Increase In Occlusal Vertical Dimension Research Articles

Influence on the temporomandibular joint induced by mandibular malpositioning caused by vertical dimension elevation and occlusal loss in adult rats: An imaging, histological and immunohistochemical study.

Mandibular malpositioning may result in an abnormal concentration of stresses within the temporomandibular joint (TMJ) in adult rats, which may further lead to a series of pathological changes, such as articular cartilage wear, subchondral bone sclerosis and osteophyte formation. However, the pathological and adaptive changes in condylar cartilage caused by different stress distributions are still controversial. The aim of this study was to observe the effect of sagittal changes in mandibular position on condylar cartilage by changing the occlusal vertical dimension (OVD) in adult rats. Fifteen-week-old female rats were divided into three groups: control (CON), increased OVD (iOVD) and loss of occlusion (LO) groups. An occlusal plate and tooth extraction were used to establish the animal model. TMJ samples of the experimental and CON groups were observed and investigated by bone morphological, histomorphological and immunohistochemical staining analyses at 3 days, 1 week, 2 weeks, 4 weeks and 8 weeks. Weight curves were plotted. Micro-computed tomography showed that, compared with the CON group, cartilage destruction followed by repair occurred in both experimental groups, which was similar to the trend observed in haematoxylin-eosin staining. All experimental results for the iOVD group showed an approximately similar time trend. Compared with the iOVD group, the toluidine blue and immunohistochemical staining results in the LO group showed no obvious change trend over time. Compared with occlusal loss, an increase in OVD caused faster and more severe damage to condylar cartilage, and subchondral bone repair occurred later.

A case report of improvement in stability of dentures and lip support by increase of occlusal vertical dimension

A case report of improvement in stability of dentures and lip support by increase of occlusal vertical dimension

Effect of Increasing Occlusal Vertical Dimension on Smile Parameters

Introduction: Increasing Occlusal Vertical Dimension (OVD) becomes important aspect of complex prosthodontic treatment for maintaining balance between form of oral structures and function of stomatognathic system. The purpose of this study is to determine the effect of increasing OVD on various smile parameters during posed smile. Methodology: This observational descriptive study included 30 patients, 14 male and 16 females, visiting dental department of National Academy of Medical Sciences (NAMS), Bir Hospital. Four polyvinyl siloxane bite records were fabricated on stone cast mounted on a semi-adjustable articulator increasing OVD by +1 mm, +2 mm, +3 mm and +4 mm taking incisal pin as a reference. Photographs of posed smile were taken at OVD of +0 mm, +1 mm, +2 mm, +3 mm and +4 mm using a DSLR camera mounted on a tripod. Head position was stabilized using a head positioning device of a cephalometric unit during photography. Adobe photoshop CS6 extended was used to calculate the various measurement in pixel which was converted into mm with help of conversion ratio obtained. Data were then processed and analyzed using SPSS software at the 5 % significance level. Result: One-way repeated measures ANOVA found statistically significant differences in interlabial gap height, incisal edge to lower lip distance, smile index and display zone area with increasing OVD. No statistically significant differences were found for intercommisural width and incisal edge to upper lip distance. Conclusion: Within the limitations of this study, the excessive increase of OVD may lead to excessive interlabial gap height, incisal edge to lower lip distance, and display zone area. Also, the increase of OVD may lead to reduced smile index. No change may be expected in the position of the upper lip with increase of OVD. In addition, a change in the intercommisural width of the smile should not be expected with increasing OVD.

Treatment of localized anterior toothwear with composite restorations at an increased occlusal vertical dimension

Patients may present with localized anterior toothwear, complaining of poor appearance or sensitivity. or both. Restoration of these teeth continues to cause problems, especially if interocclusal space has been lost. Conventional treatment to satisfy the patient's aesthetic and functional demands is time consuming and requires careful maintenance. This paper describes the use of chairside composite resin restorations in the treatment of localized anterior toothwear. lnteroccusal space is provided by placing the restorations at an increased vertical dimension of occlusion. It enables the presenting complaint to be resolved while restoring structure, function and appearance. CPD/Clinical Relevance: Localized anterior toothwear may be treated in suitable cases by placement of palatal composite restorations, with posterior tooth contact normally being re-established within 6 months. Original article reproduced in full from: Darbar UR, Hemmings KW. Treatment of localized anterior toothwear with composite restorations at an increased occlusal vertical dimension. Dent Update 1997; 24: 72–75. (Please note that the figures have been reproduced from the original printed version.)

