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PubMed2005

Relative wear of flowable and highly filled composite.

STATEMENT OF PROBLEM: By decreasing the proportion of filler, flowable composites are easy to adapt to small cavity preparations. However, the wear resistance of flowable composites is a clinical concern, as improved wear has been related to increased filler percentage. PURPOSE: The purpose of this study was to compare wear for flowable composites and comparable heavily filled materials. MATERIAL AND METHODS: Wear by attrition and abrasion (microm) of microfilled flowable (Heliomolar Flow) and heavily filled microfill (Heliomolar HB) was measured and compared to a microhybrid flowable (Tetric Flow) and a heavily filled microhybrid (Tetric HB). There were 5 specimens, 2 mm thick and 15 mm in diameter, in each group. The Oregon Health Sciences University oral wear simulator was used to produce abrasive wear and attrition for all specimens. Abrasion and attrition of the substrates were measured using a profilometer. Data were subjected to a 3-way analysis of variance for the 3 main factors: composite type, filler load, and wear type (alpha=.05) RESULTS: Composite wear rates were significantly influenced (P <.01) by both the type of wear and the filler amount. Abrasive wear occurred less than wear by attrition, and the heavily filled composites experienced less wear than the flowable composites. CONCLUSIONS: Results of this in vitro study suggest that highly filled microhybrid composites may have greater wear resistance for contact-supporting posterior restorations. However, in small noncontact restorations where longevity may be dictated by abrasion, flowable microfilled resins may be adequate.

Acrylic Resins↗

PubMed1999

Clinical performance of CEREC ceramic inlays: a systematic review.

OBJECTIVE: This systematic review of clinical trials seeks to identify the clinical performance of intra-coronal CEREC restorations luted with an adhesive composite technique. The focus of the review is to establish the survival rate of these restorations and to identify the factors that may cause them to fail. METHOD: A comprehensive literature search was undertaken, spanning from the year of introduction of the technology--1986 to 1997. This review identifies universal indicators of the clinical performance of intra-coronal CEREC restorations luted with an adhesive composite technique. Throughout the critical appraisal, each individual study was analysed identifying the aims, the methodology and materials used and the results obtained. RESULTS: 29 clinical reports were identified in the search. The systematic analysis reduced the focus of review to 15 studies. The data available establishes ceramic intra-coronal restorations machined by the CEREC system as a clinically successful restorative method with a mean survival rate of 97.4% over a period of 4.2 years. The review also highlights the reasons and the rates of failure for this type of restoration. The predominant reasons for failures are fracture of the ceramic, fracture of the supporting tooth, postoperative hypersensitivity and wear of the interface lute. SIGNIFICANCE: Machinable ceramics, as used by the CEREC system provide a useful restoration with a high success rate. These restorations are color stable and wear at a clinically acceptable rate. Wear of the luting composite on occlusal surfaces leads to the phenomenon of submargination. Ceramic fracture, wear at the interface and post-operative hypersensitivity remain a problem which require further investigation.

Ceramics↗

PubMed2000

[Incidence of dental, mouth, and jaw injuries and the efficacy of mouthguards in top ranking athletes].

The aim of the study was to determine the prevalence of orofacial injuries among German top athletes and their attitudes to mouthguards. A questionnaire was mailed to athletes of 10 German contact sports associations. 64.3 percent (303) of the athletes returned questionnaires. 62 percent (188) of the respondents reported that at some time they wore a mouthguard for sports participation. 47.3% (male: 57.8%, female: 38.3%) of these were currently using one. 50% of the mouthguards were custom made by dentists, and 50% were shop bought (boil-and-bite). 32 percent of the participants had, at some time during their sports career, suffered an orofacial injury. The incidence of fractured anterior upper teeth and completely knocked out teeth for athletes without mouthguards was 7 and 14, respectively. Whereas for athletes wearing mouthguards one fractured tooth was reported. Athletes with mouthguards complained of problems with speaking (19.9%) rather than of breathing (3.4%) and fitting difficulties (4.8%). Boil-and-bite mouthguards caused more fitting problems than custom-made ones. As prevalence of oral injuries in body-contact sports is high, athletes should be advised that custom-made mouthguards offer the greatest comfort, fit, durability, and protection against dental injuries.

