Tooth wear: A systematic review of treatment options

Treatment decisions of patients with Class II Division 2 malocclusion and severe tooth wear: a systematic review

BACKGROUND

The treatment strategy for patients with severe tooth wear associated with Class II Division 2 malocclusion remains a major challenge for dental practitioners.

OBJECTIVES

To systematically review and summarize the literature on treatment strategies, restoration procedures and clinical outcomes for Class II Division 2 malocclusion patients with severe tooth wear.

METHODS

A literature review was conducted using Pubmed, Embase, the Cochrane Library, and Web of Science to identify eligible articles. Publications until October 16th, 2023 were searched independently and cross-checked by two researchers.

RESULTS

Of 1513 articles screened, 10 reports detailed treatment processes, including six males and four females aged 34-68 years old. Four articles recorded pre-treatment freeway space (FWS) values ranging from 5 to 9 mm. All ten cases had significant occlusal vertical dimension (OVD) loss and the increase in OVD after treatment ranged from 1 to 7 mm. Pre-prosthetic orthodontic treatment was performed in two cases, in one of which only the maxillary region was orthodontically treated. The most common restorations provided were full coverage restorations. In most cases, temporary restorations were applied before the permanent restorations for eight weeks to six months. Four different sequences of final restoration were proposed. Follow-up ranged from four months to six years and included seven patients, one of them showed symptoms of temporomandibular disorder (TMD).

CONCLUSIONS

A multidisciplinary team (MDT) approach to treatment is recommended. Consideration of pre-prosthetic orthodontic treatment is essential. Commonly used cephalometric measurements for anterior teeth include the interincisal angle and collum angle. The increases in OVD ranging from 1 to 7 mm can be effectively accommodated. Temporary restorations are recommended to accommodate the OVD, and the transition periods of 8 weeks to 6 months help the patients adapted well. Four different sequences for final rehabilitation have demonstrated positive clinical outcomes. Full crown restorations have emerged as the preferred choice for the ultimate restoration of these patients.

Biomimetic Self-Maturation Mineralization System for Enamel Repair

Enamel repair is crucial for restoring tooth function and halting dental caries. However, contemporary research often overlooks the retention of organic residues within the repair layer, which hinders the growth of dense crystals and compromises the properties of the repaired enamel. During the maturation of natural enamel, the organic matrix undergoes enzymatic processing to facilitate further crystal growth, resulting in a highly mineralized tissue. Inspired by this process, a biomimetic self-maturation mineralization system is developed, comprising ribonucleic acid-stabilized amorphous calcium phosphate (RNA-ACP) and ribonuclease (RNase). The RNA-ACP induces initial mineralization in the form of epitaxial crystal growth, while the RNase present in saliva automatically triggers a biomimetic self-maturation process. The mechanistic study further indicates that RNA degradation prompts conformational rearrangement of the RNA-ACP, effectively excluding the organic matter introduced earlier. This exclusion process promotes lateral crystal growth, resulting in the generation of denser enamel-like apatite crystals that are devoid of organic residues. This strategy of eliminating organic residues from enamel crystals enhances the mechanical and physiochemical properties of the repaired enamel. The present study introduces a conceptual biomimetic mineralization strategy for effective enamel repair in clinical practice and offers potential insights into the mechanisms of biomineral formation.

Declarative knowledge in oral health: The case of the term 'centric occlusion'

INTRODUCTION

The lack of academic agreement in the practical or clinical use of declarative knowledge can generate unnecessary confusion and miscommunication. The concept Centric Occlusion (CO) is part of the body of declarative knowledge in dentistry, but its definition remains unclear.

OBJECTIVE

To ascertain the CO concept in articles published in dental journals as a study case for the dentistry "corpus" of declarative knowledge.

METHODOLOGY

The alternative definitions of CO used by the GPT (Glossary of Prosthodontic Terms) from 1956-1977, 'CO as a synonym for maximum intercuspal contact (MIC)', or by the GPT from 1987-2017, 'CO may or may not coincide with MIC', were searched in the articles. The association between the CO definition used and variables such as article aims, journal scope and authors specialty was assessed.

RESULTS

Eight hundred and twelve articles were analysed. The widespread use of CO as synonym of MIC was the main finding and was significantly associated to the Orthodontics field. The CO definition according to the GPT 1987-2017 was less frequently observed but appeared in all dentistry fields, showing a significant association with the Oral Rehabilitation field. The difficulty of incorporating the current definition of CO (by GPT) into the main clinical discussions was evidenced all the long of the review process.

CONCLUSION

The lack of consensus in the concept use was confirmed by the present study case, showing the influence of specific fields in Oral Health declarative knowledge. This methodology can provide a tool to the academy to assess controversial terms or concepts in Oral Health education, thus facilitating the critical and reflexive learning by students.

Reliability of digital repeated-scan superimposition and single-scan techniques for wear volume loss assessment on flat surfaces

OBJECTIVES

Evidence on the reliability of digital techniques for wear volume assessment using three-dimensional (3D) scan datasets is scarce. This study evaluated the reliability of a repeated-scan superimposition technique and two single-scan techniques in assessing wear volume loss on flat surfaces of 3D-printed resin specimens.

METHODS

Cuboid-shaped (15×10×10 mm) resin specimens were 3D-printed (n = 14) and scanned before and after 200,000 cycles of masticatory simulation. For the repeated-scan superimposition technique, digital 3D models of specimens before and after masticatory simulation were superimposed, and the volume loss was determined. The first single-scan technique utilized a computer-aided design freeware program, while the second one employed a 3D-metrology software program. In the freeware program, the worn area of 3D objects was edited directly to obtain a flat surface. In the 3D-metrology software program, the worn area was deleted first and then filled to the flat surface. The volume differences before and after editing were calculated in each software program. Agreement between the three measurement techniques was determined through intraclass correlation coefficients (ICCs). One-way analysis of variance was performed to compare the wear volume loss assessed by the three techniques (α = 0.05).

RESULTS

High inter-technique reliability was observed between the three assessment techniques (ICC = 0.998, p < .001). On pair-wise comparisons of two of the three techniques, all pairs showed high consistency (ICC ≥ 0.999, p < .001). No significant difference was found in the wear volume loss assessed using the three techniques (p = .996).

CONCLUSIONS

Digital repeated-scan superimposition and two single-scan techniques demonstrated high reliability in assessing wear volume loss on flat surfaces.

CLINICAL SIGNIFICANCE

The repeated-scan superimposition technique can be effectively utilized to assess wear volume loss of anatomically shaped specimens and flat surfaces. This study indicates that the single-scan techniques may serve as a suitable alternative to the repeated-scan superimposition technique when evaluating wear volume loss of flat surfaces.

Longevity of Anterior Composite Restorations for Localized Tooth Wear: A Scoping Review

(1) Objective: This scoping review evaluates composite restorations as a treatment modality for anterior tooth surface loss and investigates the longevity of the direct and indirect composites used herein. (2) Method: The search encompassed Medline, Embase, Web of Science, the Cochrane Library, and hand search utilizing the PICO framework. (3) Results: Eight studies were included in this review, comprising one randomized controlled trial, one retrospective, and six prospective studies. Some studies reported favorable outcomes for composite restorations in anterior teeth. Although not statistically significant, evidence supported the anterior composite as a viable short- to medium-term solution for managing tooth wear. Direct resin composites were deemed clinically and cost-effective when managing localized anterior tooth wear. However, limitations and inconsistencies in this scoping review limited definitive clinical recommendations. (4) Conclusions: Further research, including well-managed randomized controlled trials using standardized protocols and longer follow-up periods, is essential to reconfirm the long-term efficacies of anterior composite restorations when managing tooth wear. A robust research design and exacting protocols could facilitate more meaningful clinical conclusions.

