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PubMed2002

The role of occlusal stress and gingival infection in the formation of exostoses on mandible and maxilla from Neolithic China.

Exostoses on the mandible and maxilla is a frequently observed bone growth of controversial aetiology. The aim of this study is to analyse environmental factors that may stimulate the formation of exostoses on different regions of the maxilla and mandible. Sixty-six well-preserved crania from Neolithic China were studied for the presence of buccal exostoses on the maxilla (BE) and lingual exostoses on the mandible (LME). Other oral health indicators, such as occlusal wear on molars, pathology of temporomandibular joint (TMJ), carious lesions, calculus accretion, periodontal disease, and antemortem tooth loss were recorded. Buccal maxillary exostosis was unusually common on the Neolithic skulls from China, which thus resemble the Sinantropus crania described by Weidenreich (1943). We report a significant Spearman correlation between BE and LME (rho = 0.54, P < 0.00001), suggesting a partially shared aetiology of these two types of exostoses. The highest correlations between either form of exostoses and any oral indicator of stress were found for pathology at TMJ (rho = 0.46, P < 0.0001 for both types of exostoses). Smaller but significant correlations were observed between LME and the age adjusted wear rate on lower molars, as well as between BE and indicators of oral/dental pathology, e.g. caries, calculus, periodontoses, and antemortem tooth loss. Both types of exostoses tended to increase in frequency with age, although a significant trend was observed only for BE. We conclude that formation of exostoses is a complex process that can be invoked by any agent causing damage and inflammation of gingival tissue. However, severe occlusal stress, which is often manifested in TMJ disorder, is the main environmental factor leading to exostosis development in genetically pre-disposed individuals.

Adult↗

PubMed1988

Activity-induced patterns of dental abrasion in prehistoric Pakistan: evidence from Mehrgarh and Harappa.

A detailed investigation of worn teeth should reveal a record of past activity patterns including information regarding diet, food preparation methods, and craft or occupational activities. Anthropological studies of the extensive dental samples from Neolithic (MR 3) and Chalcolithic (MR 2) levels at Mehrgarh, Baluchistan, and Bronze Age Harappa, Punjab, yielded several interesting examples of unusual dental abrasion. This paper provides macro- and microscopic (scanning electron microscope) descriptions of three types of activity-induced dental abrasion: 1) interproximal tooth grooving and interproximal abrasion patches, 2) facial abrasion of maxillary anterior teeth, and 3) lingual abrasion of maxillary incisors in association with rounded wear of lower incisors. The gross size and shape of abrasion features, the orientation of microscopic wear striae, and ethnographic parallels are employed in inferring causal factors involved in their formation. Behavioral activities and dietary explanations possibly associated with each type of dental wear are considered and their implications for reconstructing prehistoric activity patterns discussed. The need for extensive ethno-anthropology research into variations of tooth use among living people with different diets, subsistence bases, and craft specializations is essential to further progress in this field.

Female↗

PubMed1993

Study on high-strength plastic teeth. Tooth discoloration.

Conventional plastic teeth (CV teeth) are inferior to porcelain teeth in maintaining an adequate esthetic appearance with wear and discoloration, and thus have a shorter period of durability. Recently, high-strength plastic teeth (HS teeth) have been developed and applied to overcome the wear problems of CV teeth. Since HS teeth made of hard resin are still susceptible to staining with pigments, it has been observed that the esthetics of removable partial dentures made from such plastic teeth are gradually impaired in many patients. To investigate the susceptibility of HS teeth to pigments, we conducted an in vitro study by immersing three types of artificial teeth in three coloring liquids. It was found that the HS teeth tended to be less susceptible to the test pigments than the CV teeth to various degrees. In contrast, they showed markedly stronger susceptibility to the pigments than porcelain teeth. For all three artificial tooth types, daily tooth cleaning with an ultrasonic vibrator had a tendency to reduce the coloration in comparison with their counterparts without ultrasonic cleaning.