Increased Occlusal Vertical Dimension and Its Influence on Lip Position at Smile in Dentulous Adults

Introduction: Increasing occlusal vertical dimension (OVD) is often indicated in complex prosthodontic rehabilitations to gain restorative space and improve the occlusal relationship and esthetics. However, any alterations made in OVD will also influence the lip position mainly during rest and smile. This study aims to determine the influence of the vertical dimension of occlusion on lip positions at a smile. Methods: 30 samples between the age group of 20 - 30 years were included in this study meeting the selection criteria. The acrylic splint of varying thicknesses of +2mm, +4mm, +6mm, +8mm was prepared on the dental stone cast of a patient that was articulated in a semi-adjustable articulator after tentative facebow transfer. Smile photograph of each individual at the occlusal vertical dimension of +0mm, +2mm, +4mm, +6mm, +8mm was taken using a DSLR camera mounted on a tripod using the prepared acrylic splints. Digital measurements were done in photographs using the Adobe Photoshop software. Results: The study's results demonstrate that increasing the OVD significantly affects the inter labial distance, incisal edge to lower lip distance, and the display zone area. However, the study found no notable alterations in the distance from the incisal edge to the upper lip or in the intercommissural width with the same increased OVD. These findings demonstrate on how changes in OVD can influence various orofacial measurements. Conclusion: Within the limitation of this study, it can be concluded that with the increase in the OVD, inter labial distance, incisal edge to lower lip distance, and display zone area are increased. But upper lip position and inter commissural width should not be expected to be changed with increased OVD.

Patient satisfaction following resin-bonded fixed dental prostheses cemented by using the Dahl concept.

Resin-bonded fixed dental prostheses (RBFDPs) cemented at an increased occlusal vertical dimension (OVD) (the Dahl concept) to create space for a metal retainer remains controversial because of the lack of reported clinical studies. This study analyzed the demographic (age and sex) and clinical factors (location and arch of prosthesis) affecting the patients' perception of RBFDPs cemented at an increased OVD. Twenty-eight participants treated with cantilevered RBFDP at an increased OVD were prospectively recruited. They were asked to answer a validated patient satisfaction questionnaire based on six parameters during the 12-week review visit. 71.4% of the participants were completely satisfied with the color, shape, and function. Twenty-one (75%) participants reported no complaints about the prostheses. 89.3% will recommend this treatment option to others. There was a significant difference between males and females in avoiding loading on the prostheses (p = 0.015). The level of satisfaction did not differ by age, ethnicity, location, and arch of the prostheses (p > 0.05). Patient satisfaction toward RBFDP cemented by using the Dahl approach was generally high on all the parameters at the 12-week review visit.

Rehabilitation with minimal increase in occlusal vertical dimension in a patient with excessive tooth wear and edge-to-edge bite

Rehabilitation with minimal increase in occlusal vertical dimension in a patient with excessive tooth wear and edge-to-edge bite

Assessment of Occlusal Vertical Dimension Change in Mechanical and Virtual Articulation: A Pilot Study.

The aim of this clinical study was to investigate the change in occlusal vertical dimension (OVD) with dental casts mounted on a mechanical articulator using an average axis facebow and on a virtual articulator mounted using the Bonwill triangle and the Balkwill angle and compare these groups with OVD change observed clinically in patients. Casts were obtained from each patient (n = 14) and mounted on a semi-adjustable articulator in the facebow preservation group (FPG) and on a virtual articulator using average anatomic values in the average mounting group (AMG). Customized mandibular anterior splints were virtually designed at an OVD increased by 3, 6, and 9 mm. Digital buccal scans were performed with the anterior devices in the participants' mouths in the intraoral group (IOG), AMG, and FPG at the different OVD increases accordingly. While no statistically significant differences (p > 0.05) were observed in the posterior interocclusal measurements with the incisal guide pin raised by 3 mm and 6 mm among all groups, a 9 mm increase resulted in a significant difference between AMG and IOG. The interocclusal posterior-to-anterior opening ratio observed clinically was 1:1.575. Increases in OVD up to 6 mm on dental casts mounted using average anatomic values performed similarly to the actual intraoral changes.

