PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “DENTAL RESTORATION, PERMANENT”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 379 records · Page 21Linked to original sources
PubMed1998

The effect of stiffness on the localization of tensile stress at the surface of bonded posterior restorations.

OBJECTIVES: The aim of this study is to assess the distribution of tensile stress under the conditions representative of tooth-food contact in a restored posterior tooth. The ideal stiffness for a bonded restoration will be predicted. METHODS: A two-dimensional plane-strain finite element representation of a restored first maxillary molar is created. The restoration with Class I/II bucco-lingual geometry is assigned a range of Young's moduli (E = 10-80 GPa), representative of the range of materials available. In addition, a hypothetical multi-phase model, in which stiffness is gradually increased from the intercuspal concavity to the adjacent enamel, is also created. A food particle is modeled and pushed close to the interface onto the site of (1) intact enamel and (2) restored surface. RESULTS: For all single-phase models tested, the magnitude of tensile stress at the surface is far greater than that present elsewhere in the tooth. However, the exact position and magnitude of the maximum tensile stress varied according to the modulus assigned to the restoration and the position of load. The results of the model imply that interfacial problems are likely in low-modulus restorations (E = 10-20 GPa), whereas stress-related problems could occur in the intercuspal concavity of high-modulus restorations (E = 40-80 GPa). Of all the single-phase models, tensile stresses are lowest when the Young's modulus assigned to the restoration is 30 GPa. These tensile stresses are reduced in the multi-phase model. SIGNIFICANCE: Given the limitations of the model, the results indicate that the most suitable modulus for a single-phase posterior bonded restoration is around 30 GPa. Such a modulus is approached in compact-filled composites. In addition, the highly desirable dissipation of load in the multi-phase model should warrant further investigation. It is suggested that the use of an incremental filling technique with region-specific proportions of hard-filler could be one way forward.

Computer Simulation↗
PubMed1998

Immediate versus one-month wet storage fatigue of restorative materials.

Immediate finishing is a highly desirable property of restorative materials. In general, the resin composites, the polyacid-modified resin composites and resin-modified glass-ionomers are finished immediately after light-curing. For the conventional glass-ionomers a waiting period of 24 h is recommended. Therefore, the objective of this study was to investigate whether immediate finishing and application of cyclic loading under water spray on resin-modified glass-ionomers, a conventional glass-ionomer, a polyacid-modified resin composite and a resin composite are reflected in their Young's modulus and fatigue resistance after 1-month wet storage compared with a control group that could mature untroubled for 1 month. From this study, it could be concluded that there is a material-dependent response on immediate finishing. For the conventional glass-ionomer, the waiting period of 24 h is highly advisable. The resin composite suffered more than the other test materials. A second statement is that one must be cautious by the extrapolation of findings obtained on quasi static tests (Young's modulus) towards dynamic properties (flexural fatigue limit).

Biocompatible Materials↗
PubMed2001

A comparison of the mechanical behavior of posterior teeth with amalgam and composite MOD restorations.

OBJECTIVE: To compare the mechanical behavior, and infer differences in fracture resistance, of mandibular molars with amalgam and composite MOD restorations to that of an unrestored molar. METHOD: Finite element models were developed for an unrestored molar and molars with MOD amalgam and composite restorations. The location and magnitude of maximum principal stress resulting from simultaneous mechanical and thermal loads were determined for each molar using a series of designed experiments. An analysis of variance was conducted with the components of stress to distinguish the relative influence of oral parameters and restoration on the stress distribution in each molar. RESULTS: The maximum principal stress in the unrestored molar was the largest of all three molars examined and occurred within the dentin along the pulpal wall. Maximum principal stresses in the molars with amalgam and composite restorations both occurred along the cavosurface margin. Maximum principal stresses in the molar with amalgam restoration occurred at the pulpal floor and lingual wall junction and resulted from large occlusal loads. Although occlusal loading had minimal effects on the stress distribution within the molar with composite restoration, low oral temperatures were responsible for the maximum principal stresses, which were found at the lingual margin and occlusal surface junction. CONCLUSION: There was no significant difference in the magnitude of maximum stress that occurred in the molars with amalgam and light curing composite restorations. However, the location and orientation of maximum stress in the restored molars were largely dependent on the restorative material. Although clinical studies report that tooth fracture occurs predominately to restored molars, the unrestored molar experienced the highest stress in this investigation. Therefore, the reduction in fracture resistance of restored posterior teeth appears to result from changes in the location of maximum stress resulting from mastication and temperature changes.