Acrylic Resins↗

PubMed2002

Powered vs manual tooth brushing in fixed appliance patients: a short term randomized clinical trial.

Sixty-three orthodontic patients wearing upper and lower fixed appliances were randomly assigned to use either a powered toothbrush fitted with a modified orthodontic brush head (Braun Oral-B Plaque Remover 3D) or a manual toothbrush (Reach Compact Medium). A trained hygienist instructed each patient on the proper use of the allocated brush. Measurements of plaque and gingival health were made at baseline, at four weeks, and at eight weeks. Data for each group were analyzed using paired t-tests. Patients using the powered toothbrush showed a significant reduction in percentage interdental bleeding scores from baseline to four weeks (-12.7, P = .003) and this was still apparent at eight weeks (-8.6, P = .028), although there were no statistically significant changes in either plaque or gingivitis scores for this group. Those patients using a manual toothbrush showed a significant reduction in mean plaque score from baseline (four weeks = -0.18, P = < .001; eight weeks = -0.12, P = .016), but gingivitis scores were only reduced significantly at four weeks. In this group, interdental bleeding scores reduced significantly at four weeks (P = .028), but were not significantly different from baseline at eight weeks (P = .0319). When the two patient groups were compared using two sample t-tests, there were no significant differences in any of the parameters measured at any time point in the study. Over an eight-week period, there were no measurable differences between the powered toothbrush with modified orthodontic brush head and a manual toothbrush with respect to mean change in plaque, gingivitis, or interdental bleeding scores when used by patients wearing fixed appliances.

Adolescent↗

PubMed2006

Effects of resin formulation and nanofiller surface treatment on in vitro wear of experimental hybrid resin composite.

While adding nonbonded nanofillers and lowering the viscosity of the resin matrix have shown success in reducing deleterious polymerization stresses in dental composites, their effects on wear resistance is unknown. This study evaluated abrasion and attrition wear of experimental composites with varied resin viscosities [inherent to varied ratios of TEGDMA:UDMA:bis-GMA (47:33:16 wt%; 30:33:33 wt%; 12:33:51 wt%)] and nanofiller surface treatment (12.6 wt% silanated or unsilanated silica: OX-50; 0.04 microm). Specimens (n = 6) were light cured, aged in water at 37 degrees C for 7 days, and evaluated in the new OHSU oral wear simulator (100,000 cycles). Nonbonded nanofiller increased abrasion and attrition in the low and medium viscosity composites. Increase in resin viscosity increased abrasion and attrition in composites containing silanated nanofiller, with equivocal effects in composites containing unsilanated nanofiller. Nonbonded nanofiller can lower the overall wear resistance of some composite formulations. Increasing resin viscosity generally lowers the wear resistance, but had minimal effect on composites containing nonbonded nanofiller.

Biocompatible Materials↗

PubMed1996

Properties of a custom-made hinge clasp compared with a conventional circumferential clasp.

The use of the hinge clasp in removable partial denture design, together with the design of a custom-made hinge unit, is discussed in this article. Tests of the retention provided by these custom-made hinge clasps were made, together with conventional clasps, and the results were compared. Six custom-made hinge clasps were constructed and attached to blocks of acrylic resin. The forces required to open these clasps and the effect of wear on the clasps were measured. Six conventional cast clasping units were also constructed and tested. The results indicated that the average force required to open the hinge clasps was 8.13 N (SD 1.99). After a period of simulated wear, the mean value of force required was 7.70 N (SD 2.33) and there was no statistically significant deterioration caused by wear. The mean forces required to withdraw these clasps vertically from a tooth were 30.25 N (SD 6.51) for the conventional clasps and 49.67 N (SD 18.69) for the hinge clasps. It was also found that the hinge clasps had to be withdrawn further from their seated position than the conventional clasps before retention was finally lost. However, neither of these differences were statistically significant.