Occlusal Considerations and Multidisciplinary Approach in the Rehabilitation of Generalised Tooth Surface Loss

Tooth wear is prevalent in the society and often-time affects an individual’s daily life. This case demonstrates the management of non-carious tooth surface loss with loss of occlusal vertical dimension using multidisciplinary approach involving periodontics, endodontics and prosthodontics. The tooth surface loss was graded moderate to severe anteriorly and affecting the patient’s overall appearance and self-confidence. Rehabilitation of this case involves restoring the anterior teeth at an increased occlusal vertical dimension, using reorganised approach and allowing relative axial tooth movement posteriorly. Clinical Relevance: The author believes the understanding of available conservative treatment options, occlusion concepts, proper material handling and satisfactory communication with other disciplines and the laboratory aid a clinician in achieving the best treatment outcome and better patient satisfaction.

Development of a Clinically Relevant Index for Tooth Wear Treatment Needs.

Background: This study aimed to develop a tooth wear classification system that combined the extent, severity, and aesthetic impact of tooth wear and correlated them with the most appropriate clinical management strategy. Methods: Three hundred photographs were used to develop a classification tool that contained four levels of severity and aesthetic impact (0, 1, 2, and 3) in three age groups of patients. Ten examiners assessed and classified the cases using validated forms. Additionally, they selected the recommended treatment modality for each level. The analysis was conducted using a coefficient correlation test. Results: The coefficient correlation for the severity was 0.81, 0.82 in the upper anterior and posterior segments, and 0.85 and 0.77 for the lower anterior and posterior segments, respectively. The aesthetic impact correlation coefficient was 0.84. Examiners had agreed that minor cases required monitoring or simple restorative interventions. The moderate-level cases had variety in the recommended management options depending on the aim of treatment. The severe level cases often required rehabilitation at an increased occlusal vertical dimension. Conclusion: Within the limitations of this preliminary study, a good agreement between the examiners was found using the provided tools. More strict criteria in the classification part of the tool can further improve the examiners’ agreement.

The Restoration of Severe Generalized Dental Erosive Wear using Direct Composite: A Case Report

Introduction: This case report describes a conservative restorative approach in the management of severe generalized tooth wear. Case report: The male, aged 57 years, was mainly concerned with the poor appearance of his teeth with short and discolored upper incisors. History revealed that he suffered from gastric reflux for 25 years, for which he was prescribed Ranitidine and was advised to self-medicate with cider vinegar. Furthermore, he divulged that he ground his teeth at night and during the day and had a high intake of carbonated cola drinks. On examination, dentine was exposed in several areas, and to a significant extent, on the incisal aspects of the lower incisors, the palatal surfaces of the upper incisors, and the occlusal surfaces of the molars. Mandibular tori were present. The primary diagnosis was erosive tooth wear with elements of attrition and abrasion. The intervention included dietary advice and restoration with direct composite resin at an increased occlusal vertical dimension of 1.5mm on the retruded axis. The patient reported no functional problems and was pleased with the aesthetic result. Conclusion: Vinegar is promoted to have health benefits, especially with respect to glucose response, but the dental implications are overlooked. This paper reviews the literature on vinegar as a medicament and considers its role as a co-factor for erosion in this case. The clinical steps used to restore the eroded dentition by direct composite are described. The use of this approach is a safe, conservative and successful treatment option without recourse to complex and biologically costly conventional alternatives. The application of direct composite in tooth wear cases meets the European consensus requirements.

Effect of short-term increase in occlusal vertical dimension on masticatory muscle electrical activities and pressure-to-pain threshold: A crossover clinical study

Statement of problemIncreasing the occlusal vertical dimension (OVD) is a common procedure in clinical practice. However, few studies have assessed the short-term influence of an increased OVD on the masticatory muscles. PurposeThe purpose of this crossover clinical study was to investigate the effect of increased OVD on the electrical activity of masticatory muscles and the pressure-to-pain threshold (PPT) in asymptomatic participants. Material and methodsTwenty asymptomatic participants (22.7 ±2.39 years of age; 10 men, 10 women) were submitted to an increase in OVD by using interocclusal devices of different thicknesses (3- and 6-mm) for 24 hours. Masticatory muscle activity was assessed with electromyography (EMG), expressed in microvolts (μV), while the participants masticated 2 pieces of latex of different consistency (latex S and H) with and without the device. The PPT was measured with a digital algometer before and after the mastication. The results were assessed by using analysis of variance (ANOVA) and the Tukey honestly significant difference (HSD) test (α=.05). ResultsThe change of OVD did not significantly affect the electrical activity of the muscles. The latex of hard consistency (latex H) showed higher electrical activity values than the soft texture (latex S). For the working side anterior temporal muscle, a change in the PPT was detected on the day the 6-mm-device was inserted, but for the other muscles, device thickness and latex mastication did not change the PPT. ConclusionsFor a short time, an increase in occlusal vertical dimension did not affect the electrical activity in the masticatory muscles or pressure-to-pain threshold in asymptomatic participants.