Analysis of Variance↗
PubMedDate not supplied

Polymerization contraction stress in dual-cure cements and its effect on interfacial integrity of bonded inlays.

OBJECTIVES: To compare the polymerization contraction stress of resin cements in dual-cure and self-cure modes, and verify its effect on microleakage and gap formation in class I cavities restored with porcelain inlays. METHODS: Dual-cure cements (Calibra, Choice and RelyX ARC) were monitored for contraction stress during 30 min in the tensilometer, in the presence or absence of photo-activation. Microleakage was evaluated in porcelain inlays bonded to cavities prepared in bovine incisors, combining the same adhesive (One-Step) with each of the cements in both activation modes. Epoxy replicas of the sectioned specimens were analyzed in the SEM to determine the percentage of discontinuous margins. RESULTS: The stress developed in dual-cure mode was higher than in self-cure mode for all cements. In self-cure mode, no significant difference in stress was found among materials. Choice and RelyX ARC showed higher microleakage in dual-cure mode than in self-cure mode. Calibra did not show a significant difference in microleakage between activation modes. Contraction gap results showed wide variations, and no significant differences were detected among the groups. Gaps occurred more often in dentin, with an overall average of 22 +/- 17.5%. CONCLUSIONS: The higher stress generated in dual-cure cements subjected to photo-activation may lead to higher marginal leakage. In the confinement condition represented by the class I inlay, even the lower contraction stress of the cements in self-cure mode had enough magnitude to disrupt the bonding to dentin.

Animals↗
PubMed2003

Cuspal movement and microleakage in premolar teeth restored with a packable composite cured in bulk or in increments.

INTRODUCTION: The aim of this study was to investigate the effect of two novel curing systems (a plasma arc light, and a 'turbo-boosted' conventional curing light) on cuspal movement and gingival microleakage of 'packable' resin-based composite (RBC) restorations placed in extracted maxillary premolar teeth. MATERIALS AND METHODS: Forty sound extracted upper premolar teeth were subjected to standardised preparation of a large mesio-occlusal-distal cavity before restoration with a RBC. Four curing regimens were used. Either the RBC was placed in bulk and light-cured in one increment using (a). the plasma arc light; (b). the 'turbo-boosted' curing light, or the RBC was placed in eight increments using (c). the plasma arc light; (d). the 'turbo-boosted' curing light. A deflection measuring gauge allowed a measurement of cuspal deflection at each stage of polymerisation. Restored teeth were thermocycled before immersion in a 0.2% basic fuchsin dye for 24 h. After sagittal sectioning of the restored teeth in a mesio-distal plane, the sectioned restorations were examined to assess cervical microleakage. RESULTS: Cuspal deflection measurements were significantly increased when the 'turbo-boosted' halogen curing light was compared with the plasma arc light. Total mean cuspal deflection measurements obtained with incremental cure were significantly increased compared with bulk cure for both light sources. Gingival microleakage for bulk restored teeth was significantly increased compared with teeth restored incrementally. Incremental restoration with the plasma arc light had significantly increased gingival microleakage compared with the 'turbo-boosted' halogen curing light. CONCLUSIONS: The packable composite tested could not be cured adequately to a depth of 5 mm with the plasma arc light within the specified irradiation time. Under the test conditions of the current investigation, bulk curing only appeared to be practical with the high intensity halogen light (40 s activation). Incremental build-up and polymerisation optimised marginal seal for the high intensity halogen light but led to greater cuspal deflection.

Bicuspid↗
PubMed2003

Mercury generation potential from dental waste amalgam.