Adult↗

PubMed1992

Abrasion: an evolutionary and clinical view.

Abrasion is the type of wear produced on the tooth by the friction of exogenous material forced over the surface by incisive, masticatory and grasping functions. It is one of the four common processes that have affected the morphology of newly erupted teeth from the time they first evolved millions of years ago. While some observers have regarded tooth reduction as pathological, there is evidence from comparative and palaeontological studies which demonstrates that these processes are an essential part of the normal, continually changing relationship between the form and function of the dentition. To understand these precise mechanisms is important if one is to replicate nature's 'intentions' in clinical dental procedures.

Adaptation, Biological↗

PubMedDate not supplied

The effect of clasp form on permanent deformation.

This study was conducted to discover whether a relationship exists between clasp width-thickness ratios and wear or deformation. Five different forms of circumferential clasps were studied. The clasps were fabricated with a 160 degree curvature around an 8-mm (diameter) cylinder and cast in Ticonium alloy. The clasps were subjected to 1500 cycles of 0.01 inch flexure. The degree of permanent deformation was not related to clasp form or width-thickness ratio. Of the five forms, only one exhibited no permanent deformation. According to Duncan's Multiple Range Test, significant differences in wear against a steel tooth model were observed among the five clasp forms evaluated (alpha = 0.05).

Chromium Alloys↗

PubMedDate not supplied

Use of interdisciplinary team approach in establishing esthetic restorative dentistry.

Managing crown lengthening in cases of attrition (wear or loss of tooth substance) and achieving desired esthetic outcomes, especially in the esthetic zone, is challenging. This case report presents an interdisciplinary approach to case management. Concomitant use of digital imaging, along with model wax-ups and surgical guide, were used to enhance patient acceptance during treatment planning and to facilitate communication and treatment implementation among dental professionals and laboratory technicians. Resulting surgical template was used for crown lengthening to apically position the gingival zenith (margin) to a predetermined level, crown preps and final restorations, respectively, ultimately improving esthetics and patient satisfaction. Supplementing esthetic treatment planning with digital imaging, model wax-ups and a surgical template allows a dentist to carry information into the mouth and incorporate it into the surgical procedure, crown preps, temps and, ultimately, the final restoration.

Adult↗

PubMed2006

Does hard insertion and space improve shock absorption ability of mouthguard?

