distribution of occlusal forces inside the implant-prosthesis system of a 3-unit bridge made of monolithic zirconia. Methods. A 3-unit monolithic zirconia bridge supported by two implant fixtures placed on the teeth #13 and #15 was digitalized. It was converted to a mesh of 59000 nodes and 34000 elements. Five types of occlusal forces (one as vertical centric, two at 15º and 30º simulating canine pattern of lateral movement, and two at 15º and 30º simulating group function pattern) were applied. The stress distribution among all the components of the implant-bridge system was assessed using Ansys Workbench 14 software and finite element analysis. Results. The maximum stress was between 286 and 546 MPa, which were found in either the fixture‒abutment screw area or in the upper part of the pontic connector between the canine and first premolar. The maximum pressure increased with an increase in the angle of occlusal force. Significantly higher stress was recorded in the group function occlusal pattern. Conclusion. Monolithic zirconia can be promising in designing bridges in the canine‒premolar area. However, proper design is necessary with more attention to the connectors and types of occlusal forces.

The Prevalence and Severity of Tooth Wear in Type 2 Diabetic Patients

Objective

To assess the prevalence and severity of tooth wear in type 2 diabetic patients.

Methods

Attendees at a diabetic clinic at Wiang Pa Pao Hospital in Chiang Rai province, Thailand, were invited to take part in this cross-sectional study. All participants were aged 35–74 and had type 2 diabetes. Participants were required to have been diagnosed with diabetes for at least three months. 179 subjects accepted a clinical oral examination and completed the questionnaire. Tooth wear was assessed clinically using the Smith and Knight Tooth Wear Index.

Results

The mean age of diabetic patients was 56.5 ± 7.8 years. The majority (44.1%) had diabetes more than 5 years. The average years of having had diabetes was 6.5 ± 6.3 years. The most prevalent type of tooth wear was attrition (99.4%). The prevalence of erosion, abrasion, and abfraction were 64.8%, 31.3%, and 7.3%, respectively. The majority of the tooth wear was moderate to high severity (62.1%). Erosion and abfraction showed significant association with age group (p < 0.05). Age group was significantly associated with the severity level (p=0.017). Mild tooth wear severity was the highest in age groups 35–44 and 45–54 (53.8% and 41.2%, respectively). Moderate tooth wear was the highest proportion in age groups 55–65 and 65–74 (52.2% and 44.0%, respectively). There were no significant differences between specific diabetic symptoms and types of tooth wear.

Conclusion

There was a high prevalence of tooth wear among diabetic patients. The role of prevention is vital in maintaining the integrity of the teeth and to avoid treating these worn teeth in diabetic patients.