Dental Clasps↗

PubMed1999

Effect of a fluoride varnish on demineralization adjacent to orthodontic brackets.

Home fluoride regimens have long been used to reduce the amount of demineralization adjacent to orthodontic appliances. In the absence of patient compliance, another method of applying the fluoride must be used. The purpose of this study was to evaluate, in vitro, the ability of a fluoride varnish, Duraflor, to directly inhibit demineralization of enamel surrounding orthodontic brackets. Brackets were bonded to 36 extracted human canines and premolars with a traditional composite resin and randomly assigned to three equal groups of twelve. Group 1 served as the control with no topical application after bonding. Group 2 was treated with a single application of a nonfluoridated placebo varnish. Group 3 was treated with a single application of Duraflor. All groups were cycled in an artificial caries challenge for 1 hour two times daily for 37 days and were brushed with a medium bristled toothbrush to simulate mechanical wear of the varnish. Demineralization of enamel was evaluated in longitudinal buccolingual tooth sections using polarized light microscopy. Both average depth and area of demineralization were measured with a sonic digitizer. ANOVA (P </=. 0001) and Duncan's test (P </=.05) indicated significant differences in depth and area of demineralized enamel. Those teeth treated with Duraflor exhibited 50% less demineralization than the control teeth and an even greater difference when compared to the placebo group. Fluoride varnishes should be considered for use as a preventive adjunct to reduce enamel demineralization adjacent to orthodontic brackets, particularly in patients who exhibit poor compliance with oral hygiene and home fluoride use.

Analysis of Variance↗

PubMed1999

Vertical height loss: an investigation of four restorative materials opposing enamel.

PURPOSE: The objective of this in vitro investigation was to compare the vertical wear produced by cone-shaped styli of three ceramic restorative materials and a Type III gold alloy opposing flattened human enamel. Vertical wear was measured as enamel height loss, material stylus height loss, and total vertical height loss (the sum of the enamel height loss and the restorative material height loss). MATERIALS AND METHODS: Ten cone-shaped styli were fabricated from each of four restorative materials, which included two machined ceramics, a pressed ceramic, and a Type III gold alloy. To maintain the standardized shape, styli were not polished or glazed. Specimens were subjected to wear in the presence of water for 100,000 cycles at 1.2 Hz under a load of 75 N using a wear simulation device. Enamel wear was evaluated by profilometry, and stylus wear was evaluated by computer imaging. Vertical wear was reported as enamel height loss, material stylus height loss, and total vertical height loss (the sum of the enamel height loss and material height loss). Data were compared using one-way analysis of variance and Scheffe's analysis (alpha = 0.05). RESULTS: Significant differences existed among materials based on material height loss (p = .0001), enamel height loss (p = .0001), and total vertical height loss (p = .0118). No significant difference among the three ceramics was found in mean total height loss, which ranged from 0.280 to 0.305 mm. However, the Type III gold exhibited less mean total wear (0.231 +/- 0.082) than the pressed and one machineable ceramic. This machined ceramic exhibited the most material height loss (0.249 +/- 0.044 mm). With the other ceramics, mean enamel wear was significantly more (0.211 and 0.216 mm, respectively). CONCLUSIONS: During wear simulation, pressed or machineable ceramics opposing flattened enamel exhibited a similar degree of total vertical height loss. One machined ceramic material wore significantly more than the other materials. The other machineable ceramic and the pressed ceramic wore the opposing enamel significantly more.

Aluminum Silicates↗

PubMed1988

A review of dental microwear and diet in modern mammals.

Recent work has shown that microscopic wear patterns on teeth may yield insights into variations in diet and tooth use in modern and prehistoric mammals. This paper presents a review of dental microwear and diet in modern mammals, plus a discussion of topics for further research. To date, incisor and molar microwear have been examined, although there are far fewer studies of the former. Facilitated by the use of high-resolution casts and scanning electron microscopy, analyses have ranged from: qualitative to quantitative, low magnification to high magnification, and experimental studies to comparative studies of museum collections. Results are encouraging and may lead to further insights into a variety of topics including food processing and dental microstructure.

