Analyzing the etiology of an extremely worn dentition

Advanced Adhesive Approach to Support a Minimally Invasive Full Mouth Rehabilitation

OBJECTIVE

Patients who exhibit severe loss of tooth structure are challenging to rehabilitate. Conventional treatment of these patients may require adjunctive procedures of surgical crown lengthening, elective endodontic therapy and placement of posts and cores to retain full coverage crowns as part of a full mouth rehabilitation. Minimally invasive approaches to treatment of these patients provides opportunity to conserve tooth structure and to reduce adjunctive procedures by using an advanced adhesive approach to retain all ceramic partial coverage restorations as part of a full mouth rehabilitation.

CLINICAL CONSIDERATIONS

The use of an advanced adhesive approach to perform a full mouth reconstruction restoring occlusal vertical dimension (OVD) is described. This approach emphasizes preserving healthy tooth structure, maximizing restoration adhesion to enamel and dentin, maintaining pulpal vitality and minimizing adjunctive dental procedures. The preparation design focuses on being defect-oriented to remove only diseased or undermined tooth structure. The all ceramic restorations are additive, where indicated, to further aid in preserving tooth structure. An advanced adhesive approach using an immediate dentin seal and resin coating over exposed dentin and composite resin cement under rubber dam isolation is used to lute the restorations. The restorations are fabricated using micro-layered lithium disilicate ceramic to maximize the esthetic appearance of the rehabilitation where needed.

CONCLUSION

An advanced adhesive approach to full mouth rehabilitation should be considered as a treatment option for patients exhibiting tooth surface loss as an alternative to conventional full coverage restorations when clinical parameters allow.

Diagnostic accuracy of clinical signs to detect erosive tooth wear in its early phase

BACKGROUND

Agreement exists about most of the clinical features of erosive tooth wear, though no evidence supports their validity in diagnosing the condition.

OBJECTIVE

This study aimed to determine the accuracy of clinical signs for diagnosing erosive tooth wear in a young adult general population.

METHODS

We conducted a cross-sectional study of dental students. In the first session, two examiners independently determined the presence of erosive tooth wear based on glazed enamel surfaces, morphological changes on non-occlusal surfaces, flattening of convex areas, or any type of concavity. In the second session, one examiner recorded the presence of clinical signs according to the Tooth Wear Evaluation System. The diagnostic accuracy of each clinical sign, both alone and combined, was assessed by calculating their sensitivity and specificity for detecting erosive tooth wear and performing multivariate logistic regression models.

RESULTS

Of the 147 participants (78 women and 69 men; median age, 22 years) we included, 76.2% had erosive tooth wear. The single clinical signs with greatest balance between the sensitivity and specificity were 'convex areas flatten' (63% and 71%, respectively) and 'dull surface' (47% and 89%, respectively). Multivariate logistic regression revealed that 'preservation of the enamel cuff' (odds ratio, 22) and the combination of 'smooth silky shining, silky glazed appearance, and dull surface' (odds ratio, 68) had the best predictive values.

CONCLUSIONS

The most accurate clinical signs for detecting early erosive tooth wear were dull surface, flattened convex areas and preservation of the enamel cuff.

Sleep bruxism: The past, the present, and the future-evolution of a concept

BACKGROUND

The concept of sleep bruxism (SB) has evolved exponentially over the past several decades. Many theories and hypotheses have been proposed as to the definition, pathophysiology, and management of SB, from the early 1960s through the present. The role of peripheral factors, such as dental occlusion, in the pathogenesis of SB has been discarded.

TYPES OF STUDIES REVIEWED

The authors searched several electronic databases (ie, PubMed, Google Scholar, Web of Science, Embase, and Ovid MEDLINE) for studies on bruxism. The search was conducted from January 1961 through May 2023 and yielded 4,612 articles, of which 312 were selected for comprehensive review after eliminating duplicates and nonfocused articles.