Mouthguards are expected to reduce sports-related orofacial injuries. Numerous studies have been conduced to improve the shock absorption ability of mouthguards using air cells, sorbothane, metal wire, or hard material insertion. Most of these were shown to be effective; however, the result of each study has not been applied to clinical use. The aim of this study was to develop mouthguards that have sufficient prevention ability and ease of clinical application with focus on a hard insertion and space. Ethylene vinyl acetate (EVA) mouthguard blank used was Drufosoft and the acrylic resin was Biolon (Dreve-Dentamid GMBH, Unna, Germany). Three types of mouthguard samples tested were constructed by means of a Dreve Drufomat (Type SO, Dreve-Dentamid) air pressure machine: the first was a conventional laminated type of EVA mouthguard material; the second was a three layer type with acrylic resin inner layer (hard-insertion); the third was the same as the second but with space that does not come into contact with tooth surfaces (hard + space). As a control, without any mouthguard condition (NOMG) was measured. A pendulum type impact testing machine with interchangeable impact object (steel ball and baseball) and dental study model (D17FE-NC.7PS, Nissin, Tokyo, Japan) with the strain gages (KFG-1-120-D171-11N30C2: Kyowa, Tokyo, Japan) applied to teeth and the accelerometer to the dentition (AS-A YG-2768 100G, Kyowa) were used to measure transmitted forces. Statistical analysis (anova, P < 0.01) showed significant differences among four conditions of NOMG and three different mouthguards in both objects and sensor. About acceleration: in a steel ball which was a harder impact object, shock absorption ability of about 40% was shown with conventional EVA and hard-insertion and about 50% with hard + space. In a baseball that was softer compared with steel ball, a decrease rate is smaller, reduction (EVA = approximately 4%, hard-insertion = approximately 12%, hard + space = approximately 25%) was admitted in the similar order. A significant difference was found with all the combinations except for between EVA and hard-insertion with steel ball (Tukey test). About distortion: both buccal and lingual, distortions had become small in order of EVA, hard-insertion, and hard + space, too. The decrease rate is larger than acceleration, EVA = approximately 47%, hard-insertion = 80% or more, and hard +space = approximately 98%, in steel ball. EVA = approximately 30%, hard-insertion = approximately 75%, and hard + space = approximately 98% in baseball. And a significant difference was found with all the combinations (Tukey test). Especially, hard + space has decreased the distortion of teeth up to several percentages. Acceleration of the maxilla and distortions of the tooth became significantly smaller when wearing any type of mouthguard, in both impact objects. But the effect of mouthguard was clearer in the distortion of the tooth and with steel ball. Considering the differences of mouthguards, the hard-insertion and the hard + space had significantly greater buffer capacity than conventional EVA. Furthermore, hard + space shows quite high shock absorption ability in the tooth distortion. Namely, hard + space has decreased the distortion of teeth up to several percentages in both impact objects.

Acceleration↗

PubMedDate not supplied

Investigation of human enamel wear against four dental ceramics and gold.

OBJECTIVES: This in vitro study compared the wear of enamel against aluminous porcelin, bonded porcelain, low fusing hydrothermal ceramic, feldspathic machinable ceramic, and cast gold. METHODS: Fifty pairs of tooth-material specimens were tested in a dental wear machine, under a standard load (40 N), rate (80 cycles min-1) and for 25,000 cycles in distilled water. The amount of wear was determined by measuring the height loss of the tooth, and the depth of wear track of the restorative materials. RESULTS: There was a significant difference in wear among the groups for both enamel and materials (p < 0.001). Follow-up comparisons (95% CI significance level) showed that gold caused significantly less enamel wear than all ceramics tested. The amount of enamel wear in the aluminous and bonded porcelain groups was significantly higher than with the hydrothermal and machinable ceramic groups. There was no significant difference between the amount of enamel wear produced by the aluminous and bonded porcelains nor between that produced by the hydrothermal and machinable ceramics. Furthermore, the wear of the aluminous and bonded porcelains was significantly greater than that of the hydrothermal ceramic, the machinable ceramics and gold. No significant difference in wear was found between aluminous and bonded porcelains, hydrothermal and machinable ceramics, or between machinable ceramic and gold. However, the hydrothermal ceramic had significantly greater wear than gold. CONCLUSIONS: It was concluded that the hydrothermal and the machinable ceramics were significantly less abrasive and more resistant to wear than the conventional aluminous and bonded porcelains. Gold was the least abrasive material and most resistant to wear, although the difference in wear between the machinable ceramic and gold was not statistically significant.

Aluminum Oxide↗

PubMed1999

Width/length ratios of normal clinical crowns of the maxillary anterior dentition in man.