The longevity of tooth-coloUred materials used for restoration of tooth wear: an evidence-based approach

Patients with tooth wear are commonly encountered in general dental practice. When indicated, restorative rehabilitation is often accompanied by a request from the patient for an aesthetic, tooth-coloured outcome. This article seeks to provide an evidence-based approach, focussing on the longevity of the materials which can be used for the restorative treatment of tooth wear, as well as their modes of failure and observed performance.

Surface Properties and Wear Resistance of Injectable and Computer-Aided Design/Computer Aided Manufacturing-Milled Resin Composite Thin Occlusal Veneers

OBJECTIVES

 This study was conducted to investigate the microhardness, surface roughness (Ra), and wear behavior of thin occlusal veneers (TOV) fabricated from different injectable composite materials and compare them to a Computer-Aided Design (CAD)/Computer-Aided Manufacturing (CAM) resin-based material.

MATERIALS AND METHODS

 A 1-mm occusal veneer preparation was done in a mandibular right second molar typodont tooth. The prepared model was duplicated to fabricate 32 replicas and divided into four groups (n = 8). Standard TOV were fabricated either indirectly from Cerasmart blocks, Cerasmart, GC (CS), or directly from Beautifil Injectable X, Shofu (BF), G-ænial Universal injectable, GC (GU), or SonicFill 2, Kerr (SF) using the injection molding technique. All the specimens were subjected to both thermomechanical cyclic loading (TMC) in a chewing simulator. Wear measurement was conducted by three-dimensional (3D) scanning of the veneered models before and after TMC, and the difference in the volume of the sample was recorded as the volumetric material loss due to wear. Ra before and after TMC and Vickers microhardness (VHN) of the tested materials were measured using standardized samples (n = 8). Representative samples from each group were investigated under a stereomicroscope and a scanning electron microscope.

STATISTICAL ANALYSIS

 One-way analysis of variance (ANOVA) was applied to detect the effect of material on VHN and wear. Two-way ANOVA was utilized to examine the impact of material and TMC on Ra. Multiple comparisons between the groups were conducted using Tukey's post hoc test (α = 0.05). The Pearson's correlation coefficient was used to determine the relationship between hardness and wear and between roughness and wear (α = 0.05).

RESULTS

 CS exhibited the highest mean VHN (p ≤ 0.001), followed by GU and SF which were statistically similar (p = 0.883) but significantly higher than BF (p < 0.001). After TMC, GU revealed the lowest Ra and volumetric wear (VW), followed by CS, BF, and SF (p < 0.5). A highly significant correlation existed between Ra and VW (p = 0.001, R 2 = 0.9803).

CONCLUSION

 The effect of TMC on the surface properties and wear resistance of the investigated TOV is material-dependent. GU injectable TOV are less influenced by TMC than CS milled TOV. In contrast, BF and SF demonstrated significant VW and Ra which might limit their clinical use as TOV.

Randomised controlled trial on testing an increased vertical dimension of occlusion prior to restorative treatment of tooth wear

BACKGROUND

Evaluation of a new vertical dimension of occlusion (VDO) in complex restorative treatments is considered a necessary step prior to placement of restorations.

OBJECTIVES

This randomised controlled trial (RCT) aimed to assess the effects of using an evaluation of a VDO increase before restorative treatment in patients with moderate-to-severe tooth wear, on OHRQoL, freeway space (FWS) and interventions to restorations.

METHODS

Forty-two patients with tooth wear were included and randomly allocated to either a test phase with a Removable Appliance (RA) or no test phase. Restorative treatment consisted of restoration of all teeth using composite restorations in an increased VDO. OHIP-score, freeway space (FWS) and clinical acceptability of restorations were assessed at baseline and at recall appointments (1 month and 1 year). Intervention to restoration was scored in case of material chipping or when the abutment tooth had increased sensitivity that could be linked to occlusal overloading. ANCOVA analyses, Univariate Cox regression, t-tests and descriptive analyses were performed (p < .05).

RESULTS

Clinical follow-up after 1 year was completed for 41 patients. No significant effect of testing the VDO with a RA could be found on the OHIP-score (p = .14). Reduction of FWS in the RA group, compared to the control group, was significantly lower at 1 year (p = .01, 95% CI -1.09 to -0.15). No effect on early interventions to restorations was found (p = .94).

CONCLUSION

This RCT showed that a removable appliance is not indicated to functionally test the increased VDO prior to restorative treatment in patients with tooth wear.

Indications for the use of direct composite restorations in the management of tooth wear

The increasing prevalence of tooth surface loss has been widely reported. Patients present with varying degrees of tooth wear and consideration is given to whether a prevention and monitoring approach, or a treatment and restoration approach, is appropriate. A missed diagnosis or excessively prolonged monitoring risks progression to the detriment of a successful outcome, with the potential compromise on the quality and quantity of tooth structure available for predictable adhesive dentistry. Direct composite resin (DCR) restorations can be considered as a viable treatment option for all extents of tooth wear, including cases that have progressed to a severe degree. This paper aims to review the indications for DCR restorations in the management of tooth wear, using clinical cases to demonstrate their effectiveness.

Sex-specific reference values for the crown heights of permanent anterior teeth and canines for assessing tooth wear

OBJECTIVE

We propose sex-specific reference values for the clinical crown height of anterior teeth and canines.

MATERIAL AND METHODS

In this cross-sectional study, 1426 teeth were analysed from 169 undergraduate and postgraduate dental students (83 women and 86 men, median age 22 years). Teeth with worn or totally restored incisal edges, or gingival inflammation were excluded. Age, gender and body height were recorded and the degree of tooth wear was scored according to the quantification module of the Tooth Wear Evaluation System. The clinical crown heights of all anterior teeth and canines were measured from the gingival margin to the incisal edge with a digital calliper. Reference values for tooth groups were obtained at the percentiles 10, and expressed by sex if there was a significant difference between men and women.

RESULTS

Mean crown heights were bigger in men than in women for each tooth group (p = .028). Clinical crown heights showed sexual dimorphism at the 10^th percentiles for all tooth groups except for mandibular anterior teeth.

CONCLUSIONS

For assessing tooth wear, the sex-specific reference values for the clinical crown height of young adults Caucasoids range from 7.5 mm to 9.0 mm in women and from 7.5 mm to 9.5 in men.

Application of Tribology Concept in Dental Composites Field: A Scoping Review

Tribology is the discipline concerning the application of friction, lubrication, and wear concepts of interacting surfaces in relative motion. A growing interest has developed in tribology application in medical biomaterials, such as resin composites used in restorative dentistry. Yet, the keywords "tribology" and "biotribology" are little applied in the pertinent publications. The aim of this scoping review was to offer an overview of tribology application in dental composites research and to identify knowledge gaps and address future research. A literature search was conducted on Pubmed and Scopus databases and the studies investigating the tribological behavior of resin composites were included for qualitative synthesis. The majority of studies on dental tribology were published in the research areas of mechanical engineering/nanotechnology and differed in several methodological aspects. The preponderant engineering approach and the lack of standardized testing make the laboratory findings poorly informative for clinicians. Future research should focus on the tribological behavior of dental materials composites by means of an integrated approach, i.e., engineering and clinical, for improving development and advancement in this field of research.

Wear Behavior between Aesthetic Restorative Materials and Bovine Tooth Enamel

Tooth enamel wear occurs because of daily mastication and occlusion. This study investigated the wear behavior of bovine teeth against aesthetic restorative materials in vitro. Abrader specimens were fabricated using four tooth-colored restorative materials (zirconia, lithium disilicate glass ceramic, dental porcelain, and resin composite), with bovine tooth enamel as a control. Flattened bovine tooth enamel was used as the substrate specimen. These materials were characterized by Vickers hardness tests and surface roughness measurements. Two-body wear tests between the abrader and substrate specimens were performed, and the worn topographies were evaluated using a contour-measuring instrument and 3D laser microscope. The restorative materials and bovine tooth enamel had similar surface roughness but different hardness and wear behaviors. Bovine teeth showed the largest wear in tooth–tooth contact as the abrader and substrate specimens. Compared to bovine teeth, zirconia, lithium disilicate glass ceramic, and dental porcelain showed greater hardness and less wear on their surfaces, and less substrate wear of the opposite tooth enamel. The lowest hardness resin composite showed intermediate wear on its surface, resulting in the lowest substrate wear. Accordingly, dentists should pay attention to the selection of restorative materials to reconstruct their morphologies owing to different wear behaviors.

