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PubMedDate not supplied

6-year clinical evaluation of fired ceramic inlays.

The purpose of the present study was to evaluate the quality of fired ceramic inlay restorations consisting of a feldspathic porcelain system (G-Cera Cosmotech II) after 6 years in vivo. A total of 49 fired ceramic inlays (for 27 premolars and 22 molars: class 1 in 11 teeth, class 2 in 36 teeth, and onlays in two teeth) were placed in 29 patients, and all restorations were evaluated at the time of placement, at 6 months, and 1, 2, 4, and 6 years after placement using modified USPHS criteria. Replicas made of the restorations were observed using a scanning electron microscope (SEM) to assess the state of the marginal area and wear of the restoration. Favorable color match was noted, and no bulk fracture, tooth fracture, or missing restorations were detected. Longevity was observed in 92% of the fired ceramic inlay restorations at 6 years (Kaplan-Meier method); however, marginal fracture was detected in six restorations (13%) and marginal discoloration in 11 (23%). SEM evaluation disclosed marginal microfracture in 49% of the restorations, wear in 19%, and wear of resin cement along margins in 36% at 6 years. No significant difference was observed in the incidence of each of these three characteristics between molars and premolars. This longitudinal 6-year clinical observation suggested that fired ceramic inlay restorations made by the G-Cera Cosmotech II system are aesthetic, durable, and clinically acceptable. Further follow-up is needed for the restorations showing marginal degradation and fracture from a microscopic and macroscopic perspective.

Dental Marginal Adaptation↗
PubMed1990

Wear of materials used in dentistry: a review of the literature.

This is a review of the literature concerning wear related to the following materials used in dentistry: dental amalgam, composite resins, and glass-ionomer cements, as well as natural tooth substance. Discussions are included on both in vivo and in vitro studies in which various methods were used to help determine wear resistance.

Composite Resins↗
PubMed2005

In vitro wear resistance of three types of composite resin denture teeth.

STATEMENT OF PROBLEM: The wear resistance of artificial teeth is important to the life of the removable prosthesis for the edentulous patient. The ability of artificial teeth to maintain a stable occlusal relationship over time may be influenced by this property. PURPOSE: The purpose of this in vitro study was to evaluate the wear resistance of artificial teeth based on composite resin filler content when opposed by a denture tooth antagonist. MATERIAL AND METHODS: The right first molars (both maxillary and mandibular) of 3 composite resin denture teeth (Endura, 47% organic filler; Duradent, 42% organic and inorganic filler; and Duracross, 68% organic filler) were secured in an in vitro 2-body wear-testing apparatus that simulated masticatory function (60 strokes/min, grinding distance of 2 mm, under 37 degrees C flowing water). Wear resistance was assessed as volume loss (mm3) and height loss (mm) at 5 kgf (grinding force) after 50,000 strokes (6 pairs for each type). The Vickers microhardness (VHN) of the occlusal surfaces was measured with a load of 50 g and a loading time of 30 seconds. After testing, the worn surfaces were observed with a scanning electron microscope (SEM). Mean values were analyzed using a 1-way analysis of variance followed by the Fisher test (alpha=.05). RESULTS: The volume loss of Duradent teeth (0.87 +/- 0.03 mm3) was significantly higher than of the 2 other types of teeth tested (P<.001). The Duracross teeth (0.22 +/- 0.08 mm3 and 0.11 +/- 0.04 mm) exhibited the best wear resistance of the denture teeth tested. The wear resistance of the materials tested was consistent with their hardness (Endura 27.54 +/- 0.67 VHN, Duradent 24.00 +/- 0.60 VHN, Duracross 39.64 +/- 3.11 VHN). SEM observation showed that many filler particles were missing from the matrix of Duradent. CONCLUSION: The wear resistance among the 3 types of teeth was significantly different; Duracross and Endura were more wear resistant than Duradent. Although the densities as reported by the manufacturer were similar, hardness and microstructure were the primary factors affecting the wear resistance of artificial teeth. Hardness appears to correlate with wear resistance since the wear resistance of Duradent with a lower VHN of 24 was greater than the other 2 types of teeth with greater hardness.