The purpose of this investigation was to analyze the clinical crown of the 3 tooth groups of the maxillary anterior sextant of the permanent dentition of normal subjects with respect to (i) width, length and the width/length ratios and (ii) determine if there is a correlation between tooth dimensions or tooth group ratios and subject height. Subjects (> or = 20 y.o.) were recruited for this study if (i) the free gingival margin on the facial surface of teeth in the maxillary sextant was positioned apical to the cervical bulge, (ii) there was no evidence of attachment loss; as determined by lack of a detectable CEJ and (iii) the marginal tissue was knife edged in form, firm in consistency and coral pink in color. Teeth were excluded if (i) there was evidence of gingival alteration, i.e., gingival overgrowth/hyperplasia, inflammation, altered passive eruption, attachment loss, gingival recession or history of periodontal surgery, or (ii) there was evidence or history of incisal edge/proximal tooth alteration as in, i.e., restorative intervention, traumatic injury or occlusal wear into dentin. At least 1 suitable tooth from each tooth group of the maxillary anterior dentition had to be present. A maxillary impression was taken and poured in yellow die stone. The widest mesial-distal portion and the longest apical-coronal portion of the test teeth were measured. Gender, ethnicity and subject height (SH) were recorded for each participant. Due to a limited ethnic diversity only data from the Caucasian group were analyzed. The mean coronal tooth width (mm) of males versus females was CI: 8.59 versus 8.06, LI: 6.59 versus 6.13 and CA: 7.64 versus 07.15. The mean coronal tooth length (mm) of males versus females was CI: 10.19 versus 9.39, LI: 8.70 versus 7.79 and CA: 10.06 versus 8.89. All width and length measures were significantly greater for males than for females. The mean coronal tooth width/length ratios for males versus females was CI: 0.85 versus 0.86, LI: 0.76 versus 0.79 and CA: 0.77 versus 0.81. A comparison between genders of the width/length ratios of the CI and LI were found not to differ, however the CA ratio for females was significantly greater than for males. A statistically significant difference was found to exist between the mean (cm) SH for males versus females: 181.2 versus 164.0. A positive correlation (p < or = 0.0001 to 0.0691) was found to exist between tooth group width/height ratios within genders. No significant correlation was found between any of the tooth dimensions or tooth group ratios and SH. The results of this study indicate that within male and female Caucasians, the mean width/length ratio of the maxillary 3 anterior tooth groups is 0.81. As well, within both genders there is a positive correlation between tooth group width/length ratios. The significance of these findings with respect to periodontal mucogingival plastic surgical procedures is discussed.

Adult↗

PubMed1979

Characterization of wear of tungsten carbide burs.

On the basis of this study, the following conclusions can be made:--Although the primary cause of the diminution of cutting efficiency when composite restorations are cut is due to abrasion, a secondary cause is the adhesion of the melted resin to the flutes.--Amalgams and tooth structures cause significantly less wear to burs than composite restorations.--The design of burs currently used is probably a poor choice to remove composite restorations.

Carbon↗

PubMedDate not supplied

Tissue changes in the rabbit periodontal ligament during orthodontic tooth movement.

In this (semi) quantitative animal study the reaction of the periodontal ligament (PDL) to experimental tooth movement is described. To this end, rabbit first incisors were moved sideways with helical torsion springs for periods varying from 3-24 hours. The initial force of the springs was 50 gf. The histomorphology of the PDL was studied in 5 microns thick plastic sections. Comparison with control animals and animals wearing passive springs showed that tooth movement leads to an increased trauma in the PDL within only a few hours. This trauma is characterized by hyalinization, tears and ruptures in the fibres and blood vessels, and by the presence of extravascular erythrocytes and pyknosis. Tissue damage significantly increased with time. After 24 hours of tooth movement, the PDL fibers are compressed or stretched in 68% of the sections and the blood vessels in the PDL are compressed or stretched in 62% of the sections. Even in the controls, more than 15% of the sections displayed slightly stretched or compressed fibers, and about 10% showed slightly compressed or stretched blood vessels. This indicates that some damage is regularly present in a normally functioning PDL. Increases in the percentage of sections with blood vessel compression are found in all groups wearing passive springs, especially after 6 hours. A high concordancy in compression and tension patterns of blood vessels and fibers is present in 83% of the sections. Pyknotic cells are practically confined to areas with compressed PDL fibers in rabbits wearing active springs. Extravascular erythrocytes were found in sections with all types of fiber patterns. A significant majority of extravascular erythrocytes, however, was found in areas with compressed fibers.