Treatment of Tooth Wear Using Direct or Indirect Restorations: A Systematic Review of Clinical Studies

Tooth wear is considered a well-developed issue in daily clinical practice; however, there is no standard protocol for treatment. The aim of this manuscript was to systematically review the literature to evaluate the clinical outcomes of direct or indirect restorations for treating tooth wear. A literature search was conducted through the PubMed MedLine, Scopus, ISI Web of Science, Scielo, and EMBASE databases up to 29 April 2022. Clinical studies evaluating the clinical performance of direct or indirect restorations for treating tooth wear for a minimum follow-up of 6 months were included in the review. A total of 2776 records were obtained from the search databases. After full-text reading, 16 studies were included in the qualitative analysis. Considering the high heterogenicity of the studies included, a meta-analysis could not be performed. All studies included the rehabilitation of anterior and posterior teeth with extensive wear, using both indirect and direct restorations for a maximum follow-up of 10 years. Restoration materials included ceramo-metal crowns, full gold crowns, lithium disilicate ceramic, zirconia, polymer infiltrated ceramic networks, and resin composites. Most of the reports assessed the survival rate of the restorations and the clinical features using the United States Public Health Service (USPHS) Evaluation System criteria. Contradictory discoveries were perceived concerning the type of restoration with better clinical performance. Considering the current literature available, there is no evidence in the superiority of any restoration technique to ensure the highest clinical performance for treating tooth wear.

MicroCT evaluation for CAD/CAM occlusal veneer fit using two materials and three cement space settings

This study was aimed to evaluate the fit of occlusal veneer restoration for two CAD/CAM materials with different cement space settings, using microCT scans. Sixty resin dies were made and divided into two groups (n=30) according to the materials, (I): Hybrid all-ceramic, and (II): zirconia-reinforced lithium silicate glass-ceramic. Each group was subdivided into three subgroups (n=10) according to the cement space parameters (30, 40, and 50 µm). Occlusal veneers for the six subgroups were milled. A circle with 20 different sections was placed at the center of every scanned specimen to measure four different locations (Occlusal, Axial, Marginal, and Absolute marginal discrepancy). Data were analyzed using two-way ANOVA at a 0.05 level of significance. There was no statistically significant effect of material type on the mean values of internal and marginal gaps for the three cement space parameters (P>0.05). There were no statistically significant differences in the occlusal and axial gap between the cement space parameters, furthermore, there were statistically significant differences in marginal gap distances and absolute marginal discrepancies (P>0.05). Hybrid all-ceramic showed smaller marginal and internal discrepancies than zirconia-reinforced lithium silicate glass-ceramic without statistically significant differences, and, for both materials, 50 µm cement space significantly improved the marginal fit and absolute marginal discrepancy.

Prosthodontic Treatment in Patients with Temporomandibular Disorders and Orofacial Pain and/or Bruxism: A Review of the Literature

Temporomandibular disorders are a group of conditions affecting the temporomandibular joints, the jaw muscles, and related structures. Patients with temporomandibular signs and/or symptoms frequently present with indications for prosthetic treatment. The management of these patients aims to achieve patient comfort, occlusal stability, and the complex restoration of the teeth. The goal of this review is to provide an overview of the relationship between prosthodontics and temporomandibular disorders and/or bruxism with a focus on the cause-and-effect implications and the strategies for planning prosthetic treatments in patients with temporomandibular disorders and/or bruxism.

Rejuvenation of the ageing face and the role of orthodontics: Guidelines for management

The article reviews the ageing changes of the midfacial and maxillary bones, the mandible, the overlaying soft tissues and the smile, and presents clinical guidelines aiming to rejuvenate older faces by means of orthodontic therapy. With regard to the ageing changes, the maxillary skeleton appears to rotate clockwise inferior to the orbit and becomes retrusive, and as a general pattern the midface contracts and deteriorates with age. Resorption below the mental foramen, reduction in alveolar height, loss of bone at the chin region, and relative increase in size and shape are signs of an aged mandible. Epidermal thinning and decrease in collagen in combination with the effect of gravity and various external factors contribute to the ageing of the skin. Atrophy of the superficial and deep fat, changes in ligamentous tissues and changes in muscle structure, position and tone, all contribute to the stigmata of the aged face. In the article, two late adulthood orthodontic cases are discussed as examples, and general guidelines for orthodontic management of the older face aiming at reversing the 'shrinkage' of the tissues by restoring the facial shape and tightening the soft tissue mask are described. The possible mechanisms explaining the changes observed on the faces of the clinical cases are also discussed. A properly planned and executed orthodontic intervention reversing changes from the inside-out before embarking on cosmetic surgery might have a synergistic effect multiplying the benefits for adult patients.

Rehabilitation of Worn Dentition with Direct Resin Composite Restorations: A Case Report

The incidence of tooth wear has steadily increased in all Western populations during the past decades. A through-care strategy, extendable for a lifetime, has become crucial to prevent the extensive loss of sound dental structure and to make an eventual retreatment affordable in the long term. An interceptive treatment using resin composite materials and no-preparation approaches meets these requirements. Moreover, continual developments in digital dentistry makes possible to predict the treatment plan for the restorative rehabilitation of the mouth. The availability of digital resources allows clinicians to increase predictability for excellent esthetics and good functional results. This article provides a step-by-step description of a full-mouth additive rehabilitation achieved by employing digital workflows and direct resin composite restorations. A comprehensive functional and esthetic evaluation of the treatment is proposed and discussed.

Canine Rise Method: A Conservative Approach for Worn Teeth Rehabilitation with Different Adhesive Restorative Materials

Background

In this article, two cases with generalized dental wear and four cases with localized dental wear are reported. In some of the cases, the worn teeth were restored with direct composite techniques with no mock-up and articulator mounting according to the canine rise method. This method is used without any change in the intercuspation of posterior teeth without a muscle relaxation appliance. It introduces a stable occlusal condition that can alter neuromuscular reflex activity, leading to improvements in certain muscle pain disorders. It is also used to protect the teeth and supporting structures from abnormal forces that might create a further breakdown and/or tooth wear.

Methods

The first step of treatment in all the cases was a composite build-up for maxillary and mandibular canines to restrict and guide the horizontal and vertical jaw movements and create adequate space for restorations. The second step was the placement of direct or indirect restorations on upper and lower anterior teeth efficiently and accurately.

Results

This method enhanced the esthetic outcomes in a conservative approach with no reduction in tooth material or time-consuming treatments.

Conclusions

This technique can be suggested for the treatment of worn teeth in patients with Angle's Cl I and Cl II classifications of malocclusion based on the follow-up results. It is not applicable for the treatment of worn teeth in patients with Angle's class III because occlusion is reversed, and canine teeth do not have guidance role. Practical Implications. This method significantly reduces the overall treatment time, and additional steps are required to restore the worn-out teeth and/or occlusion using the canine rise method.

Survival Rates of Endodontically Treated Posterior Teeth Restored with All-Ceramic Partial-Coverage Crowns: When Systematic Review Fails

Background: To determine the survival rates of endodontically treated posterior teeth (EDPT) restored with partial coverage all-ceramic crowns with or without the use of fiber posts. Methods: MEDLINE and Cochrane searches were conducted in order to identify Randomized Clinical Trials (RCTs) related to endodontically treated posterior teeth restored with partial coverage crowns. The search period was extended until February 2020 and only in vivo, human, and studies in the English language were included. A manual search was also conducted and additional articles, if found, were included in the database. Results: The initial search for the selected databases identified 495 studies, which were all screened for inclusion through titles, abstracts and full-text reading. Out of these 495 studies, only one article met the eligibility criteria and was included in this systematic review. Statistical analysis could not be performed. Conclusions: Only one RCT was identified in this systematic review. More clinical evidence is necessary to assess the survival rate of EDPT with partial-coverage crowns. This systematic review failed because it did not find scientific evidence to support the use of indirect bonded restorations on EDPT.

