Biomedical subjects
Publications and source records attributed to F J Roeters.
Today, extensive and generalized tooth wear is often a reason for restoring the occlusion. Adhesive techniques and direct composite restorations can reduce the need for more expensive indirect restorations. In this article the advantages and disadvantages of the direct and indirect techniques are discussed. Furthermore, the treatment sequence for direct restorations is described and illustrated by some case-reports.
The direct composite veneer restoration is a minimal invasive tooth-saving and relatively cheap technique suitable to improve the esthetics of the dentition in many cases. In this article factors in influencing the selection of materials are discussed. Furthermore, advantages and disadvantages of the direct composite veneer are listed and some cases are presented.
The direct composite crown is a restoration replacing the original toothcrown in form and function. It can be an alternative for indirect gold or porcelain restorations if the oral health condition is not stable, if indirect restorations require a high biological price or if financial resources are limited. The longterm durability of these restorations is still unknown. As a direct composite crown can be considered as minimally invasive and can be easily replaced by an indirect restoration if needed, there are hardly any contra-indications for its use.
Sealing of pits and fissures depends on patient- and tooth factors. Prevention of occlusal carious is indicated for children with a high caries risk and especially when the morphology makes teeth more susceptible for developing caries (deep pits and fissures). Good occlusal caries diagnosis is difficult and a golden standard does not exist. When sealing of pits and fissures is indicated a preventive or a therapeutic approach can be chosen. A generally accepted guideline for sealing is still missing. Every approach has its advantages and disadvantages and depends on the individual operator.
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OBJECTIVES: Bases are used in restorative dentistry for several reasons (i.e. isolation, elimination of undercuts, etc). Glass ionomers are the standard materials used as bases for porcelain inlays, despite the disadvantages of their mechanical properties. An alternative basing material is composite: a generous layer of posterior composite is cured and shaped in the cavity before an impression is taken. The composite basing technique has several clinical advantages. The aim of this study was to investigate the effect of the thickness of a composite base on the bulk fracture resistance of industrial porcelain, and to describe the procedure. METHODS: Fifteen porcelain (P) and 15 composite (C) bars, 1-, 2-, and 3-mm thick were joined to form 15 C/P bars, all 4-mm thick. Three groups were created: C 1 mm/P 3 mm (group 1), C 2 mm/P 2 mm (group 2), and C 3 mm/P 1 mm (group 3). The pairs were joined using Twinlook cement, subjected to a three-point bending test and loaded to fracture. The beam theory was used to support and explain the results. RESULTS: The fracture load means were: group 1, 197.7 +/- 18.7 N; group 2, 234.3 +/- 63.3 N, group 3, 336.3 +/- 31.3 N. Group 3 was significantly stronger than group 1 (P = 0.01) and group 2 (P = 0.03). Groups 1 and 2 were not statistically different. CONCLUSION: Composite basing is a tissue conserving method which may significantly increase the resistance to bulk fracture of adhesive porcelain inlays.
INTRODUCTION: Clinical studies on the quality of Class II amalgam and resin composite restorations frequently report defective cervical margins. AIM: The aim of this study was to evaluate the quality of the approximal margins of Class II resin composite restorations placed in vivo using various application techniques and adhesive systems. MATERIALS AND METHODS: Class II restorations were placed in premolar teeth in vivo, using different adhesive systems and application techniques. After extraction of the teeth, the restorations were evaluated radiographically and by SEM. RESULTS: One-hundred and forty-four resin composite Class II restorations were evaluated. According to the radiographs, 4% of the restorations were overfilled and 33% were underfilled. SEM pictures revealed that 43% of the restorations were overfilled and 25% underfilled. Thirty-two per cent of the restored teeth showed a flash of bonding agent on the approximal surface. CONCLUSIONS: Class II resin composite restorations placed in vivo may be found frequently to show imperfect cervical margins. Overextended margins observed by SEM are difficult to detect on radiographs. When seen on a radiograph, a thick layer of bonding agent may be interpreted as an underfilled restoration.