RESULTS

There has been an evident progressive shift from the role of peripheral factors, such as dental occlusion, to more central factors, such as the involvement of a central pattern generator as well as the autonomic nervous system, in the genesis of bruxing movements. There is continued robust interest in the dental community to elucidate the contributing factors involved in SB.

CONCLUSIONS AND PRACTICAL IMPLICATIONS

The neurophysiology of SB appears to be leaning more toward central rather than peripheral factors. There is increasing evidence of the role of the autonomic nervous system, genetics, and comorbidities in the genesis of SB. The scientific literature seems to refute the role of dental occlusion in the causation of bruxing movements. As per the literature, there has been a paradigm shift in the definition and genesis of SB and its possible dental implications and management, which also highlights the need for succinct scientific studies in this regard.

Relationship between Pathological Occlusal Changes and the Signs and Symptoms of Temporomandibular Dysfunction

Objective

This study aimed to investigate whether there is a correlation between pathological occlusal changes and the signs and symptoms of temporomandibular dysfunction (TMD).

Methods

This cross-sectional, quantitative, non-randomized clinical trial was conducted on 150 participants. We examined adult patients of both genders with occlusal interference, malocclusion and dental absence in the posterior region of the dental arch that were associated or not associated with painful symptoms. The questionnaire was administered, and the intra- and extra-oral clinical examination was performed on each patient, including the evaluation of the temporomandibular joint (TMJ) to investigate the presence of dysfunction.

Results

The mean age of the participants was 33 years (±2.3), and 103 (68.7%) of them were women and 47 (31.3%) were men. Tooth loss and malocclusion were more prevalent in females. Tooth loss showed a statistically significant association with all the signs and symptoms of TMD (p=0.02). Patients with multiple teeth losses experienced preauricular pain during mandibular opening and closing. There was no association between malocclusion with tooth loss and the signs and symptoms of TMD in 65 patients (p>0.05).

Conclusion

Only in the patients with Class II malocclusion there was a significant association with 2 signs of TMD (crackling and bruxism). There was no association between malocclusion and tooth loss with the signs and symptoms of TMD. The signs and symptoms of TMD were more frequent in the patients who presented multiple teeth loss without malocclusion.

Clinical presentation of two phenotypes of tooth wear patients

OBJECTIVE

To assess the clinical presentation of wear lesions in two phenotypes of tooth wear (TW) patients based on distribution and morphological features of wear.

MATERIALS AND METHODS

103 patients (mean age = 43.1 years) were divided into two groups based on cluster analysis; cluster A (61 patients) and cluster B (42 patients). The distribution of wear lesions, scores of presence or absence of 10 defined morphological TW criteria and number of teeth fulfilling each criteria were compared between groups. Intra- and inter-examiner reliability of the 10 TW criteria was determined by Cohen's kappa and intraclass correlation coefficient.

RESULTS

While cluster A had more wear in maxillary anterior teeth and mandibular molars compared with the same opposing tooth groups (p < 0.001, p < 0.007 respectively), there were no differences for cluster B. Cluster A was characterized by higher prevalence of 4 chemical morphological criteria and the highest number of teeth affected by one chemical criteria, whereas cluster B had a higher prevalence of one mechanical criteria and higher number of teeth affected by an additional mechanical criteria. Both intra- and inter-examiner values for the defined TW criteria were fair to excellent.

CONCLUSION

The results may indicate a more chemical background for TW in cluster A and mechanical background in cluster B. Furthermore, clinicians may use certain clinical features of TW to distinguish between individuals who belong to a specific TW cluster with a presumed chemical or mechanical etiology. These preliminary findings need to be confirmed in future studies.

Cup-Shaped Tooth Wear Defects: More than Erosive Challenges?

BACKGROUND/AIM

The underlying mechanism of the development of cups and grooves on occlusal tooth surfaces is still unclear. The aim of this study was to evaluate factors contributing to in vitro cup formation, in order to elucidate the clinical process.