Animals↗

PubMed2003

Wear of dental resin composites: insights into underlying processes and assessment methods--a review.

Given the increased aesthetic demands of patients, along with improvements in the formulation of resin composites, the ability of these materials to bond to tooth structures, and concerns about dental amalgam fillings, the applicability of resin composites in dentistry has become increasingly widespread. As resistance to wear represents an important factor in determining the clinical success of resin composite restoratives, the aim of this article was to define what constitutes wear; the major underlying phenomena involved in this process-adhesion, abrasion, fatigue, and corrosion-being described. Discussions were also focused on factors that contribute both to the magnitude and minimization of resin composite wear. Finally, insights were included on both in vivo and laboratory studies used to determine wear resistance.

Animals↗

PubMed2000

The friction and wear patterns of orthodontic brackets and archwires in the dry state.

Frictional resistance at the bracket-archwire interface has been demonstrated to impede tooth movement when sliding mechanics are used. Thus, the coefficients of friction of titanium and stainless steel brackets used in conjunction with stainless and ion-implanted beta-titanium archwires were investigated using a single contact interface between the brackets and archwires. The wear patterns between the brackets and the.016- in flat archwire surfaces were also examined using scanning electron microscopy and energy dispersive x-ray analysis. Stainless steel brackets tested with. 016-in flat stainless steel wire surfaces recorded the lowest coefficient of static friction mean (0.289), whereas titanium brackets paired with.016-in flat ion-implanted beta-titanium wire surfaces produced the highest mean (0.767). Stainless steel brackets had significantly (P <.05) lower coefficients of friction than titanium brackets for all wires except.020-in round stainless steel wires. Ion-implanted beta-titanium wires generally had significantly larger coefficients of friction than stainless steel wires. The increased friction of the titanium and ion-implanted beta-titanium alloys is also reflected in the severity of their wear patterns. An inverse relationship between friction and archwire surface dimension was generally found for ion-implanted beta-titanium wires. Round stainless steel wires demonstrated lower coefficients of kinetic friction than the flat stainless steel wire surfaces.

Analysis of Variance↗

PubMed1999

Clinical and scanning electron microscopic evaluation of fiber-reinforced inlay fixed partial dentures: preliminary results after one year.

STATEMENT OF PROBLEM: Restorative dentistry searches for nonmetal reinforcement of esthetic fixed partial dentures (FPDs). PURPOSE: This clinical study evaluated conservative fiber-reinforced composite FPDs bonded to inlay abutments. MATERIAL AND METHODS: Twenty fiber-reinforced composite inlay FPDs were made for 15 patients. Restorations were manufactured with the Targis Vectris glass-fiber-reinforced composite system and a simplified laboratory technique. The 20 bonded inlay FPDs were examined clinically and by SEM after 1 year. RESULTS: All 20 FPDs were intact at the 1-year examination. There were no signs of fracture, surface defects, or excessive wear with SEM. SEM marginal analysis exhibited 91.6% +/- 5% excellent margins at the tooth-luting composite interface and 86. 1% +/- 8% excellent margins at luting composite/restoration interface. CONCLUSION: On the basis of the results of this descriptive study, bonded glass-fiber-reinforced composite inlay FPDs were considered clinically successful at the 1-year examination.

Composite Resins↗

PubMedDate not supplied

Wear resistance of composites: a solved problem?

During the past few years, the use of posterior composites has increased, due to an increased demand from patients to have their metallic restorations replaced with tooth colored restorations. However, until recently, posterior composites were not considered suitable alternatives to metallic restorations mainly because of their tendency to contract during polymerization and wear more than traditional metallic materials. Improvements in bonding agents and composite materials have now made it possible to produce posterior composites that may not produce excessive long-term wear. Despite these improvements, clinicians may find that some composites wear more than expected in certain patients. By developing a good understanding of the different wear mechanisms, the clinician can become familiar with clinical wear variations and select clinical cases where composites may work well without excessive wear.