Restorative difficulty evaluation system of endodontically treated teeth

OBJECTIVE

This article provides an updated overview of restorative procedures of endodontically treated teeth.

CLINICAL CONSIDERATIONS

The different techniques and procedures to restore an endodontic treated tooth were considered in the last decades. While they are generally performed using bonding procedures in combination with or without the placement of a post into the root to build up the abutment, there has been a lack of interest in restorative difficulties that can be faced. Failures are represented such as debonding of the post, fracture of the root, decementation, and/or fracture of the restoration, microleakage of the margins. Essentially, the presence of a sufficient failure is considered a key point of a long prognosis. Different clinical factors can directly influence the type of restoration and the longevity of the treatment. The restorative difficulty evaluation system (RDES) is proposed in this article. This new system is composed of eight different clinical factors that are divided into six levels of difficulties. The RDES is composed of 1. Endodontic complexity and outcome, 2. Vertical amount of coronal residual structure and dimension of the pulp chamber, 3. Horizontal amount of coronal residual structure, 4. Restoration marginal seal, 5. Local interdisciplinary conditions, 6. the complexity of the treatment planning, 7. Functional need, 8. Dental wear and esthetic need.

CONCLUSION

This article reviews the RDES and outlines critical steps and tips for clinical success.

CLINICAL SIGNIFICANCE

The RDES allows to any clinician to evaluate restorative difficulties when an endodontic treated tooth must be restored, combines clinical aspects that can involve from the single tooth to a full mouth rehabilitation.

Effect of Different Ceramic Materials on Fatigue Resistance and Stress Distribution in Upper Canines with Palatal Veneers

OBJECTIVE

 The aim of this study was to evaluate, by means of a fatigue life test, different ceramic materials used in palatal veneers to restore the canine guidance.

MATERIALS AND METHODS

 Forty-five standardized anatomical preparations were made in extracted healthy human canines with 1.2 uniform thickness. Samples were scanned, restorations were designed and milled in polymer-infiltrated ceramic network (PICN, Vita Enamic), zirconia-reinforced lithium silicate (ZLS, Vita Suprinity), and high translucent yttrium oxide-stabilized tetragonal zirconia (YZHT, Vita YZHT). Dental preparations were etched, restorations were processed according to the manufacturers' recommendations, and adhesively cemented. Then, three samples of each group were tested with load-to-fracture to determine the fatigue parameters. In addition, the palatal veneers stresses were evaluated using numerical models through finite element analysis.

RESULTS

 The mean of the monotonic test for PICN, ZLS, and YZHT was 674.18 N, 560.5 N, and 918.98 N, respectively. The StepWise test was performed until specimen fracture or until suspension of the test after 1.2 × 10⁶ cycles. Regarding survival, using the Kaplan-Meier method, PICN presented results for the mean and median of 245.21 N and 225 N, respectively; ZLS had an average of 175.76 N and a median of 168 N, and YZHT with an average of 383.30 N and a median of 366 N. Regarding the Weibull method, PICN showed results of 5.43 β and 264 η for form and scale, respectively; ZLS had 36.14 β for form and 380.67 η for scale; and YZHT presented 4.95 β for form and 417.38 η for scale. The highest stress value was calculated for YZHT, ZLS, and PICN, respectively.

CONCLUSIONS

 It was possible to conclude that all tested materials have the possibility of being used for rehabilitation of upper canines' palatal surface.

Effect of masseter muscle activity during wakefulness and sleep on tooth wear

PURPOSE

To investigate the effect of masseter muscle activity during wakefulness and sleep on tooth wear.

METHODS

Sixteen participants with no or mild tooth wear (NMTW group) and sixteen participants with moderate-to-severe tooth wear (MSTW group) were enrolled. The severity of tooth wear was evaluated using the occlusal and incisal indices of the tooth wear index. Surface electromyography was performed to record the electrical activity of the left masseter muscle during wakefulness and sleep. Electromyographic activity was detected using an electromyographic threshold of 5% and 20% of maximal voluntary clenching (MVC). The total duration of electromyographic activity and bruxism episodes were calculated.

RESULTS

The mean ages of the NMTW and MSTW groups were 71.75 ± 7.61 years and 71.69 ± 7.49 years, respectively. The mean cumulative duration of electromyographic activity during wakefulness using a threshold of >5% MVC was 6.44 ± 4.52 min/h and 13.62 ± 10.08 min/h for the NMTW and MSTW groups, respectively (p=0.048). The mean total durations of electromyographic activity during wakefulness and sleep using a threshold of >20% MVC were 1.08 ± 1.70 min/h and 1.05 ± 3.02 min/h, respectively, in the NMTW group and 4.78 ± 6.37 min/h and 1.61 ± 1.79 min/h, respectively, in the MSTW group (p=0.048 and p=0.003, respectively).

CONCLUSION

These results suggest that masseter electromyographic activity during wakefulness and sleep may be related to the severity of tooth wear.

Rehabilitation of a deep bite patient with worn dentition using minimally invasive approach: A 3-year follow-up

Full mouth rehabilitation of severely worn teeth represents a challenging situation for dental clinicians. This case report describes the minimally invasive interdisciplinary approach for treatment of severely worn dentition with a loss of vertical dimension of occlusion. After 3 years of follow-up, no complication was observed.

Fracture Resistance and Failure Mode of Mandibular Molar Restored by Occlusal Veneer: Effect of Material Type and Dental Bonding Surface

This study assesses the effect of the material type (lithium disilicate, zirconia, and polymer-infiltrated ceramic) and dental bonding substrates (dentin, dentin with intra-coronal cavity, and dentin with composite filling) on the fracture resistance and failure mode of molars restored by occlusal veneers. Methods: Ninety occlusal veneers, fabricated from either lithium disilicate, zirconia, or polymer-infiltrated ceramic, were adhesively bonded to teeth prepared with either dentin, dentin with intra-coronal cavity, or dentin with composite filling. All specimens were thermally aged (5000 cycles), then load cycled (120,000 cycles). Each specimen was subjected to a compressive load through fracture, then was examined (×20) to identify the fracture type. Data were statistically analyzed. Results: Material type and dental substrate had no significant effect on the fracture resistance of adhesively retained occlusal veneer restorations. For each material, no significant differences were found between veneers bonded to dentin, dentin with intra-coronal cavity, and dentin with composite filling. Additionally, within each bonding substrate, there were no significant differences between lithium disilicate, zirconia, and polymer-infiltrated ceramic veneers. The adhesive failure was recorded mainly with zirconia occlusal veneer restorations. Conclusions: Considering the fracture results, lithium disilicate, zirconia, and polymer-infiltrated ceramic occlusal veneers perform well whatever the type of dental bonding surface. When the dental bonding surface varies, different occlusal veneer materials should be considered. Occlusal veneers bonded to dentin, dentin with composite filling, or dentin with an intra-coronal cavity exhibited a fracture resistance exceeding the average human masticatory forces in the molar area.