METHODS

A total of 48 extracted human molar teeth were exposed to acidic aqueous solutions at pH of 4.8 and 5.5 in constant motion, in combination with different loading conditions: no load (0N group, control), 30 N (30N group) or 50 N (50N group) (n = 8 per group). Before and after 3 months of exposure (1,422,000 loading cycles), the samples were scanned using a non-contact profilometer. Pre- and post-exposure scans were subtracted and height loss and volume tissue loss were calculated. Representative samples with wear and cupping lesions were imaged using scanning electron microscopy, light microscopy and micro-computed tomography.

RESULTS

Average height and volume tissue loss at pH 5.5 was 54 µm and 3.4 mm3 (0N), 52 µm and 3.4 mm3 (30N) and 58 µm and 3.7 mm3 (50N), respectively, with no statistically significant differences. Average height and volume loss at pH 4.8 were 135 µm and 8.7 mm3 (0N), 172 µm and 12.6 mm3 (30N) and 266 µm and 17.8 mm3 (50N), respectively, with a statistically significant difference between 0N and 50N (p < 0.002). Cup-shaped lesions had formed only at pH of 4.8, in the 30N and 50N groups.

CONCLUSION

The study showed that a cup can arise fully in enamel and that mechanical loading in addition to erosive challenges are required.

Minimally Invasive Treatment of an Adult with Severe Pseudo Class III Malocclusion

Pseudo class III malocclusion is reverse anterior occlusion or anterior cross-bite with first molars and canines in a class I relationship. It is very important to diagnose the pseudo class III from true skeletal class III. The combination of anterior displacement of the mandible, tooth wear, and loss of occlusal vertical dimension (OVD) in adults may result anterior cross-bite. The key factor in diagnosis of this malocclusion is an interdisciplinary approach with an orthodontist. Cephalometric images are essential for diagnosis of pseudo class III mal-occlusion. Most relevant publications on correcting this condition have recommended either full-coverage restorations or extraction and placement of implants to correct this malocclusion. Advances of material and technology may help dental practitioners to restore tooth wear and OVD with a conservative approach without removing more tooth structures. This clinical report shows the treatment of pseudo class III with minimally invasive treatment using partial coverage restorations fabricated with lithium disilicate.

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.

Oral Rehabilitation With Orthognathic Surgery After Dental Implant Placement for Class III Malocclusion With Skeletal Asymmetry and Posterior Bite Collapse

Increasing numbers of older patients are seeking orthognathic surgery to treat jaw deformity. However, orthodontic and orthognathic surgical treatment is difficult in cases without occlusal vertical stop. A 55-year-old man presented with Class III malocclusion and mandibular protrusion including esthetic problems and posterior bite collapse. He underwent dental implant treatment to reconstruct an occlusal vertical stop before orthognathic surgery. His occlusal function and esthetic problems improved after surgery, and his skeletal and occlusal stability has been maintained for 6 years. Dental implant placement at appropriate positions could help to determine the position of the proximal segment at orthognathic surgery and could shorten the time required to restore esthetic and occlusal function. This case demonstrates how skeletal and dental stability can be maintained long after surgery in a patient with jaw deformity and posterior bite collapse.

Risk Assessment for Tooth Wear

Tooth wear has an increasing prevalence in the UK population. The aetiology is commonly multifactorial, and the aetiopathology is through a combination of erosion, attrition, abrasion and abfraction. Erosion is associated with intrinsic or extrinsic acids, and therefore subjects with reflux disease and eating disorders are at increased risk. Fruit juice, fruits and carbonated drink consumption, frequency of consumption and specific habits are also risk factors. Attrition is more prevalent in bruxists. Other habits need to be considered when defining the risk of tooth wear. Abrasion is usually associated with toothbrushing and toothpastes, especially in an already acidic environment. Patients with extensive lesions that affect dentin may be at higher risk, as well as those presenting with unstained lesions. Monitoring of the progress of tooth wear is recommended to identify those with active tooth wear. Indices for tooth wear are a helpful aid.