Analysis of Variance↗
PubMedDate not supplied

Restoring the worn dentition.

Strong dental materials and dental porcelains are providing dentists with restorative opportunities that are more conservative because they require less destruction of healthy tooth structure and yield a more esthetic result. In cases of severe wear due to attrition, abrasion, and erosion, this process can be stopped, restoring the esthetics and function by using proper techniques and materials. The case report described in this article demonstrates the conservative restoration of severe wear due to attrition and erosion. Teeth were lengthened, wear was restored, and further wear was ceased by using a combination of bonded porcelain, a heat, light, and self-cure resin system, and a new glass-ionomer restorative material. The result was a strong, durable restoration (that required no anesthesia) with high esthetics.

Adult↗
PubMed1999

Three-body wear of a hand-consolidated silver alternative to amalgam.

Recent studies have investigated a mercury-free silver alternative to amalgam, but the silver powders required a relatively high compaction pressure to consolidate. The aim of the present study was to consolidate a precipitated silver powder into a cohesive solid using an air-driven pneumatic condenser fitted with an amalgam plugger at a clinically realistic load, and to study the mechanisms and rates of three-body wear of the consolidated silver in comparison with that of an amalgam. The silver powder was annealed, rinsed with a dilute acid, and consolidated either in a prepared tooth cavity or in a specimen mold at a load of 15 N. A four-station wear machine was used where each specimen was immersed in a slurry containing polymethyl methacrylate beads, then a steel pin was loaded and rotated against the specimen at a maximum load of 76 N. The flexural strength in MPa (mean +/- SD; n = 10) was 86 +/- 20 for amalgam, 181 +/- 45 for silver with a polished surface, and 202 +/- 21 for silver with a burnished surface. After 4 x 10(5) wear cycles, the wear scar depth in microm was 134 +/- 54 for amalgam, 143 +/- 8 for polished silver, and 131 +/- 9 for burnished silver, which were not significantly different (Tukey's multiple comparison test; family confidence coefficient = 0.95). SEM examination revealed cracks and fracture pits in the worn surface of amalgam, in contrast to a smooth surface in silver. Wear and material removal in amalgam occurred by microfracture and dislodgement of cracked segments, while wear in the silver occurred by ductile deformation and flow of materials. To conclude, the consolidated silver possesses a three-body wear resistance similar to that of amalgam, and a higher resistance to wear-induced damage and cracking than amalgam. The mechanism of wear in amalgam is microfracture and material dislodgement, while that in consolidated silver is ductile deformation and flow of material.

Compressive Strength↗
PubMed1994

Correlates of tooth loss in a Canadian adult population.

Oral health data collected from a mail survey of an Ontario population of adults aged 18 years and over were used to conduct a preliminary investigation of the incidence and correlates of tooth loss and to explore its functional, psychological and social consequences. Of the sample of 500 dentate subjects, 10 per cent reported losing one or more teeth in the previous year. Comparisons between those with and without tooth loss showed significant differences according to age, household income and place of birth. Those subjects wearing partial dentures, possessing fewer teeth at the start of the study period, or who only attended the dentist when having pain or other trouble, were also more likely to have experienced tooth loss in the preceding year. Logistic regression analysis identified only age as a significant independent risk factor. Subjects who lost teeth were significantly more compromised in their oral functions and psychosocial behaviors, as measured by a battery of subjective oral health indicators. Whether or not these problems were pre-existing or the consequences of losing teeth during the past year cannot be determined from this study. This investigation suggests that tooth loss is still a concern for many Canadian adults, and demonstrates the importance of teeth in their overall well-being.

Adolescent↗
PubMed1995

A survey of tooth injury experience and attitudes to prevention in a group of Singapore schoolboys.