Tooth Age Impact on Dental Erosion Susceptibility and Treatment Efficacy

This laboratory study investigated the impact of tooth age on dental erosion susceptibility and preventive treatment efficacy. Extracted human premolars were selected and had their age estimated (∼10-100 years old) using established dental forensic methods. Enamel and root dentin slabs were prepared, embedded in acrylic blocks, flattened, and polished. The specimens were randomly assigned to one of three treatments (n = 93): Sn+F (800 ppm Sn as SnCl2 and 250 ppm F as NaF, pH 4.5), NaF (250 ppm F, pH 4.5), or deionized water (DIW). Each specimen was subjected for 10 days to a daily cycling protocol consisting of six 5-min erosive challenges (0.3% citric acid, pH 2.6), six 60-min remineralization periods (artificial saliva), and three 2-min treatments with the test solutions. Surface loss (SL) was measured after 3, 5, and 10 days, using optical profilometry. Effects of tooth age, antierosive treatment, and time on SL were evaluated using linear mixed effects regression analysis. SL increased with age for all substrate-treatment-time combinations (p < 0.0001). Sn+F and NaF solutions significantly reduced SL compared to DIW, regardless of substrate, time, or age (p < 0.0001), with best results shown for Sn+F. Efficacy of Sn+F increased with tooth age on enamel, but tooth age did not affect the efficacy of NaF on enamel. For dentin, increased efficacy was observed with age after 5 (for Sn+F) and 10 days (for Sn+F and NaF). In conclusion, increase of tooth age rendered enamel and root dentin more susceptible to dental erosion. NaF preventive efficacy improved with tooth age for dentin, in advanced erosion simulation. Sn+F reduced enamel SL due to erosion regardless of tooth age.

Influence of Conventional, CAD-CAM, and 3D Printing Fabrication Techniques on the Marginal Integrity and Surface Roughness and Wear of Interim Crowns

The aim is to assess the influence of fabrication techniques—conventional (CN), CAD-CAM (CC), and 3D printing (3D)—on the marginal fit, adaptation, surface roughness, and wear of interim restorations of crowns. Thirty interim crowns were fabricated using CN, CC, and 3D techniques. Sixty discs were fabricated to evaluate surface wear and surface roughness properties, with 10 disc samples in each group (n = 10). Internal adaptation and marginal integrity of interim crowns were analyzed with micro CT to detect microgaps at selected points. Average surface micro-roughness (Ra) was calculated in micrometers (μm) using an optical non-contact surface microscope under cyclic loading. Surface wear was evaluated by surface area measurements (mm3) using a micro CT. Analysis of variance (ANOVA) and Tukey’s post hoc comparison tests with Pearson correlation were performed for data analysis. The highest adaptation means were for CN (269.94 ± 64 μm), and the lowest mean value was observed for 3D (197.82 ± 11.72 μm) crowns. CN and CC specimens showed comparable adaptation (p > 0.05), which were significantly higher (p < 0.05) than 3D crowns. CN crowns showed significantly higher marginal misfit compared to 3D (p < 0.05) and CC (p < 0.05) crowns. The highest mean surface roughness was observed in the 3D crowns (5.61 ± 0.33 µm), whereas the lowest was found in CC crowns (3.28 ± 0.34 µm). Better restoration Ra was observed using the CC method followed by CN. CN had the highest wear (17.79 ± 2.78 mm3), and the lowest wear was observed in the 3D (10.81 ± 2.00 mm3) specimen. Low surface wear was observed using 3D printing, followed by CN and CC techniques. The printed specimen showed comparable outcomes to CAD-CAM restoration; however, they were better than CN restoration. A positive correlation between adaptation and surface roughness was observed, indicating an effect of the fabrication technique on material physical property.

A Prosthodontic Approach as a Complementary Solution for a Complicated Orthodontic Treatment of a Patient with Cleidocranial Dysplasia

This clinical report describes a prosthodontic rehabilitation of a 29-year-old patient with cleidocranial dysplasia (CCD), who, after completing an orthodontic treatment, was not satisfied with the aesthetic outcome. Besides aesthetics, the patient complained about mastication muscles pain, and clicking while eating but was not aware about her unilateral open bite on the right side. The aim of this treatment was to improve smile appearance and patient's well-being, as well as to restore the proper occlusal vertical dimension (OVD) along with complete intercuspation and to establish masticatory function. The first phase of the treatment concentrated on eliminating the muscle pain and temporomandibular joint (TMJ) clicking with a repositioning splint. During the second phase, the functional and aesthetic rehabilitation was obtained using adhesive prosthesis overlays and veneers.

In-vivo-wear in composite and ceramic full mouth rehabilitations over 3 years

The aim of this study was to quantify and to compare the wear rates of premolar (PM) and molar (M) restorations of lithium disilicate ceramic (LS2) and an experimental CAD/CAM polymer (COMP) in cases of complex rehabilitations with changes in vertical dimension of occlusion (VDO). Twelve patients with severe tooth wear underwent prosthetic rehabilitation, restoring the VDO with antagonistic occlusal coverage restorations either out of LS2 (n = 6 patients, n = 16 posterior restorations/patient; N = 96 restorations/year) or COMP (n = 6 patients; n = 16 posterior restorations/patient; N = 96 restorations/year). Data was obtained by digitalization of plaster casts with a laboratory scanner at annual recalls (350 ± 86 days; 755 ± 92 days; 1102 ± 97 days). Each annual recall dataset of premolar and molar restorations (N = 192) was overlaid individually with the corresponding baseline dataset using an iterative best-fit method. Mean vertical loss of the occlusal contact areas (OCAs) was calculated for each restoration and recall time. For LS2 restorations, the mean wear rate per month over 1 year was 7.5 ± 3.4 μm (PM), 7.8 ± 2.0 μm (M), over 2 years 3.8 ± 1.6 µm (PM), 4.4 ± 1.5 µm (M), over 3 years 2.8 ± 1.3 µm (PM), 3.4 ± 1.7 µm (M). For COMP restorations, the mean wear rate per month over 1 year was 15.5 ± 8.9 μm (PM), 28.5 ± 20.2 μm (M), over 2 years 9.2 ± 5.9 µm (PM), 16.7 ± 14.9 µm (M), over 3 years 8.6 ± 5.3 µm (PM), 9.5 ± 8.0 µm (M). Three COMP restorations fractured after two years and therefore were not considered in the 3-year results. The wear rates in the LS2 group showed significant differences between premolars and molars restorations (p = 0.041; p = 0.023; p = 0.045). The wear rates in COMP group differed significantly between premolars and molars only in the first two years (p < 0.0001; p = 0.007). COMP restorations show much higher wear rates compared to LS2. The presented results suggest that with increasing time in situ, the monthly wear rates for both materials decreased over time. On the basis of this limited dataset, both LS2 and COMP restorations show reasonable clinical wear rates after 3 years follow-up. Wear of COMP restorations was higher, however prosthodontic treatment was less invasive. LS2 showed less wear, yet tooth preparation was necessary. Clinicians should balance well between necessary preparation invasiveness and long-term occlusal stability in patients with worn dentitions.

Clinical performance of direct composite resin restorations in a full mouth rehabilitation for patients with severe tooth wear: 5.5-year results

OBJECTIVES

To evaluate the 5.5-year performance of direct resin composite restorations, prescribed for patients with severe tooth wear, requiring full-mouth rehabilitation.

METHODS

A convenience sample of 34 patients were recruited to a prospective trial between December 2010 and June 2013. The participants were provided 1269 full-mouth direct resin composite restorations (Clearfil AP-X) by 5 experienced operators, using the DSO-technique. Treatment resulted in an increase in the vertical dimension of occlusion (VDO). Failure was assessed at three levels. Frequencies of failure were analysed using Kaplan Meier survival curves and the effects of the relevant variables calculated with a multifactorial Cox regression (p < 0.05).

RESULTS

Annual failure rates (for all levels of failure, 'Level 3- ') of ≤ 2.2% and ≤ 2.9% were respectively reported for the anterior and posterior restorations with a mean observation time of 62.4 months. The completion of an anterior restoration with the need for further appointments resulted in significantly more Level 2- & 3- failures. An evaluation of the performance of the premolar and posterior maxillary restorations showed significantly lowered risks of certain types of failures, compared to the molar and posterior mandibular restorations.