A Single Visit Direct Technique to Provisionally Restore Occlusion for a Full-Mouth Rehabilitation: A Clinical Report

Attrition of the dentition can negatively affect esthetics and function. When reconstructing patients with attrition who require restoration at increased occlusal vertical dimension (OVD), it is necessary to first evaluate the OVD using a removable interim prosthesis to ensure that the patient will tolerate the new position. The transition to fixed interim prostheses has to be carefully planned to achieve the desired OVD. One approach is to prepare all teeth in a single day and place full-arch interim prostheses; however, this can be tiring for the patient and prosthodontist. An alternative approach is to prepare one arch and place interim prostheses, while using composite resin in the opposing arch to maintain the newly established OVD. A diagnostic wax-up at the proposed OVD is completed and duplicated in stone. A vacuform matrix is loaded with composite resin and applied to the unprepared etched teeth of the opposing arch to restore form and occlusion until full contour interim prostheses are placed at a later visit.

Implant-Supported Prosthetic Rehabilitation of a Patient with Localized Severe Attrition: A Clinical Report

Patients usually adapt to their existing occlusal vertical dimension (OVD). It is essential to resolve each of the problems associated with decreased vertical dimension as a result of attrition. This report describes the multidisciplinary dental treatment of a 40-year-old male patient who had severe tooth wear, resulting in reduced vertical dimension. After clinical evaluations, extraoral examination showed a reduction of the lower facial height, drooping, and overclosed commissures. Ten dental implants were placed into the maxillary and mandibular alveolar processes. During the osseointegration period, an interim removable partial denture was made at increased OVD to use in the first stage of rehabilitation. It was used for 3 months as a guide for preparing the definitive restorations. The patient's adaptation to the increased OVD was evaluated. During this period, he was asymptomatic. Following the evaluation period, the provisional fixed restoration was used for 3 months. Then, full-mouth definitive prostheses supported by a combination of implants and teeth were fabricated to upper and lower jaws. Osseointegration of the implants, peri-implant mucosa health, prosthesis function, and esthetics were assessed after 1 week and 1, 3, and 6 months. After 3 years of follow-up, no functional or esthetic difficulties with the implants and restorations were noted.

Full-mouth rehabilitation of severely worn dentition due to soda swishing: a clinical report

Diagnosis and treatment planning of severely worn dentition are complex and complicated. Erosion is one of the common causes of lost tooth surface. Defining the etiology of the erosion is essential before proceeding with treatment to be able to provide the most predictable treatment outcome. Multiple specialists including psychologists, family medicine practioners, and social workers should be involved in the diagnosis and the prevention of a continuing erosion process. The treatment plan should be based on the severity of the tooth surface lost. It can range from simple direct restorations to a full-mouth rehabilitation. This clinical report is a detailed description of a complex prosthodontic diagnostic index class IV patient based on current evidence-based dentistry.

Use of zirconia to restore severely worn dentition: a case report

The management of tooth wear has been a subject of increasing interest from both preventive and restorative points of view. Severe tooth wear is frequently multifactorial and variable. Successful management is a subject of interest in dentistry. A critical aspect is to determine the occlusal vertical dimension (OVD) and a systematic approach that can lead to a predictable and favorable treatment prognosis. Management of patients with worn dentition is complex and difficult. Accurate clinical and radiographic examinations, a diagnostic wax-up, and determining OVD are crucial. This paper describes the full-mouth rehabilitation of a 47-year-old bruxer with a severely worn dentition.