A survey of 246 boys aged 12-17 years (mean 13.8 years) determined the sports played, dental injury experience, knowledge and usage of and attitudes towards mouthguard wearing. Most played basketball and soccer. Twenty-one suffered 1 injury episode, 7-2 and 10-3 or more tooth injuries. Twenty-six subluxations, 19 fractures and 1 avulsion were reported. The sports with the highest prevalence of dental injury were boxing and wrestling (33%), soccer (20%), and basketball (19%). While 144 (56%) of boys knew about mouthguards, none wore one. Only 64 (25%) would wear a mouthguard if given one. Most dental injuries were minor, but four high-risk sports (> 19% injury prevalence) would justify preventive measures, including education for injury prevention and encouragement of mouthguard use.

Adolescent↗
PubMed2006

Prevalence and side preference for tooth grinding in twins.

BACKGROUND: Estimates of the prevalence of tooth grinding in children range considerably, reflecting different methods of recording. The main aims of this study were to determine the prevalence of tooth grinding in monozygotic (MZ) and dizygotic (DZ) twin pairs by assessing wear faceting on the primary canines, and to compare the faceting on the right and left to determine whether children have a side preference for grinding. METHODS: The sample consisted of 116 MZ twin pairs and 124 dizygous DZ twin pairs, all participants in an ongoing study of dento-facial development at the dental schools in Adelaide and Melbourne. Evidence of wear faceting on primary maxillary and mandibular canine tips was recorded from dental casts, and the side with the larger wear facet recorded. Types of occlusal relationship, handedness, zygosity and gender were also recorded, and associations between variables analysed statistically. RESULTS: Canine tip wear facets were found in 100 per cent of the sample, and grinding was lateralized in 59 per cent of children. MZ twin pairs showed a higher discordance for grinding side preference than DZ twin pairs (33.8 per cent compared with 16.8 per cent), providing evidence of a mirror-imaging effect for grinding side preference. There was no strong evidence that individuals had the same preference for grinding side and handedness, although right-handers (RH) showed a preference for a grinding side more often than non-right-handers (NRH) (63.6 per cent compared with 51.2 per cent), consistent with previous findings that RHs display more cerebral lateralization than NRHs. CONCLUSIONS: Tooth grinding appears to be a universal phenomenon in children and is commonly expressed more on one side than the other. The significantly higher discordance for grinding side preference in MZ twin pairs compared with DZ twin pairs may reflect a mirror-imaging effect in the former. However, at present we have no evidence to suggest that handedness and preferred tooth grinding side are associated.

Adolescent↗
PubMed1997

Issues related to single-tooth implants.

Many practitioners place single-tooth implants when the teeth adjacent to the edentulous space are intact, free of caries and have had no restorations, and the patient is reluctant to wear a removable appliance for physical or psychological reasons, or both. The main exclusionary factors for a single-tooth dental implant are insufficient bone quantity, poor bone quality and insufficient vertical interarch space to accommodate the prosthodontic components of the implant.

Biocompatible Materials↗
PubMed1976

Quantitative changes in dental plaque formation related to removable partial dentures.

Plaque formation on forty-four teeth acting as abutments for removable partial dentures was studied while the patients were wearing their dentures and while they were not. The amount of plaque was assessed according to Quigley & Hein (1962), modified by Kardel & Bay (1967). In addition, that formed occlusally was evaluated by an occlusal plaque scoring index designed for the present study. It was found that the wearing of partial dentures increased the formation of plaque on all tooth surfaces under investigation.

Adult↗
PubMed1994

Indentation cracking of composite matrix materials.

Composite restorative materials wear by a fatigue mechanism in the occlusal contact area. Here, tooth cusps and food debris cyclically indent the restoration. Modeling this phenomenon requires an understanding of material response to indentation. The question in this study was whether material response depends on indenter size and geometry, and also, whether polymers used in restorative materials should be considered elastic and brittle, or plastic and ductile for modeling purposes. Three resins used as matrices in proprietary restorative composites were the experimental materials. To ascertain the influence of glass transition temperature, liquid sorption, and small amounts of filler on indentation response, we prepared materials with various degrees of cure; some samples were soaked in a 50/50 water/ethanol solution, and 3 vol% silica was added in some cases. Indentation experiments revealed that no cracking occurred in any material after indentation by Vickers pyramid or spherical indenters with diameters equal to or smaller than 0.254 mm. Larger spherical indenters induced subsurface median and surface radial and/or ring cracks. Critical loads causing subsurface cracks were measured. Indentation with suitably large spherical indenters provoked an elastoplastic response in polymers, and degree of cure and Tg had less influence on critical load than soaking in solution. Crack morphology was correlated with yield strain. Commonly held assumptions regarding the brittle elastic behavior of composite matrix materials may be incorrect.