CONCLUSIONS

At 5.5 years, 2.3% of the overall restorations displayed catastrophic, (Level 1) failures. Molar restorations, posterior mandibular restorations and the anterior restorations requiring two further sessions for completion, were associated with significantly higher risks for failure.

CLINICAL SIGNIFICANCE

Direct resin composite can offer an acceptable medium-term option for the treatment of severe, generalized tooth wear; molar restorations may require higher maintenance.

The effect of pre-treatment levels of tooth wear and the applied increase in the vertical dimension of occlusion (VDO) on the survival of direct resin composite restorations

OBJECTIVES

To investigate the effects of the level of pre-treatment tooth wear and increasing the VDO on the performance of direct resin composite restorations for the rehabilitation of pathological tooth wear.

METHODS

Full-mouth (pre-treatment) grading was performed on digital greyscale scan records for 34 participants (35.3 ± 8.4 years) with signs of moderate-to-severe generalised tooth wear, using the Tooth Wear Evaluation System and the Basic Erosive Wear Examination. Each participant received full-mouth direct resin composite restorations, with increased VDO. The post-treatment increase in the VDO was determined. Recalls were planned after 1 month, and after 1, 3, and 5 years. Three 'levels' of restoration failure were described. The effects of the variables on the frequencies of restoration failure were calculated with a multivariable Cox regression, (p < 0.05).

RESULTS

1269 restorations were placed with a mean observation period of 62.4 months. Increasing the VDO by 1 mm significantly reduced the risks of all levels of anterior restoration failure (HR ≤ 0.62, p ≤ 0.025). A higher anterior BEWE surface score was associated with increased risks of Level 2- & 3- failures, (HR ≥ 1.29, p ≤ 0.019). Premolar restorations showed lower risks of Level 2- & 3- failure, compared to the molar restorations, (HR ≤ 0.5, p ≤ 0.005).

CONCLUSION

Levels of pre-treatment wear and the applied change in the VDO significantly affected failure risk.

CLINICAL RELEVANCE

Direct resin composite restorations for the rehabilitation of wear should be made as voluminous as possible, respecting the presenting biological, functional, and esthetic constraints.

Occlusal Vertical Dimension: Best Evidence Consensus Statement

PURPOSE

Patients in need of extensive prosthodontic treatment may need restoration of their occlusal vertical dimension (OVD) due to tooth wear, tooth loss, or changes that have occurred to existing prostheses over time. Prosthodontic treatment is based on the clinical application of the available evidence regarding interocclusal distance (IOD), the positional stability of rest vertical dimension (RVD), and the effect of altering the OVD. Hence, the purpose of this consensus document is to examine available data related to IOD, RVD, and alteration of the OVD.

MATERIALS AND METHODS

The search was limited to Clinical trials, Randomized Controlled Trials, Systematic Reviews and Meta-analyses. Key words were healthy patient, mean, range, interocclusal rest distance; healthy patient, mean, range, freeway space; and dentistry, interocclusal gap, and no citations appeared. Dentistry, interocclusal distance, revealed 5 not relevant citations. Dentistry, inter occlusal rest space, and dentistry, interocclusal rest distance, both had the same single not relevant citation. Dentistry, freeway space revealed over 7,000 citations. Dentistry, occlusal vertical dimension, revealed 253 citations, 7 of which were related to the search question but only 1 which was different from the previous search. Mandible, rest vertical dimension, age changes, found 7 citations, none relative to the question. Expanding the search to include journal article found 260 citations with only one relevant to the question. Mandible, rest vertical dimension, alteration, harm revealed no citations; mandible, occlusal vertical dimension, alteration, revealed 15 citations, 1 of which was relevant; mandible, occlusal vertical dimension, changes, revealed 75 citations, none of which were relevant; mandible, occlusal vertical dimension, rehabilitation revealed 10 citations, none of which were relevant. Expanding the search strategy to include Journal article, mandible, occlusal vertical dimension, alteration, received 159 citations, 4 of which were relevant; mandible, occlusal vertical dimension, restoration revealed 208 citations, 1 of which was relevant. Numerous other articles were culled by going through the reference lists of the aforementioned articles.

RESULTS

For IOD, 27 articles were found relevant to the search question, which confirmed a mean of 3.0 mm with ranges from 1 to 9 mm. Five articles revealed little evidence as to whether the RVD changes during life. For OVD, 20 articles, including 4 systematic reviews, revealed some evidence that skeletal growth continues from mid adolescence into mid adulthood; strong anecdotal evidence that some unopposed teeth will continue to erupt; no clinical evidence to support the concept that abraded teeth in occlusion in a patient with bruxism will undergo continuous eruption; and some evidence from clinical case reports that restoring OVD in patients with severe abrasion is a successful treatment.

CONCLUSIONS

There is a range of dimensions for the interocclusal distance (IOD) with many normal dental patients functioning with a higher or lower IOD than the commonly used 3.0 mm average dimension. The resting vertical dimension (RVD) is a 3-dimensional range with little evidence related to changes in the RVD during life. However, aging can cause a decrease in muscle tone which could affect the RVD. The restoration of the OVD can be successfully accomplished if proper diagnosis and treatment planning are performed.

Direct Composite Resin for the Management of Tooth Wear: A Systematic Review

BACKGROUND

This study systematically reviewed survival of direct composite to restore worn teeth.

MATERIALS AND METHODS

A comprehensive electronic search of databases sourced from Medline-PubMed, Embase, Cochrane Central, Scopus, Google scholar was performed on literature published between January 1990 and December 2018. Grey literature was also reviewed. Data extraction included sample size, number of composite restorations, operators, composite type, mean or total follow-up time and success rate expressed as either percent of successful restorations or median survival time (MST). Methodological quality was rated using the Joanna Briggs Institute appraisal checklist for case series. Studies on children, non-carious cervical lesions, cast and all-ceramic restorations, case reports and case series with <5 participants were excluded.

RESULTS

A total of 1563 studies were identified and 1472 were screened. Sixty-two full-text papers were assessed for eligibility which resulted in 10 studies that met inclusion criteria. These were mainly case series and assessed 3844 direct composite restorations placed in 373 patients mostly in hospital settings. Survival ranged from 50% to 99.3%. Methodological quality improved from the earlier studies and was rated low to moderate in 7 studies and good in 3. The funnel plot showed a low risk of publication bias but there was considerable heterogeneity (I²=97.7%). There was a non-significant weak negative association between age and survival (Spearman's rho=-0.12).

CONCLUSION

Qualitative evaluation of the studies proved difficult because of the nature of case series but reporting improved in the later studies. Despite the generally short duration of studies, small sample sizes in terms of patient numbers and composite restorations, the survival rates of direct hybrid composite resin in the short to medium term are acceptable and support their application for the restoration of worn teeth.

Oral rehabilitation following successful TMD treatment with condylar position changes: A case report

BACKGROUND

A 31-year-old woman with crowns, fixed partial prostheses, and dental restorations complained of recurrent pain in the left and right temporomandibular joints during the last 2 years.

CLINICAL PRESENTATION

The symptoms of temporomandibular disorder (TMD) resolved successfully after a 3-month-long treatment with a repositioning splint. Pre- and post-operative cone-beam computed tomography revealed slight changes in the condylar position after splint use. Minimally invasive oral rehabilitation guided by digital design was performed to maintain the acquired stable position. The status of the restorations was good, and the TMD symptoms did not relapse during the 3-year follow-up.

CONCLUSION

This case report demonstrates the importance of a stable adapted condylar position after extensive prosthodontic treatment.

Load-bearing capacity of CAD/CAM 3D-printed zirconia, CAD/CAM milled zirconia, and heat-pressed lithium disilicate ultra-thin occlusal veneers on molars

OBJECTIVES

The load-bearing capacity of ultra-thin occlusal veneers made of 3D-printed zirconia were compared to the ones obtained by fabricating these reconstructions by CAD/CAM milling zirconia or heat-pressing lithium-disilicate.