Animals↗

PubMed1998

A study of retentive filler and its use in dentistry.

OBJECTIVE: The purpose of this study was to develop a fine compound inorganic filler with special surface microstructure (called retentive filler or RF) and to investigate its use in composite resin and synthetic resin teeth. METHODS: Barium silicate glass and fine silicon dioxide or barium silicate glass were mixed and sintered, then dispersed and classified by sedimentation. The surface microstructure and the particle size distribution of retentive filler were surveyed, and the mechanical properties of the composite resin and the resin tooth material reinforced with RF were tested. RESULTS: Scanning electron microscopy showed that the surface of RF particles is distinguished for its retentive contour microstructure. The particle size of RF is smaller than 3 microns. The mechanical properties of composite resin reinforced with RF are better than that of composites containing normal fillers, and the wear resistance of the resin tooth material containing RF is better than that of normal synthetic resin. CONCLUSIONS: The RF can be successfully prepared by the technological process in this study. Because of the special surface microstructure, RF has a good bonding to the resin matrix. The testing results suggest that it is feasible to improve the mechanical properties, especially the wear resistance of the composite resin and resin teeth, by using retentive filler.

Barium Compounds↗

PubMed1989

[Erosions of hard tooth substance].

Lemon juice was applied to intact and eroded tooth surfaces in vivo to demonstrate the development of erosions based on morphological changes. Under the influence of the fruit acid the protecting pellicles are removed and the enamel demonstrates the typical etch lesion with a honeycomb surface structure. In the dentin the acid works mainly on the peritubular area. Abrasive brushing techniques wear down the already damaged tooth surfaces.

Acid Etching, Dental↗

PubMedDate not supplied

Two-body wear of dental composites under different loads.

PURPOSE: Although dental composites are excellent for restoring the appearance of natural tooth tissues, their relatively poor resistance to wear, especially in approximal and occlusal contact areas, is still a major source of concern. The aim of this research was to study a basic wear mechanism, under 2-body wear conditions, that may be integrated into our understanding of the in vitro and in vivo wear behavior of dental composites. MATERIALS AND METHODS: An in vitro 2-body wear test was conducted on 2 selected ultrafine compact-filled dental composites under different magnitudes of sinusoidal cyclic load. The wear surfaces and cross sections of the wear layers were assessed using scanning electron microscopy (SEM) to explore the nature of the wear pattern of the dental composites under cyclic loading conditions. RESULTS: The wear losses of both composites increased with load. SEM analysis of wear surfaces and subsurface sections indicated that the composites tested displayed different wear mechanisms from low to high loads. An explanation for the wear pattern is proposed based on the observed wear behavior. CONCLUSION: The in vitro wear pattern of the ultrafine compact-filled dental composites tested is closely related to the applied load. Although the wear loss increased in a roughly linear relationship with applied load, the underlying wear mechanism involved may experience a significant change from low to high load conditions during wear.

Bisphenol A-Glycidyl Methacrylate↗

PubMed2005

A comparison of post-operative complications following wisdom tooth surgery performed with sterile or clean gloves.

This randomised prospective study aimed at evaluating possible differences in the post-operative complication rate following lower wisdom tooth surgery performed with either sterile or clean surgical gloves. The microbiological profiles of the tooth sockets and glove surfaces were also evaluated and compared. A total of 275 ASA I, non-smoking and non-drinking patients consented to be randomly assigned into two groups for lower wisdom tooth surgery, performed by operators wearing either sterile or clean gloves. All the patients returned for a post-operative assessment visit one week later. An additional 40 patients were recruited and randomised into the sterile glove group (n = 20) or the clean glove group (n = 20) for the microbiology study. Specimens were taken from the glove surfaces and the post-operative socket wounds during wisdom tooth surgery. This clinical trial showed no significant difference between the sterile and clean glove groups in the incidence of acute inflammation, acute infection and dry sockets in the wounds. No single peri-operative factor had a statistically significant effect on post-operative pain intensity. Most of the bacterial isolates from the clean gloves were Gram-positive cocci or spore-forming bacilli. The total number of colony forming units and the variety of bacterial isolates from the socket wounds in the sterile and clean glove groups were similar. The study concluded that there was no advantage in using sterile surgical gloves rather than clean gloves to minimize post-operative complications in wisdom tooth surgery. There was also no apparent relationship between the bacteria contaminating the clean glove surfaces and those isolated from the socket wounds.