Bicuspid↗

PubMed1996

Promotion of mouthguards among amateur football players in Victoria.

Wearing mouthguards while playing contact sports reduces the prevalence and severity of orofacial injuries. We report on a 1991-92 promotion of mouthguard use among amateur football players in Melbourne. Four questionnaires were completed by players (1991 season: middle: n = 638, 49 per cent response: late: n = 770, 51 per cent: 1992: early: n = 505, 26 per cent: late: n = 698, 54 per cent), in four age groups (16-19, 20-23, 24-29, 30-44 years), about perceived mouthguard value and usage, injury experience, and awareness of a promotional message. Over the two seasons, mouthguard ownership and consistent wear increased and dental injuries decreased. Ownership of mouthguards increased among: 20-23 year olds and 30-44 year olds (13 and 16 per cent); managers, tradespersons, salespersons, labourers and the unemployed (14-19 per cent); residents of northern and western regions (12 and 13 per cent); those with 6 to 10 years of education (29 per cent); players in old boys' networks (13 per cent); and those with English as a first language (8 per cent). Consistent wear was high at matches (89 per cent) but low at training (13 per cent), owing to perceived lack of physical contact. Of dental injuries reported by 25-31 per cent, fractures predominated over luxations and avulsions. Fractures and avulsions were more common at matches than training; luxations predominated at training. When a mouthguard was not worn, the likelihood of a fractured or avulsed tooth was at least twice that when a mouthguard was worn. Some injuries occurred despite the wearing of mouthguards. The promotional message appeared effective in increasing mouthguard use; newspapers and football journals provided effective message locations for players, and ground signs and the electronic scoreboard for spectators.

Adolescent↗

PubMed2003

Impact of increased occlusal contact, interleukin-1 genotype, and periodontitis severity on gingival crevicular fluid IL-1beta levels.

BACKGROUND: The study of occlusal therapy in humans with periodontitis is problematic due to potential irreversible bone loss in control subjects. The hypothesis of this pilot investigation was that increased interocclusal contact initiated by short-term occlusal splint disuse would increase tooth mobility and the bone-resorptive cytokine interleukin (IL)-1beta in gingival crevicular fluid (GCF), comparable to IL-1-positive genotype and increased periodontitis severity. METHODS: Nineteen non-smoking chronic periodontitis patients using nocturnal occlusal splints and undergoing periodontal maintenance in a private practice were evaluated at five time points: 24 hours after continuous splint use; 1, 2, and 3 days after no occlusal splint use; and 14 days after resumption of customary nighttime splint use. Subjects were evaluated to confirm that the plaque index and gingival index were < or = 1.0, and to categorize past periodontitis (moderate or severe) and IL-1 genotype (1A +4845 plus IL-1B +3954). Test sites on two anterior teeth vulnerable to occlusal trauma were sampled for mobility, GCF IL-1beta, and IL-1 receptor antagonist (ra). RESULTS: Tooth mobility remained low during the 3-day period when patients were not wearing their occlusal appliance. GCF IL-1beta decreased after not wearing the appliances (P = 0.016), especially at 48 hours. At this time, genotype-positive subjects had higher levels of GCF IL-1beta/IL-1ra than genotype-negative subjects (P = 0.045), and patients who had experienced severe periodontitis had higher IL-1beta levels than moderate periodontitis subjects (P = 0.004). CONCLUSIONS: These findings suggest that short-term discontinuation of occlusal splint therapy in non-smoking periodontitis patients undergoing periodontal maintenance does not result in potential signs of early occlusal trauma (increasing mobility or GCF IL-1beta). Longer-term studies may be needed to determine appropriate therapy applications for periodontitis-susceptible patients with definable occlusal discrepancies and/or parafunction.