METHODS

On 60 extracted human molars, the occlusal enamel was removed and extended into dentin. Occlusal veneers of 0.5 mm thickness were digitally designed. The specimens were divided into 3 groups (n = 20 each) differing in the restorative material and the fabrication technique of the occlusal veneer. (1) 3DP: 3D-printed zirconia (Lithoz); (2): CAM: milled zirconia (Ceramill Zolid FX); (3) HPR: heat-pressed lithium disilicate (IPS e.max Press). After conditioning procedures, the restorations were adhesively bonded onto the conditioned tooth. Thereafter, all specimens were aged in a chewing simulator by exposure to cyclic fatigue and temperature variations. Subsequently the specimens were statically loaded and the load which was necessary to decrease the maximum load by 20% and initiate a crack (F_initial) and the load which was needed to fracture the specimen (F_max) were measured. Differences between the groups were compared applying the Kruskal-Wallis (KW) test and the Wilcoxon-Mann-Whitney-Test (WMW: p < 0.05).

RESULTS

The median F_initial values for the groups 3DP, CAM and HPR were 1'650 N, 1'250 N and 500 N. The differences between all three groups were statistically significant (KW: p < 0.0001). The median F_max values amounted to 2'026 N for the group 3DP, 1'500 N for the group CAM and 1'555 N for the group HPR. Significant differences were found between 3DP and CAM (WMW: p = 0.0238).

SIGNIFICANCE

Regarding their load-bearing capacity, 3D-printed or milled zirconia as well as heat-pressed lithium disilicate can be recommended as restorative material for ultra-thin occlusal veneers to prosthetically compensate for occlusal tooth wear. Despite statistically significant differences between the restoration materials, all load-bearing capacities exceeded the clinically expected normal bite forces.

Load-bearing capacities of ultra-thin occlusal veneers bonded to dentin

OBJECTIVES

To test whether the load-bearing capacity of occlusal veneers made of ceramic or hybrid materials bonded to dentin does differ from those of porcelain-fused-to metal or lithium disilicate glass ceramic crowns.

MATERIAL AND METHODS

In 80 human molars, occlusal tooth substance was removed so that the defects extended into dentin, simulating defects caused by attrition/erosion. Restorations at a standardized thickness of either 0.5 mm or 1.0 mm were digitally designed. For both thicknesses, 4 test groups (n = 10 per group) were defined, each including a different restorative material: "0.5-ZIR": 0.5 mm thick zirconia (Vita YZ HT); "1.0-ZIR": 1.0 mm thick zirconia (Vita YZ HT); "0.5-LDC": 0.5 mm thick lithium disilicate ceramic (IPS e.max Press); "1.0-LDC": 1.0 mm thick lithium disilicate ceramic (IPS e.max Press); "0.5-HYC": 0.5 mm thick PICN (Vita Enamic); "1.0-HYC": 1.0 mm thick PICN (Vita Enamic); "0.5-COC": 0.5 mm thick tooth shaded resin composite (Lava Ultimate) and "1.0-COC": 1.0 mm thick tooth shaded resin composite (Lava Ultimate). Consecutively, the specimens were thermo-mechanically aged and then loaded until fracture. The load-bearing capacities (F_max) between the groups were statistically compared using the Kruskal-Wallis test (p < 0.05) and pairwise group comparison applying the Dunn's method. In addition, the results were compared to those of conventional lithium-disilicate ceramic crowns ("CLD") and to porcelain-fused to metal crowns ("PFM").

RESULTS

The median F_initial values for the 0.5 mm thin restorations were 1'350 N for 0.5-ZIR, 850 N for 0.5-LDC, 1'100 N for 0.5-HYC and 1'950 N for 0.5-COC. With CLD as the control, a significant difference was found between the groups 0.5-COC and 0.5-LDC (KW: p = 0.0124). With PFM as the control, the comparisons between PFM and 0.5-LDC as well as between 0.5-COC and 0.5-LDC were significant (KW: p = 0.0026). Median F_max values of 2'493 N in the group 0.5-ZIR, 1'165 in the group 0.5-LDC, 2'275 N in the group 0.5-HYC and 2'265 N in the group 0.5-COC were found. The medians of the F_initial values for the 1.0 thick restorations amounted of 2'100 N in 1.0-ZIR, 1'750 N in 1.0-LDC, 2'000 N in 1.0-HYC and 2'300 N in 1.0-COC. Testing the multiple comparisons with Dunn's method no significant differences were found (p > 0.05). The median F_max values of the 1.0 mm thick restorations were: 2'489 N in the group 1.0-ZIR, 1'864 N in the group 1.0-LDC, 2'485 N in the group 1.0-HYC and 2'479 N in the group 1.0-COC. With CLD as the control group, a significant difference between zirconia and lithium-disilicate was found for the 0.5 (p = 0.0017) and 1.0 mm (p = 0.0320) thick specimens. Comparing the 0.5 mm thick specimens with CLD as the control, a significant difference was found between 0.5-HYC and 0.5-LDC (p = 0.0017). With PFM as the control, the comparison of lithium disilicate and zirconia was statistically significant for both thicknesses (p = 0.0009 for the 0.5 mm thick specimens; p = 0.0074 for the 1.0 mm thick specimens). In addition, with PFM as control group, significant differences were seen between 0.5-LDC and all other groups with restorations in 0.5 mm thickness (p = 0.0017).

CONCLUSIONS

Regarding their maximum load-bearing capacity, minimally invasive occlusal veneers made of ceramic, hybrid materials or polymeric materials can be applied to correct occlusal tooth wear with exposed dentin and thus replace conventional crown restorations in cases of normally expected intraoral bite forces.

Zerumbone from Zingiber zerumbet (L.) smith: a potential prophylactic and therapeutic agent against the cariogenic bacterium Streptococcus mutans

BACKGROUND

Essential oil obtained from rhizomes of the Zingiber zerumbet (L.) Smith (popularly known in Brazil as bitter ginger) is mainly constituted by the biomolecule zerumbone, which exhibit untapped antimicrobial potential. The aim of this study was to investigate the antimicrobial activity of the zerumbone from bitter ginger rhizomes against the cariogenic agent Streptococcus mutans.

METHODS

Firstly, the essential oil from rhizomes of Zingiber zerumbet (L.) Smith extracted by hydrodistillation was submitted to purification and recrystallization process to obtain the zerumbone compound. The purity of zerumbone was determined through high-performance liquid chromatography analysis. Different concentrations of zerumbone were tested against the standard strain S. mutans (ATCC 35668) by using microdilution method. The speed of cidal activity was determined through a time kill-curve assay. The biological cytotoxicity activity of zerumbone was assessed using Vero cell line through MTT assay.

RESULTS

The zerumbone showed a minimum inhibitory concentration (MIC) of 250 μg/mL and a minimum bactericidal concentration (MBC) of 500 μg/mL against S. mutans. After six hours of bacteria-zerumbone interaction, all concentrations tested starts to kill the bacteria and all bacteria were killed between 48 and 72 h period at the concentration of 500 μg/mL (99,99% of bacteria were killed in comparison with original inoculum). In addition, zerumbone showed no cytotoxicity activity on mammalian continuous cells line.

CONCLUSIONS

These results draw attention to the potential of zerumbone as antimicrobial agent against S. mutans infection, indicating its possible use in the phyto-pharmaceutical formulations as new approach to prevent and treat tooth decay disease.

Ultra-thin occlusal veneers bonded to enamel and made of ceramic or hybrid materials exhibit load-bearing capacities not different from conventional restorations

OBJECTIVES

The objective of this study was to test whether or not the load-bearing capacity of occlusal veneers bonded to enamel and made of ceramic or hybrid materials does differ from those of porcelain-fused-to-metal or lithium disilicate glass ceramic crowns.