Prosthodontic rehabilitation of the patient with severely worn dentition: a case report

The management of tooth wear has been a subject of increasing interest from both preventive and restorative points of view. This paper describes the full mouth rehabilitation of a 63-year-old bruxer man with a severely worn dentition and other dental problems including unsuitable restorations and several missing teeth. The treatment entailed using cast posts and cores, metal-ceramic restorations, and a removable partial denture. As with the treatment procedure of such cases, equal-intensity centric occlusal contacts on all teeth and an anterior guidance in harmony with functional jaw movements were especially taken into account.

Prosthodontic management of worn dentition in pediatric patient with complete overlay dentures: a case report

Overlay complete dentures are simple, reversible and economical treatment modality for patients with congenital or acquired disorders that severely affect the tooth development. It satisfies both the esthetic and functional demands where the extraction of teeth is not generally indicated. In pediatric patients, the overlay dentures establish a relatively stable occlusion that improves patient's tolerance to the future treatment procedures for worn dentition. This clinical report highlights the imperative need of appropriate treatment strategy and application of maxillary and mandibular overlay dentures in a pediatric patient who suffered from congenitally mutilated and worn dentition.

Comprehensive Oral Rehabilitation of a Patient With Dentinogenesis Imperfecta

INTRODUCTION

The treatment of dentinogenesis imperfecta is complex and requires a team approach. The aim of this case report is to describe the steps taken in the long-term rehabilitation of a middle-aged female with dentinogenesis imperfecta with severe attrition. This treatment included an initial temporary treatment to restore esthetic appearance and function followed by a complete prosthetic rehabilitation with implants in the second stage. In advanced stages of dentinogenesis imperfecta, patients can benefit from full-mouth rehabilitation where the deteriorated - yet still present - teeth can be used as abutments for a fixed, temporary restoration throughout the stages of treatment. Detailed pretreatment planning of how much bone and soft tissue are to be removed and an accurate determination of where the implants should be placed must be considered very thoroughly.

CASE PRESENTATION

All teeth were ultimately extracted and replaced with fixed implant-supported prostheses in a staged approach using remaining teeth for interim support and/or retention of provisional prostheses.

CONCLUSIONS

Early and accurate diagnosis of dentinogenesis imperfecta is essential to enable preventive interventions. In many patients, this has not occurred and severe loss of tooth structure, esthetics, and function results. If restorability and prognosis of these teeth are questionable or poor, their replacement with implant-supported fixed or removable prostheses should be the treatment of choice in modern dentistry. Given the appropriate indication and availability of financial means, a fixed solution appears preferable for reasons documented in this case presentation.

A treatment protocol for restoring occlusal vertical dimension using an overlay removable partial denture as an alternative to extensive fixed restorations: a clinical report

Treatment options for patients with severe attrition resulting in reduced occlusal vertical dimension are often limited to fixed prosthesis to reestablish proper occlusal vertical dimension and functional occlusion. In some cases such as when there are limited finances, minimal esthetic concerns, and medical considerations fixed prosthesis may not be the ideal treatment option. Overlay removable partial dentures (ORPDs) can be used as a provisional or interim prosthesis as well as permanent prosthesis in these cases. While ORPDs can provide a reversible and relatively inexpensive treatment for patients with a significantly compromised dental status, there is not much scientific evidence in the literature on ORPDs. Most studies published on ORPDs to date are primarily reviews and clinical reports. In this article, literatures on ORPDs are summarized and a patient treated with interim and permanent ORPDs is presented. This article reviews previously published literatures on the use of ORPDs. Indications, advantages and disadvantages are discussed. Treatment protocol with an example of the prosthodontic treatment of a patient with severely worn dentition with an interim ORPD and later a permanent ORPD are discussed in details.

Prosthodontic rehabilitation of a bruxer patient with severely worn dentition: a clinical case report

The management of tooth wear has been a subject of increasing interest from both preventive and restorative points of view. This article describes the full mouth rehabilitation of a 54-year-old bruxer woman with a severely worn dentition and other dental problems including unsuitable restorations and several missing teeth. The treatment entailed using cast posts and cores, metal-ceramic restorations, and a removable partial denture. As with the treatment procedure of such cases, equal-intensity centric occlusal contacts on all teeth and an anterior guidance in harmony with functional jaw movements were especially taken into account.