OBJECTIVE: The main objective of this study was to quantify the total amount of amalgam used in dental offices in the state of Illinois and to estimate the fractions of amalgam waste material generated during dental procedures. A second objective was to estimate the fractions of non-contact, contact, and tooth retained amalgam through an in vitro study. METHODS: The collection system consisted of containers placed in six dental offices and clinics to collect the material from the in-line trap (contact amalgam) and the excess dental amalgam not placed into the oral cavity (non-contact amalgam). In order to have comparable results, the data was adjusted by the number of dental chairs being used and the number of working days. RESULTS: The range for the non-contact amalgam was from 0 to 102 g, and for the contact amalgam, from 2 to 16 g. The median estimate of non-contact amalgam generated from the 6 dental offices was 421 mg/day/chair, whereas the median estimate of contact amalgam was 64 mg/day/chair. For the in vitro study, 40 one and two surface amalgams (bicuspids and molars), was distributed as follows, 46+/-20% in the tooth, 43+/-19% as non-contact amalgam, and 11+/-4% as contact amalgam. CONCLUSIONS: Based on survey data from the ADA concerning the number of working days per year, the number of practicing dentists, a 50%, by weight, mercury content in amalgam, and the generation estimates from this project, it was estimated that the practicing dentists in the State of Illinois (6455) have the potential to generate 947 kg of non-contact mercury per year, which is recyclable, and 144 kg of contact mercury which has the potential to be discarded in the environment, or be partially recycled. If this approach is applied to the total population of practicing dentist in the United States (123,641), then 18,159 kg of recyclable, non-contact mercury may be generated per year, whereas 2763 kg of contact mercury may be discarded in the environment, or be partially recycled.

Dental Amalgam↗
PubMedDate not supplied

Effect of dentine depth on the fracture toughness of dentine-composite adhesive interfaces.

OBJECTIVES: The fracture toughness test was recently introduced as a clinically relevant method for assessing the fracture resistance of the dentine-composite interface. The objective of this study was to evaluate the effect of dentine depth on the interfacial fracture toughness test of several dentine-composite interfaces using some new proprietary dentine bonding agents. METHODS: Miniature short rod fracture toughness specimens containing a chevron-shaped dentine-composite-bonded interface were prepared for each group (n = 12). Six different dentine bonding agents and two dentine depths were the variables assessed at the dentine-composite interfaces. After 24 h at 37 degrees C in water, the specimens were tested by loading at 0.5 mm/min in the Instron Universal Testing Machine. The interfacial KIC results were analysed by ANOVA, unpaired Student's t-tests and Fisher's LSD test (P < 0.05). RESULTS: The interfacial KIC results in MN.m-3/2 (S.D.) on superficial and deep dentine, respectively, were: All-Bond 2, 0.80 (0.21), 0.44 (0.13); Bond-lt, 0.75 (0.20), 0.38 (0.19); Prime and Bond, 0.56 (0.11), 0.28 (0.10); Scotchbond Multi-Purpose, 0.45 (0.23), 0.26 (0.15); One-Step and OptiBond, insufficient results due to premature specimen failures. CONCLUSIONS: The results from this study should contribute to the development of the fracture toughness test as a method for assessing the integrity of the dentine-composite interface. The interfacial fracture toughness test determined significant differences among the different dentine bonding agents and between the superficial and deep dentine substrates. The dentine bonding agents showed significantly reduced interfacial fracture toughness results when bonding to deep versus superficial dentine.

Adhesives↗
PubMed1997

Polymerization shrinkage and polymerization shrinkage stress in polymer-based restoratives.

OBJECTIVES: This paper is intended to contribute to the recognition and understanding of problems related to polymerization shrinkage. DATA SOURCES: Scientific publications of relevance with regard to this subject were critically reviewed. STUDY SELECTION: The dimensional changes which develop during the curing of resin composites and glass polyalkenoate cements are studied, with special reference to methods of determining shrinkage, shrinkage stress and stress relief. CONCLUSIONS: As no method for handling the adhesive restorative materials has yet been described which guarantees a leakproof restoration, the practitioner has to accept the problem of polymerization shrinkage and destructive shrinkage stress. Only a proper understanding of the mechanisms that cause these problems and the techniques that may reduce their effects will enable the practitioner to derive maximum benefit from the application of resin composites and glass polyalkenoate cements in restorative dentistry.

Composite Resins↗
PubMedDate not supplied

Effect of restored and unrestored non-carious cervical lesions on the fracture resistance of previously restored maxillary premolar teeth.