Adult↗

PubMed1996

Prognosis versus actual outcome. III. The effectiveness of clinical parameters in accurately predicting tooth survival.

Tooth loss for 100 treated periodontal patients (2,509 teeth) under maintenance care was evaluated to determine the effectiveness of commonly taught clinical parameters utilized in the assignment of prognosis in accurately predicting tooth survival. Previous studies in this series evaluated prognosis as a surrogate variable representing the condition of the tooth at a particular point. In this study, survival analysis was used to evaluate the relationship of these common clinical parameters to an actual end point, tooth loss. Robust log rank tests indicated that initial probing depth, initial furcation involvement, initial mobility, initial crown-to-root ratio, and initial root form were all associated with tooth loss. In addition, smoking and increased initial bone loss were both found to be associated with increased risk of tooth loss while fixed abutment status was associated with a decreased risk of tooth loss. A Cox proportional hazards regression model showed that initial probing depth, initial furcation involvement, initial mobility, initial percent bone loss, presence of a parafunctional habit without a biteguard, and smoking were all associated with an increased risk of tooth loss. This model suggests that patients are twice as likely to loose their teeth if there is increasing mobility, if they have a parafunctional habit and do not wear a biteguard, or if they smoke. From these data there does appear to be a relationship between the assigned prognosis and tooth loss. Teeth with worse prognosis have a worse survival rate, but the commonly taught clinical parameters used in the traditional method of assignment of prognosis do not adequately explain that relationship. Furthermore, initial prognosis did not adequately explain the condition of the tooth or accurately predict the tooth's survival. These results seem to indicate that the effect of these clinical parameters on tooth survival is only partially reflected in the assigned prognosis initially, suggesting that perhaps some of the clinical parameters should be weighed more heavily than others when assigning prognosis. Further studies are needed to develop a more accurate method for the assignment of prognosis.

Alveolar Bone Loss↗

PubMed1999

Tooth movement and vascularity of the dental pulp: a pilot study.

The effect of orthodontic tooth movement on the dental pulp was assessed histologically in twelve subjects. The participants in this study required the extraction of at least two maxillary first premolars for orthodontic treatment. They were asked to wear a maxillary removable appliance that acted to move a randomly determined premolar in a buccal direction. The appliance was designed to avoid contacting the contra-lateral tooth that was used as the matched control. The appliance was initially worn for a week to ensure patient comfort and cooperation. The appliance was then activated and the patient dismissed. After two weeks, the appliance was reactivated. Both the control and experimental teeth were extracted three weeks later, on the thirty-fifth day of activated appliance wear. The teeth were fixed, decalcified and sectioned. The sections were stained with haematoxylin and eosin for histological examination. This investigation demonstrated that orthodontic tooth movement did have an effect upon the dental pulp, causing vasodilation in the pulp of an orthodontically stressed tooth.

Activator Appliances↗

PubMed2003

Toothbrushing and gingival recession.

AIM: To review the hypothesis that toothbrushing leads to gingival recession. Gingival recession develops due to anatomical and pathological factors. The prevalence of recession is dependent on the age and characteristic of the population because it usually presents in individuals with periodontal disease or those who practise zealous or improper oral hygiene methods. Gingival trauma and gingival abrasion from toothbrushing is thought to progress directly to gingival recession. Case studies documenting recession from toothbrush trauma are speculative. Short-term studies suggest that gingival trauma and gingival abrasion may result from toothbrushing, but the direct relationship between traumatic home care and gingival recession is inconclusive. Long-term studies remain elusive or do not support the development of recession following toothbrushing. Nevertheless, tooth abrasion may be an integral part in the aetiology of recession. Toothbrush abrasion also may cause wear at the cemento-enamel junction resulting in the destruction of the supporting periodontium leading to recession.

Gingival Recession↗