Occlusal force and occlusal contact reestablishment with resin-bonded fixed partial dental prostheses using the Dahl concept: A clinical study

Statement of problemSpace creation for a metal retainer of the resin-bonded fixed partial dental prostheses (RBFPDPs) with the Dahl concept remains controversial because of the lack of clinical studies. PurposeThe purpose of this clinical study was to investigate the occlusal force and occlusal contact reestablishment of RBFPDPs cemented at an increased occlusal vertical dimension (the Dahl concept) and to evaluate the factors affecting them. Material and methodsA prospective clinical study was carried out on 28 participants receiving cantilevered RBFPDPs at an increased occlusal vertical dimension at the Faculty of Dentistry, University Teknologi MARA. Maximum occlusal forces were recorded at precementation, postcementation, and 12-week review visit by using pressure indicating film, while occlusal contact reestablishment was assessed at the precementation stage and 12-week review visit by using shim stock foils. The Wilcoxon signed-rank and chi-squared tests were used for statistical analysis (α=.05). ResultsSignificant differences were found for maximum occlusal force between the precementation and the postcementation and between the postcementation and the 12-week review of RBFPDPs (P<.05 for both) in all 28 participants. However, no significant difference was found between the precementation and the 12-week review (P=.085). The occlusal force reestablishment concerning sex, age, location, and arch of the prosthesis was found to be similar. Most of the participants (89.3%) achieved complete occlusal contact reestablishment and 10.7% partial occlusal reestablishment. The demographic and prosthesis factors were not significantly related to the occlusal reestablishment (P>.05). ConclusionsOverall, occlusal force was reestablished after 12 weeks, and occlusal contact was completely reestablished in most participants after placement of RBFPDPs at an increased occlusal vertical dimension.

Rehabilitation of a Severely Worn Dentition with Partial Lithium-disilicate Glass Ceramic Restorations: A Case Report

Rehabilitation of worn dentition is a challenging task because several predisposing factors may be included in the pathogenesis. The treatment options and process should be carefully considered based on the clinical condition and patients’ requirements. This case report represents the esthetic rehabilitation of a 68-year-old patient who exhibited severely worn teeth caused by attrition and erosion. After clinical evaluation, 3 mm increase in occlusal vertical dimension was planned with partial lithium-disilicate ceramic restorations as laminate veneers for anterior teeth and vonlays (onlays with veneer extentions) for posterior teeth in maxilla. The adaptation of the patient to the increased occlusal vertical dimension was tested for 1 month by provisional direct composite restorations. As the patient did not show any discomfort, definitive restorations were completed. The patient was satisfied with the esthetics and functionality of her new dentition.

Occlusal re-establishment and clinical complications of resin-bonded fixed partial dental prostheses cemented at an increased occlusal vertical dimension: A retrospective study

Statement of problemResin-bonded fixed partial dental prostheses (RBFPDPs) cemented at an increased occlusal vertical dimension (OVD) (the Dahl concept) to create space for a metal retainer remain controversial because of the lack of reported clinical studies. This study evaluated RBFPDPs by applying the Dahl concept. PurposeThe purpose of this retrospective study was to investigate the clinical factors affecting the occlusal re-establishment and short-term complications of RBFPDPs cemented at an increased OVD. Material and methodsOcclusal re-establishment and clinical complications were reviewed in 109 participants (155 RBFPDPs) treated at the Faculty of Dentistry, Universiti Teknologi MARA from January 2013 to May 2018. Types of complications and risk factors were assessed from clinical data. Demographic factors, clinical factors, and prosthesis factors were distinguished and their association with occlusal re-establishment analyzed by using multiple regression analysis. ResultsA total of 155 RBFPDPs (42 anterior, 113 posterior) were placed in 109 participants. All achieved occlusal re-establishment, 89.9% complete occlusal re-establishment and 10.1% partial occlusal re-establishment, a minimum of 4 months after the RBFPDPs had been placed at an increased OVD. The design of the metal retainer coverage was found to be a significant factor affecting occlusal re-establishment and decementation (P<.05). Widening of the periodontal ligament space was the most common complication (29.2%). ConclusionsRBFPDPs cemented at an increased OVD can be clinically recommended. The design of the retainer coverage was a significant factor influencing occlusal re-establishment and clinical complications.