Adolescent↗

PubMed2007

Continuity or discontinuity of the life-style in central Italy during the Roman Imperial Age-Early Middle Ages transition: diet, health, and behavior.

Dento-alveolar pathologies and alterations (dental wear, caries, abscesses, ante mortem tooth loss (AMTL), calculus, hypoplastic defects, and chipping) and skeletal markers of health (cribra orbitalia and periostitis) were analyzed in two skeletal samples from the necropolises of Quadrella (I-IV c. AD) and Vicenne-Campochiaro (VII c. AD) in the Molise region of central Italy. The aim was to determine if the Roman Imperial Age-Early Middle Ages transition characterized by political, socioeconomic, and cultural transformations affected the biology of these populations, particularly their alimentation and health status. The frequencies of caries and AMTL, similar in the two samples, suggest a high consumption of carbohydrates. The higher levels of heavy wear, calculus, and interproximal chipping in the Vicenne population indicate a greater use of fibrous foods (both meat and others), in line with the dietary model of Germanic peoples. Health conditions do not appear to have been good in either period, as shown by the high frequencies of linear hypoplasia and the presence of cribra orbitalia and periostitis. The diet of the individuals buried with horses of the Vicenne population did not differ from that of the rest of the population, whereas there were evident differences in the use of the teeth for nonmasticatory activities among these individuals. Therefore, from the point of view of alimentation and health status, the profound socioeconomic and cultural transformations during the Late Antiquity-Early Middle Ages transition do not seem to have been translated into a true discontinuity of the two Molisan populations.

Diet↗

PubMed1983

Relationships between oral parafunctions and functional disturbances and diseases of the stomatognathic system among children aged 7-14 years.

Data from an interview and clinical examination in a study of 440 randomly selected school children were analyzed with regard to relationships between signs and symptoms of functional disturbances and diseases in the stomatognathic system. A correlation was found between reported clicking sounds from the temporomandibular joint (TMJ) and pain when opening the mouth wide. Children who had been treated orthodontically or who were undergoing such treatment did not differ from other children in the frequency of signs and symptoms. Correlations were found between recurrent headaches and tenderness in TMJ and TMJ muscles. Reported pain in the temple region was also correlated to tenderness in the TMJ and TMJ muscles. Further correlations were found between recurrent headaches and oral parafunctions such as lip-cheek-biting and nail-biting and also among nail-biting, tooth clenching, tooth-grinding, and frontal dental wear. Children who reported oral parafunctions had more frequent interferences in RP and tenderness in TMJ muscles. There were correlations between irregular movements of the lower jaw and interferences in RP as well as mediotrusion interferences. Finally, a strong correlation was found between tenderness of the TMJ (laterally and posteriorly) and tenderness of the TMJ muscles.

Adolescent↗

PubMed1986

A conservative alternative to lower posterior bridges replacing mandibular first molars.

The permanent first molars erupt at the age of six years old. These teeth are most prone to dental caries and are often extracted at an early age because of dental decay. The conventional approach to replace these extracted teeth include fixed bridge, removable side plate and removable partial denture. In suitable cases, spaces created by the missing permanent first molars can be closed by the use of orthodontic appliances thereby avoiding the unnecessary sacrifice of sound tooth structure or the discomfort of wearing removable partial prosthesis.

Adult↗