Bisphenol A-Glycidyl Methacrylate↗
PubMed1997

Use of the Empress all-ceramic restoration system.

New dental materials and techniques have been introduced in the past few years to fabricate aesthetic ceramic restorations with improved strength, biocompatibility, resistance to wear, and better fit. Aesthetic concerns and increasing demand for tooth-colored posterior restorations have led to a number of all-ceramic restorations such as IPS Empress (Ivoclar-Williams, Amherst, NY). The Empress system offers superior aesthetics and physical properties. New generation ceramics along with the current adhesive techniques have resulted in the ability to provide higher strength, therefore indicating crowns for posterior restorations as well. These materials are being used more frequently and in more extensive oral prosthetic rehabilitations such as the case that will be presented. We discuss the different properties and advantages of IPS Empress.

Adult↗
PubMedDate not supplied

Adult growth, aging, and the single-tooth implant.

Single-tooth implants are an increasingly popular method for replacing single teeth. While the effects of growth on implants in children have been well documented, the changes that occur in adults have not been studied with respect to single-tooth implants. It has been assumed that adults are stable and do not change; however, research in the last few years has indicated that adults do change with aging, and adult growth does occur. The changes in adults occur over decades rather than rapidly, as seen in children. Aging changes are readily apparent in the soft tissues of the face and create dramatic changes. Changes in the jaws and teeth occur as a result of continued, slow growth, in contrast to the aging effects seen in soft tissues. Growth changes occur in the arches and result in adaptive changes in the teeth over time, both vertically and horizontally, and in alignment. These dental changes may result in a lack of occlusion vertically or malposition of adjacent natural teeth relative to the implant crown. Clinicians may be well advised to observe and report these changes and warn patients that changes can occur over the service life of the implant-supported crown. These changes may require maintenance adjustments or possible remaking of the implant crown as a result of adult growth, wear, or the esthetic changes of aging.

Adult↗
PubMed1984

The pathogenesis of excessive wear in the deciduous teeth of sheep.

The teeth and various supporting and ancillary tissues were examined post mortem from two flocks of sheep, one of which had previously shown high deciduous incisor wear. Sheep were killed in groups selected on clinical signs at equivalent ages from birth to 116 weeks of age. At the end of this time the lengths of clinical crowns of the remaining deciduous incisor teeth in the high wear flock were not measurable, whereas the other flock had up to 5.5 mm in visible crown. Using the cingulum as a marker, measurements were made from extracted teeth of the attrition of the crown and size of the root. The tooth root did not grow substantially longer after the 13th week of the sheep;s life. Wear facets were just visible in some sheep at six weeks. More rapid wear occurred three times in the high wear flock. The first of these was relatively small and occurred between the 13th and 27th week of age in I1 and I2. The second was larger and occurred between the 38th and 57th week of age in the winter/spring period. A third period of wear, which was not measured from the cingulum, because this structure had by then been worn away, was seen in the remaining deciduous teeth between the ages of 91 and 110 weeks of age, i.e., during the second winter and spring. In the low wear flock the first of these periods of wear did not occur, the second was of shorter duration and smaller size, and the third equivocal. Eruption of the teeth after the 6th week was principally passive. There was no difference in the degree of wear of the molar teeth from the two flocks. Histological examination showed that the wear was compensated for by the deposition of reparative dentine in the pulp cavity. This usually gave the appearance of an ordered process. However, when wear was excessively rapid, a different, less orderly form of reparative dentine was laid down. In a few cases the reparative process was not fast enough, and a connection developed between the mouth and the pulp causing pulpitis. There was no histological evidence that the supportive tissues of the teeth, or the upper dental pad, contributed to the excessive wear.