Effect of increasing occlusal vertical dimension on lower facial form and perceived facial esthetics: A digital evaluation

Statement of problemIncreasing occlusal vertical dimension (OVD) is often indicated in complex prosthodontic rehabilitations to gain restorative space and improve the occlusal relationship and esthetics. The effect of increasing occlusal vertical dimension on lower facial height (distance from subnasale to soft-tissue menton) and perceived facial esthetics is not well understood. PurposeThe purpose of this clinical study was to investigate the effect of incremental increases in the occlusal vertical dimension on lower facial height and perceived facial esthetics by using a digital approach. Material and methodsTwenty-five participants with Class I jaw relationship and no loss of OVD participated in the study. Custom mandibular devices were digitally designed and 3-dimensionally printed to increase the OVD by 3, 6, and 9 mm in each participant. Three-dimensional facial scans and frontal photographs were made with the participants wearing a specific device to achieve the desired OVD increase. The lower facial height, total facial height (distance between nasion to soft-tissue menton), nasolabial angle, lip width, and lip height were digitally measured on facial scans. All measurements were recorded in a computer-aided design (CAD) software program and were repeated 3 times. Subsequently, frontal photographs of 10 participants were randomly selected for survey. Three groups each of 10 prosthodontists, general dentists, or laypersons participated in the survey and were asked to detect OVD difference in 2 photographs of the same participant and to rank facial esthetics at varying OVDs. One-way repeated measures ANOVA (α=.05) for the facial measurements and descriptive statistics for the survey results were used. ResultsLower facial height, the ratio of lower facial height to total facial height, lip height, and nasolabial angle increased with an OVD increase, whereas lip width decreased (P<.001). Bonferroni corrected paired t tests revealed all groups of OVD increase to be significantly different from each other (P<.001) except for an OVD increase to 6 mm versus 9 mm in lip height (P=.540) and lip width (P=.019), respectively. Prosthodontists, general dentists, and laypersons could detect a +3 mm OVD increase 63.9%, 62.5%, and 56.5% of the time, respectively. The participants’ original OVD was considered the most esthetic (60.0%, 45.0%, and 68.0%) by prosthodontists, general dentists, and laypersons, respectively. ConclusionsIncreased OVD increases lower facial height, the ratio of lower facial height to total facial height, lip height, and nasolabial angle but decreases lip width. Prosthodontists are more sensitive to a smaller increase in OVD, closely followed by general dentists and then laypersons. In case of no loss of OVD, a vertical increase as small as 3 mm can be detected by both dentists and the general public and perceived as less esthetic. The larger the increase in OVD, the more detectable the difference and the less the faces are perceived as esthetic.

Evaluation of Masticatory Muscle Function Using Digital versus Traditional Techniques for Mockup Fabrication: A Controlled Prospective Study

Background: the aim of this longitudinal prospective study was to analyze the effect of digital and traditional mockup on masticatory muscle activity in patients with teeth wear, rehabilitated with an increase of occlusal vertical dimension. Subjects and Methods: a sample of 22 adult patients who were about to receive a prosthetic rehabilitation was divided into a study group (3M; 9F; mean age 42 ± 0.8 years), treated using the digital mockup; and a control group (2M; 8F; mean age 37 ± 0.5 years), treated using the conventional technique (traditional) mockup. Electromyographic activity of anterior temporalis and masseter muscles were evaluated before the beginning of the treatment (T0), at mockup insertion (T1), after treatment (T2) and each lapse of time lasted 2–5 months. Results: the comparison between the two groups at different time gaps revealed that at ∆1 (T1–T0) only the impact index (IMP) showed significant difference and no other significant variation was observed between the two groups at ∆2 (T2–T1) and ∆3 (T2–T0). It concludes that traditional and digital methods generally have nonsignificant differences. Conclusions: both methods seem to be effective in prosthetic rehabilitation and give comparable effects on masticatory muscles.