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Severe tooth wear is discussed from the perspective of appreciating the aetiologic background of the problem. A multifactorial basis is acknowledged for the extensively worn dentition and efforts to eliminate or minimize these underlying factors are important. The management of a case of severe incisal and occlusal wear can adopt different approaches. The author proposes the rationale and advantages for involving orthodontic preparation as part of the occlusal rehabilitation.

A comparison of debonding strengths of four metal-ceramic systems with and without opaque porcelain

STATEMENT OF PROBLEM

When performing an adjustment on metal-ceramic restorations, opaque porcelain may become exposed, particularly on the lingual surface of maxillary anterior teeth. It is generally believed that exposed opaque porcelain can be more abrasive and destructive to an opposing dentition than body porcelain, and that these teeth may require restoration as a consequence.

PURPOSE

This study compared the debonding strengths of 2 types of porcelain, with and without opaque porcelain, to 2 types of dental casting alloys.

MATERIAL AND METHODS

Two porcelain systems, Ceramco3 and Vita 900, and 2 metal alloys, a high noble (Encore) and a base metal (Duceranium U), were used to fabricate and test 56 flexure bars in accordance with ISO 9693:1999(E): Metal-Ceramic Dental Restorative Systems. Half of the bars received opaque porcelain prior to body porcelain additions, and the other half did not. The metal-ceramic debonding strength was determined by using a 3-point flexure apparatus and a mechanical testing device (Instron). A center load was applied at a crosshead speed of 1.5 mm/min(-1) until debonding occurred. In addition to the load-versus-displacement curve, a precision measurement microphone was used to assist in ascertaining the point in time when debonding occurred. Since the sound analysis and the mechanical test were started simultaneously, the debonding load could be more accurately determined. Data were statistically analyzed using 3-way analysis of variance, and all pairwise multiple comparisons were made with the Tukey HSD test (alpha=.05).

RESULTS

The difference in mean debonding strength values for opaqued and non-opaqued flexure bars were statistically significant (P=.028). The mean debonding strength values (MPa) for each metal-ceramic system were as follows: Encore-Opaque-Ceramco3 (EOC), 31.43 +/- 6.92(a); Encore-Opaque-Vita 900 (EOV), 30.37 +/- 3.25(a); Duceranium U-No Opaque-Ceramco3 (DNC), 29.20 +/- 6.97(a); Duceranium U-Opaque-Ceramco3 (DOC), 26.61 +/- 4.98(a); Duceranium U-Opaque-Vita 900 (DOV), 26.15 +/- 4.29(a); Encore-No Opaque-Vita 900 (ENV), 25.45 +/- 4.04(a); Encore-No Opaque-Ceramco3 (ENC), 23.96 +/- 4.14(a); Duceranium U-No Opaque-Vita 900 (DNV), 22.88 +/- 6.15(a). Identical superscript letters denote no significant difference among groups. The precision measurement microphone resulted in selection of a debonding strength/crack initiation load that was lower than the peak load recorded during strength testing.

CONCLUSION

Initial debonding during crack initiation strength testing may not always correspond to the peak load recorded, but rather to the point on the load-versus-displacement curve beyond which the relationship is no longer a straight line. Presence of opaque porcelain generally increased the debonding strength for metal-ceramic systems; however, opaque porcelain may not be necessary for a clinically acceptable metal-ceramic bond for some metal-ceramic systems.