OBJECTIVES: The effect of non-carious cervical lesions (NCCL) on tooth fracture resistance has not previously been investigated. The aims of this in vitro study were to examine the fracture resistance of a group of extracted maxillary premolar teeth with mesio-occlusal-distal (MOD) restorations of amalgam, and restored or unrestored simulated NCCL. METHOD: Forty sound maxillary, premolar teeth were divided at random into four groups, each of 10 teeth, which were fixed crown uppermost and long axis vertical in stainless steel moulds. Groups 1,2,3 and 4 were prepared with standardized parallel-sided MOD cavities, then restored with amalgam. Groups 1, 2 and 3 were further prepared with standardized NCCL. The NCCL in Group 1 were restored using a resin-modified polyalkenoate (glass-ionomer) cement, and the NCCL in Group 2 were restored with an adhesive composite resin system. The NCCL in Group 3 were left unrestored. The specimens were loaded compressively at 1 mm min-1 using a universal testing machine. RESULTS: Mean fracture loads (KN) of 1.08, 1.03, 0.98 and 1.14, respectively, were recorded for Groups 1, 2, 3 and 4. Two-way ANOVA and Scheffe's Multiple Range Test showed no statistically significant difference between the groups. CONCLUSIONS: It is concluded that the presence of a standardized NCCL in an extracted maxillary premolar tooth does not reduce the fracture resistance of the tooth when loaded compressively at 1 mm min-1. The restoration of NCCL with the materials tested did not result in an increase in the fracture resistance of the previously restored premolar teeth, when loaded compressively at 1 mm min-1.

Analysis of Variance↗
PubMed1998

Bond strength of repaired anterior composite resins: an in vitro study.

The objectives of this study were to investigate the repair potential of two commercially available composite resins in terms of bond strength, and the effectiveness of two commercially available adhesive systems used as intermediary materials in the repaired specimens. The repair strength of Helio Progress (HP) and Herculite XRV (XRV) was tested using two bonding agents: DenTASTIC (DT) and All Bond 2 (AB2). The effect of surface abrasion of specimens and the effect of time on repair strength were also investigated. Surface abrasion significantly improved the bond strength (P < 0.001) and the use of bonding agents further enhanced bond strength but not significantly. Use of bonding agents alone improved the repair bond strength significantly (P < 0.001). Repair of HP with HP after surface abrasion and application of DT produced the highest repair bond strength which was 99% of the cohesive strength of the control (unrepaired) specimens. Although there were some differences in the bond strength over the time period of the study (one month) none of these was statistically significant. It is concluded that surface abrasion coupled with the application of bonding agent produces the highest repair strength. It seems likely that clinically acceptable bond strengths are possible after repair of anterior composite resins.

Composite Resins↗
PubMedDate not supplied

Cusp reinforcement by bonding of amalgam restorations.

The purpose of the present study was to assess the effectivenes of several adhesives in bonding amalgam in order to recover tooth stiffness. A non-destructive experimental methodology was adopted, using strain gauges bonded to the midbuccal surfaces of 40 teeth, with sequential evaluation of loaded intact, prepared and restored stages of the same tooth. Continuous strain measurement as a function of the applied load was acquired by A/D equipment and a data acquisition programme. The strain-force behaviour of the sound teeth under non-axial force up to 97.5 N served as the baseline. The five experimental groups (8 x 5) consisted of control (no adhesive) and four different adhesives. One-way analysis of variance with repeated measures was calculated for the deformation ratio, relative stiffness and recovery values. Reductions in tooth structure by cutting a mesio-occlusal-distal preparation, width one-third intercuspal distance, resulted in 39-52% loss of buccal cusp stiffness. Non-bonded amalgam produced negligible increase (5%) in the stiffness recovery values of the buccal cusps. The adhesives splinted the cusps together, thereby decreasing cuspal flexure and increasing relative stiffness values. Recovery values obtained ranged from 39% to 61%. Assuming that cusp fracture occurs as a result of brittle tooth structure fatigue, amalgam adhesives may contribute to the strengthening of weakened cusps.

Adhesives↗
PubMed1999

Maximising the fracture resistance of dentine-bonded all-ceramic crowns.

Results of previous studies have indicated that the use of different ceramic materials and differing bonding/luting systems may affect resistance to fracture of teeth restored with dentine-bonded crowns. It is the purpose of this investigation to examine in vitro fracture resistance of dentine-bonded ceramic crowns, using materials in combination which have demonstrated increased fracture resistance when they are used individually. Ten sound maxillary premolar teeth were selected. These teeth were prepared for full crowns in a similar manner to previous, related studies. Standardised crowns were constructed in a leucite reinforced ceramic (Empress: Ivoclar-Vivadent, Liechten-stein) and placed using a dentine-bonding system and resin-composite luting system (3M; St. Paul, MN, USA). Compressive force was applied through a 4 mm diameter steel bar applied to the occlusal surface of the restored specimens. A mean fracturing force of 1.67 kN was recorded, statistical analysis indicating that this was significantly greater than any previously used combination of ceramic material and bonding/luting system, and greater than a group of sound, unrestored teeth. The fracture resistance of teeth restored in vitro by dentine bonded crowns may be enhanced by the combination of the materials described.