Effectiveness of the increase of the occlusal vertical dimension in the smile of young Peruvian adults: A quasi-experimental study

Aim: To evaluate the increase of the occlusal vertical dimension (OVD) on the smile in young Peruvian adults. Materials and Methods: This quasi-experimental study included a total of 30 subjects (15 men and 15 women) aged between 20 and 30 years. Silicone stops were created that increased the OVD by 2 and 4 mm. Photographs were taken with a reflex camera of position, at programmed and standardized lighting, with and without the stops made to the patients using a head and face positioner. The following measurements were made: smile index, interlabial distance, intercomisural width, distance of the incisal edge–upper lip, and distance of the incisal edge–lower lip. The analysis of variance test was used for statistical analysis, establishing a level of significance at P < 0.05. Results: The measure of the interlabial distance of the initial smile was 10.70 ± 2.80 mm, in which the OVD became 11.79 ± 3.67 mm with the increase of 2 mm and 12.91 ± 3.98 mm with the increase of 4 mm; however, the increase in OVD favored a decrease on the smile index, decreasing from 6.07 ± 1.51 mm to 5.48 ± 1.24 mm and 4.99 ± 1.47 mm in the group of increases in the OVD of 2 and 4 mm, respectively. Conclusion: The increase of the OVD favors an increase in the interlabial distance and the measure from the incisal edge to the lower lip; however, it produces a decrease in the smile index in the young Peruvian patients evaluated.

Influence of occlusal vertical dimension on lip positions at smile in completely dentulous adults.

Aim:The study was conducted to evaluate the effect of increased vertical dimension on the lip positions at smile in dentulous subjects.Settings and Design:Invivo - comparative study.Materials and Methods:Thirty individuals aged between 22 and 30 years were selected for the study. Poly-vinyl siloxane (Jet Bite, Coltene, Switzerland) interocclusal bite records of varying thickness of +1, +2, +3, and +4 mm were made using articulated stone casts for all the participants, respectively. Posed smile photographs at different increased vertical dimensions of +1, +2, +3, and +4 mm were captured with D-SLR camera (Nikon D3200 of 18 megapixels with macro lens, Japan) mounted on tripod stand keeping a uniform distance of five feet from the face. Head positioning device (Genoray CBCT Machine Papaya 3D Plus, Unicorn DenMart, India) was used to stabilize the head position of the participants. Interlabial gap height, intercommissural width, smile index (width/height ratio), incisal edge-to-upper lip distance, incisal edge-to-lower lip distance, and display zone area measurements were made in AutoCAD software (Autodesk, Inc., California, USA).Statistical Analysis Used:One-way repeated measures ANOVA tests (α = 0.05) and Bonferroni's post hoc tests were performed for statistical analysis.Results:With increasing occlusal vertical dimension, the interlabial gap height, incisal edge-to-lower lip distance, and display zone area increased significantly (P < 0.001). The smile index decreased significantly as the occlusal vertical dimension increased (P < 0.001). No significant difference was found in intercommissural width and incisal edge-to-upper lip distance.Conclusion:It was found that an increase in occlusal vertical dimension led to an increase in interlabial gap height, incisal edge-to-lower lip distance, and display zone area measurements, whereas the width of smile and incisal edge-to-upper lip distance did not change with increasing occlusal vertical dimension.

The Survival Of All Ceramic Crowns With A Zirconia Core (Lava™)

Background: Few studies have assessed the survival of restorations and particularly zirconia based crowns in the restoration of the severely worn dentition. This study aimed to determine survival and factors associated with failure in anterior teeth worn through to dentine restored with Lava™ crowns. Methods: A convenience sample of 30 participants (27 male, 3 female) had 161 Lava™ crowns placed by one specialist clinician in a hospital setting. Follow-up was over a median 72 month period. Results: Of the 161 Lava™ crowns only 25 failed (15.5%) in 15 individuals up to 84 months for the longest case. Major failures were total debond (N=7) or minor delamination chips within the veneer ceramic layer (N=18). The mean time to first failure was 25.23 months. The Kaplan Meier survival plot estimated the Mean Survival Time for the crowns to be 74 months (95%CI 70.4, 77.3). Failures by subject were not associated with an increase in Occlusal Vertical Dimension using a Dahl approach but were associated with an edge-to-edge incisal relation (p&lt;0.05), attrition (p&lt;0.05) and bruxism (p&lt;0.005). Conclusion: The Kaplan Meier survival plot estimated the Mean Survival Time for the crowns to be 74 months. The high loads in bruxism result in increased risk of fracture or debond. Clinical relevance: A protective bi-laminar splint is thus advisable. Nonetheless, application of zirconia based crowns in a difficult clinical situation such as bruxism can be a successful treatment modality.