Severe wear and tooth loss in wild ring-tailed lemurs (Lemur catta): A function of feeding ecology, dental structure, and individual life history

The ring-tailed lemurs at Beza Mahafaly Special Reserve, Madagascar, exhibit a high frequency of severe wear and antemortem tooth loss. As part of a long-term study, we collected dental data on 83 living adult ring-tailed lemurs during 2003 and 2004. Among these individuals, 192 teeth were scored as absent. The most frequently missing tooth position is M1 (24%). As M1 is the first tooth to erupt, its high frequency of absence (primarily a result of wear) is not remarkable. However, the remaining pattern of tooth loss does not correlate with the sequence of eruption. We suggest that this pattern is a function of 1) feeding ecology, as hard, tough tamarind fruit is a key fallback food of ring-tailed lemurs living in gallery forests; 2) food processing, as tamarind fruit is primarily processed in the P3-M1 region of the mouth; and 3) tooth structure, as ring-tailed lemurs possess thin dental enamel. The incongruity between thin enamel and use of a hard, tough fallback food suggests that ring-tailed lemurs living in riverine gallery forests may rely on resources not used in the past. When comparing dental health in the same individuals (n=50) between 2003 and 2004, we found that individual tooth loss can show a rapid increase over the span of one year, increasing by as much as 20%. Despite this rapid loss, individuals are able to survive, sometimes benefiting from unintentional assistance from conspecifics, from which partially processed tamarind fruit is obtained. Although less frequent in this population, these longitudinal data also illustrate that ring-tailed lemurs lose teeth due to damage and disease, similar to other nonhuman primates. The relationship between tooth loss, feeding ecology, dental structure, and individual life history in this population has implications for interpreting behavior based on tooth loss in the hominid fossil record.

Wear of teeth due to occupational exposure to airborne olivine dust

OBJECTIVES

To clarify whether high tooth wear of employees in a mining industry that extracts the mineral olivine could be associated with airborne dust exposure in their working environment.

METHOD

The cumulative exposure to airborne mineral dust for the workers in the company was calculated on the basis of their period of employment multiplied by the airborne olivine-dust concentrations, which have been monitored continuously during the past 20 years for all divisions of the company. After invitation, 85% of the employees (n = 191) were examined clinically and their dentitions were photographed and duplicated in plaster casts. Four clinicians, working independently, examined the sets of casts/photographs for tooth wear and ranked these from most to least. Two groups of employees were compared with regard to tooth wear, i.e. the 30% with the highest (case) and the lowest (control) estimated dust exposure levels. Tooth wear in the case and control groups was compared using a non-parametric test based on rankings (Mann-Whitney test).

RESULTS

Tooth wear differed significantly between the workers in the low and the high mineral dust exposure groups (p < 0.001). The differences were also apparent within three age subsets, although statistical significance was reached only in the 34-44 years subset (p = 0.002). Considerable individual variation was noted within the three exposure groups.

CONCLUSION

Workers with high exposure to airborne olivine dust may contract considerable tooth wear.

Attrition, abrasion, corrosion and abfraction revisited

OVERVIEW

The authors propose updated and revised nomenclature, definitions and classification for tooth surface lesions. Their objective is standardization, clarity and clinical utility for the dental practitioner. The article presents a schema of the pathodynamic mechanisms in the formation of tooth surface lesions--three basic physical and chemical mechanisms, their interactions and their dental manifestations.

CONCLUSIONS AND CLINICAL IMPLICATIONS

The use of precise definitions will assist the practitioner in determining the etiology of various tooth surface lesions. Understanding the pathodynamic mechanisms and their many possible interactions, as set forth in the schema, will enable the practitioner to make an accurate differential diagnosis and to provide effective prevention and treatment. It also will assist dentists in communicating more effectively with their colleagues as well as with their patients. In addition, the schema helps identify areas in which future research is indicated.

Maxillary and mandibular overlay removable partial dentures for the restoration of worn teeth

This clinical report describes the fabrication of maxillary and mandibular cast overlay removable partial dentures for the restoration of severely worn teeth with accompanying loss of vertical dimension of occlusion. The frameworks supported porcelain veneers for esthetics and metal occlusal surfaces for strength and durability.