MATERIAL AND METHODS

In 80 human molars occlusal enamel was removed without extending into the dentin in order to mimic substance defects caused by attrition. The restorations were digitally designed at a standardized thickness of either 0.5 mm or 1.0 mm. For each thickness, 4 test groups were formed each including a different restorative material: "0.5-ZIR": 0.5 mm thick zirconia (Vita YZ HT); "1.0-ZIR": 1.0 mm thick zirconia (Vita YZ HT); "0.5-LDC": 0.5 mm thick lithium disilicate ceramic (IPS e.max Press); "1.0-LDC": 1.0 mm thick lithium disilicate ceramic (IPS e.max Press); "0.5-HYC": 0.5 mm thick PICN (Vita Enamic); "1.0-HYC": 1.0 mm thick PICN (Vita Enamic); "0.5-COC": 0.5 mm thick tooth shaded resin composite (Lava Ultimate) and "1.0-COC": 1.0 mm thick tooth shaded resin composite (Lava ultimate). Each group consists of 10 specimens. Two additional groups of 10 specimens each were used as controls and exhibited conventional crown preparations. In one group the crowns were made of lithium-disilicate ceramic ("CLD": IPS e.max CAD) and the other group consisted of porcelain-fused to metal crowns ("PFM"). All restorations were cemented onto the prepared teeth following the manufacturer's instruction of the corresponding luting cement. Subsequently, they were thermo-mechanically aged and then loaded until fracture. Load-bearing capacities (F_max) between the groups were compared applying the Kruskal-Wallis test (p < 0.05) and pairwise group comparisons using the Dunn's method.

RESULTS

Median values (and quartiles) for the load-bearing capacity amounted to (F_max) 2'407 (1'670; 2'490) N for the CLD group and to 2'033 (1'869; 2'445) N for the PFM group. For the 0.5 mm thick restorations F_max reached the highest median value in group 0.5-HYC 2'390 (1'355; 2'490) N, followed by 0.5-COC 2'200 (1'217; 2'492) N and 0.5-LDC 1'692 (1'324; 2'355) N. No results were obtained for group 0.5-ZIR due to the impracticability to fabricate ultra-thin specimens. The distribution of the values for the 1.0 mm thick restorations was 2'489 (2'426; 2'491) N for 1.0-COC, 2'299 (2'156; 2'490) N for 1.0-ZIR, 2'124 (1'245; 2'491) N for 1.0-HYC, and 1'537 (1'245; 1'783) N for 1.0-LDC. The differences of the medians between the test and the control groups did not reach statistical significance for the 0.5 mm thick specimens (KW: p = 0.6952 and p = 0.6986). Within the groups exhibiting 1.0 mm thickness, however, significant different medians were found: 1.0-LDC < 1.0-ZIR and 1.0-LDC < 1.0-COC (KW: p < 0.0209).

CONCLUSIONS

Regarding their maximum load-bearing capacity, minimally invasive occlusal veneers made of ceramic and hybrid materials can be applied to correct occlusal tooth wear and thus replace conventional crown restorations.

Complete rehabilitation of compromised full dentitions with adhesively bonded all-ceramic single-tooth restorations: Long-term outcome in patients with and without amelogenesis imperfecta

OBJECTIVES

This clinical follow-up evaluated the long-term outcome of full-mouth rehabilitations with adhesively bonded all-ceramic restorations in patients suffering from amelogenesis imperfecta (AI) or affected by extensive tooth wear including a loss of the vertical dimension of occlusion.

MATERIALS AND METHODS

Included for evaluation were all patients treated with adhesively bonded monolithic single-tooth restorations made of silicate or lithium disilicate ceramics; allowing a maximum four missing teeth and a facial feldspathic veneering of LDS anterior crowns. After treatment, patients have been enrolled in a recall program for dental check-ups including quality assessment of the restorations. Patients answered the oral health impact profile (OHIP-14) at their last visit.

RESULTS

Seventeen patients (mean age = 35 ± 18 years) were observed up to 16.5 years (mean: 6.2 ± 3.8 years). 12 out of 450 restorations failed due to core fracture (n = 7), tooth fracture (n = 2), one secondary caries, one chip-off grade 3, and one fixed dental prosthesis due to discomfort. The overall mean survival rate of the single-tooth restorations was estimated 99.4% at 5 and 91.4% at 10 years. The overall mean success rate was estimated 92.6% at 5 and 81.4% at 10 years, mainly due to chip-offs and crack formation (27 out of 31 relative failures). The mean annual failure rates (AFR) range between 1.5 and 2% over the years, but non-AI patients were affected more frequently by early technical complications in the facial veneering of anteriors, resulting in an AFR ranging between 5.2 and 4%. Quality assessment revealed stable color, form and marginal integrity in all patients up to ten years. The distribution of OHIP values is comparable to the representative sample of healthy patients.

CONCLUSION

Adhesively bonded single-tooth restorations provided a high clinical quality in the long-run. However, while the survival and success were excellent in AI patients, restorations in non-AI patients were affected by a higher complication rate, likely related to a higher risk profile due to a history of bruxism and tooth wear.

The Protocol of Fixed Reconstruction for Severely Worn Teeth Combined with Anterior Deep Bite

Full mouth reconstruction is one of the most effective methods to restore severe worn teeth that have suffered reduced vertical dimension. Although the use of the overlay splint restoration for a trial period allowing the patient to adapt to an increased vertical dimension is the recognized method, the specific protocol from the transitional splint to the fixed reconstruction is yet to be established. This case report describes a 50-year-old female patient who has severely worn teeth combined with an anterior deep bite and chewing pain. The protocol of the treatment process is described.

Worn is born: The role of the maxillo-mandibular relation in management of worn dentition

Worn dentition, often accompanied by occlusion changes such as reduced vertical dimension, poses a big challenge to both diagnosis and treatment. Current established causes fail to explain the observed tooth wearing patterns, and the treatments based on the documented pathogeneses are often unpredictable and require frequent maintenance. From the perspective of stomatognathic system, we postulate that the role of maxillo-mandibular relation is a crucial part in the tooth wear progression patterns, and should be well addressed in treatment planning. Incompatible occlusion with the inherent tendency of maxillo-mandibular relation has a profound effect on either wearing of natural teeth or failures of restorations. With the aid of cephalometrics and analysis of occlusion it is now possible to reduce this fallacy and achieve a harmony by re-designing the occlusion. According to our treated worn dentition cases, the restoring treatment guided by the tendency of maxillo-mandibular relation showed very promising results.

Restoration of the Occlusal Vertical Dimension with an Overlay Removable Partial Denture: A Clinical Report

The process of tooth loss throughout life associated with severe occlusal wear may pose a challenge in the rehabilitation of partially edentulous arches. In these cases, many therapeutic procedures are necessary because each tooth must be restored to obtain the correct anatomical contour and recover the occlusal vertical dimension (OVD). A removable partial denture (RPD) with occlusal/incisal coverage, also known as an overlay RPD, is an alternative treatment option with fewer interventions, and, consequently, lower cost. This clinical report reviews the principles involved in the clinical indication for an overlay RPD, as well as the necessary planning and execution, to discuss the feasibility and clinical effectiveness of this treatment, identifying the indications, advantages, and disadvantages of this procedure through the presentation of a clinical case. The overlay RPD can be an alternative treatment for special situations involving partially edentulous arches in patients who need reestablishment of the OVD and/or realignment of the occlusal plane, and it can be used as a temporary or definitive treatment. The main advantages of this type of treatment are its simplicity, reversibility, and relatively low cost; however, further studies are needed to ensure the efficacy of this treatment option.

Esthetic Rehabilitation through Crown Lengthening Surgery and Conservative CAD/CAM Veneers: A Multidisciplinary Case Report

This case report describes a successful multidisciplinary approach used to improve the smile esthetics of a patient presenting with excessive gingival display, asymmetric gingival margins, and small upper anterior teeth and lower anterior teeth. The treatment combined esthetic crown lengthening, dental bleaching, and restorative dentistry using CAD/CAM veneer. The 6-month follow-up examination confirmed the stability of the modification and absence of adverse effects.