Journal Article↗
PubMed2002

Characteristics of noncarious cervical lesions: a clinical investigation.

BACKGROUND: The purpose of the authors' in vivo investigation was to analyze the characteristics of noncarious cervical lesions, or NCCLs, in adult patients who had a high incidence of them. METHODS: The patient pool consisted of a total of 57 patients and 171 teeth (three teeth per patient), with one NCCL per tooth. The characteristics the authors evaluated were shape, dimensions, sensitivity, sclerosis and occlusion. RESULTS: In terms of lesion characteristics, 91 percent of the lesions had axial depths of 1 to 2 millimeters, 49 percent had occlusogingival widths of 1 to 2 mm, 74 percent had an angular shape of 45 to 135 degrees, 76 percent had mild or moderate sclerosis, and 73 percent had no or mild sensitivity. In terms of occlusion, 75 percent of teeth had an Angle Class I occlusion on the involved side, 60 percent had group function or mixed excursive guidance, 82 percent had wear facets, and 99 percent had Type 0 or I mobility. In terms of tooth location, 70 percent of NCCLs were on posterior teeth, 65 percent were on maxillary teeth, and 46 percent were on premolars. CONCLUSIONS: The evaluated NCCLs were found mainly to have small dimensions of depth and width (< 2 mm) and to be roughly right-angled in shape, and many had sclerosis and low sensitivity. A majority of the dentitions studied had Class I occlusion, with group function, prevalent wear facets, and little or no mobility. Cervical lesions were more common with posterior maxillary teeth and premolars, especially first premolars, which had the highest prevalence of lesions. Older patients were more likely to exhibit noncarious cervical lesions, but no great difference in incidence was found between men and women. Clinical Implications. A knowledge of the NCCL characteristics and etiologic covariables aids in proper case selection for treatment, aids in selection of appropriate treatment protocols and improves assessment of prognosis.

Adult↗
PubMed2006

Eight year results with direct ceramic restorations (Cerana).

BACKGROUND: Single-visit system ceramic restorations are now in use to provide an alternative to resin-based materials. Inserts have been shown to improve characteristics of composite restorations. OBJECTIVE: To investigate the longevity of Cerana (Nordiska Dental, Sweden) in a prospective clinical trial. METHODS: Cerana restorations use matched drills with pre-etched and silanated leucite inserts cemented using a conventional restorative composite resin material. The results of 33 Cerana restorations up to eight years (25 Class I, eight class II) are presented. Restorations were reviewed and assessed by two examiners using modified USPHS criteria for anatomical form (AF) A-C, marginal adaptation (MA) A-D, surface roughness (SR) A-D, marginal discoloration (MD) A-C, colour match (CM) A-C and discomfort (DT) A-D as well as retention. RESULTS: The percentage of A scores for AF, MA, SR, MD, CM and DT at baseline (n = 33) were: 100, 100, 79, 100, 21, 100; after two years (n = 27) 100, 85, 33, 100, 19, 100 and after four years (n = 24) 96, 75, 17, 96, 25, 100. At six years (n = 20) 95, 70, 10, 95, 15, 100 and finally at the eight year recall (n = 18) 94, 61, 0, 94, 6, 100. AF was maintained in all except for one fractured marginal ridge. MA of the insert was good but composite was lost where exposed. SR increased to a B score for all inserts. MD at B grade was observed in 6% between composite and tooth but none between insert and composite. CM was stable in all cases. DT nil in all. There were no scores less than B. All reviewed restorations were retained, clinically acceptable and in function except for two lost for reasons not directly related to the Cerana insert. One class II restoration had a fractured marginal ridge but otherwise remains satisfactory. CONCLUSIONS: The results suggest that these restorations can be expected to perform well. Cerana is acceptable in terms of aesthetics, patient acceptance, occlusal wear and ease of use and is a good alternative for a single-visit, tooth coloured restoration in suitable cavity shapes.

Aluminum Silicates↗