Aluminum Silicates↗
PubMed2002

Hardness and in vitro wear of a novel ceramic restorative cement.

The aim of the present work was to compare a new ceramic restorative cement for posterior restorations, DoxaDent, with other types of tooth-colored materials for direct use as regards hardness and in vitro wear. Four hybrid resin composites, one polyacid-modified resin composite, one resin-modified glass ionomer cement, one conventional glass ionomer cement, one zinc phosphate cement, an experimental version as well as the marketed version of the ceramic restorative cement, were investigated. Hardness of the materials was tested with the Wallace indentation tester and wear was tested with the ACTA wear machine. All tests were carried out on 2-wk-old specimens. DoxaDent was as hard as the zinc phosphate cement and the hardest resin composite. The ceramic restorative cement wore significantly more than the resin composites, the same as the zinc phosphate cement, and less than the glass ionomer cements. No correlation between hardness and wear was found. It can be concluded that the ceramic restorative cement is a rather hard material but with a relatively low wear resistance.

Aluminum Compounds↗
PubMed2000

Impact strength of teeth restored by fragment-bonding.

The objective of this in vitro study was to investigate the impact strength of anterior teeth that have been fractured and restored by bonding with a dentin-bonding agent and a composite resin. Twenty sheep central incisors were divided into two groups, 10 in each. One group (intact teeth) served as the control and the teeth in the other group were fractured and then bonded with a bonding agent and a low-viscous composite resin. The specimens were tested in a modified impact-testing machine (pendulum type). The mean impact strength of the intact teeth was 30.6 +/- 2.16 KJ/m2 and of the bonded teeth was 30.2 +/- 1.86 KJ/m2. Statistics revealed that the two means were not significantly different. The results related well with the fracture strength obtained by loading intact and bonded teeth at constant but low speed until fracture. It was concluded that bonding fragments to the remaining tooth structure may restore the tooth to its original strength, measured at modest velocities of the applied force. In other words, reattaching the original coronal fragment of traumatised fractured anterior teeth restored with One-Step dentin bonding system and AEliteflo composite resin would withstand a second trauma to the same extent as intact teeth.

Acid Etching, Dental↗
PubMed2000

Perceptions of general dental practitioners of a local secondary care service in restorative dentistry.

AIM: A major role of the hospital based secondary care service in restorative dentistry is to accept referrals in order to formulate treatment plans. The aim of this survey was to improve service provision at Newcastle Dental Hospital by establishing baseline quality perceptions from referring general dental practitioners (GDPs). METHOD: A postal questionnaire was sent to 393 randomly selected local GDPs, with a response rate of 67%. RESULTS: Results indicated great demand for advice and treatment which was higher than expected for temporomandibular joint problems. 42% of GDPs felt that treatment plans were not helpful and the period of waiting for a response following consultation too long. The reasons for this perception are discussed. CONCLUSIONS: The need for better communication between primary and secondary care was highlighted, as was the distinct preference of GDPs for hospital consultants rather than registered specialist practitioners to carry out specialist treatment.

Attitude of Health Personnel↗
PubMed2002

Factors associated with amalgam restorations in Taiwan.

OBJECTIVE: This study investigated the prevalence of and factors associated with amalgam restorations of posterior teeth in Taiwan. METHOD: The authors analyzed the dental data regarding direct restorations of posterior teeth from the National Health Insurance Research Database of 1997, which was the first nationwide data available. The chi-square test and analysis of variance was used to compare the characteristics of the teeth, patients, dentists, and dental treatment settings between amalgam and composite restorations. The multivariate analysis was applied to obtain the Generalized Estimating Equation estimation for associations of multiple factors with amalgam restorations, taking into account the intra-individual correlation of teeth restored. RESULTS: Amalgam was used in 53.3% of the direct restorations of posterior teeth. When all the important factors were assessed simultaneously, characteristics significantly associated with more amalgam restorations were: dentists aged 43 years and above, patients aged 1-22 years, primary molars, two- or three-surface cavity, regions with higher number of population served per dentist, and dental clinic. CONCLUSION: Doctors' age, patients' age, type of dental treatment settings, population served per dentist, type of tooth, and number of surfaces restored were significantly associated with amalgam restorations in Taiwan.

Adolescent↗