OBJECTIVES: In this clinical trial, 180 veneer restorations (VRs) were evaluated. The purpose of the study was to collect survival data and to find possible relations between survival and (1) 'type of VR', (2) 'preparation design', (3) 'operator' and (4) the patient-related variables 'tooth-type' and 'vitality of the tooth'. METHODS: The restorations were provided by seven dentists in 1 12 patients on central and lateral maxillary incisors. Experimental variables were: 'type of VR' (either direct resin composite (DC), indirect resin composite (IC) or porcelain (P)), 'preparation design' (with and without incisal overlap) and 'operator'. Failures were recorded at two levels: absolute failure (need for new restoration) and relative failure (need for repair). Survival was defined at three levels: (1) survival of original restoration (Sr, endpoints: 'absolute' failures), (2) functional survival (Sf, endpoints: 'relative' failures) and (3) overall survival (SO, endpoints: both 'absolute-' and 'relative failures'). RESULTS: The variable 'type of VR' showed significant influence on Sf and So but not on Sr. Sf and So rates of P, IC and DC were, respectively: Sf-P, 94%; So-P, 94%; Sf-IC, 94%; So-IC, 90%; Sf-DC, 80%; So-DC, 74%. VRs on vital teeth showed a significantly better survival than VRs on non-vital teeth at all survival levels. CONCLUSIONS: Preparation of the incisal edge for incisal coverage is considered to be unnecessary to assure or improve the strength of VRs. Veneers on non-vital teeth showed higher risk to fail than veneers placed on vital teeth. Porcelain veneers showed the best overall survival.
INTRODUCTION: Problems that may arise in resin composite Class 2 restorations include microleakage and postoperative sensitivity. However, limited in-vivo research is conducted to evaluate these processes. AIM: The aim of this study was to assess postoperative sensitivity, microleakage and the pooling of adhesives in relation to Class 2 box-type composite restorations placed in vivo using various adhesive systems and application techniques. MATERIALS AND METHODS: One hundred and forty-four Class 2 box restorations were placed in the mesial and distal surfaces of 72 premolar teeth in-vivo using one of three combinations of adhesive systems and three filling techniques. After 6 weeks of clinical service postoperative sensitivity was recorded. The teeth were then extracted, immersed in a dye solution and sectioned. Microleakage and pooling of the adhesive was recorded. Statistical analysis involved logistic regression and chi2 tests to identify differences between groups at p < 0.05. RESULTS: Of the 144 restorations, 65 showed minimal cervical leakage in enamel, 5 suffered leakage into dentin and 74 were free of microleakage. No statistically significant differences were found in cervical microleakage between the adhesive systems or between filling procedures. Occlusal microleakage in the enamel was present in 16 of the 160 restorations. Liner Bond 2 restorations leaked significantly more at the occlusal surface (p < 0.05). Pooling of the adhesive was significantly less when PhotoBond was used. No spontaneous postoperative sensitivity was reported. Twenty-eight restorations were sensitive to loading. Postoperative sensitivity was significantly less in patients with Liner Bond 2 restorations. CONCLUSIONS: The adhesive systems used in this study showed minimal leakage into dentin in vivo. Using Liner Bond 2, restorations exhibited more occlusal leakage but were significantly less sensitive to loading.
OBJECTIVE: To investigate the viscosity of two dental adhesives in relation to the adhesive layer thickness. DESIGN: In vitro study. METHODS: The viscosity of several dental adhesives has been determined with a reogoneometer. Both a high and a low viscous adhesive was used to restore class II preparations. These restorations were sectioned and the thickness of the adhesive layer was measured on several defined locations. A statistical analysis was performed. RESULTS: The high viscous adhesive resulted in a thinner layer along the cervical outline of the restoration. With both materials pooling occurred at the line angles of the preparation. On the flat surfaces of the preparations there was a layer of even thickness. CONCLUSION: The differences in thickness of the adhesive layer as often seen on radiographs cannot be explained solely by the use of adhesives with a different viscosity.
OBJECTIVES: The purpose of this study was to compare microleakage, gap formation, thickness of the adhesive layer and its radiographic appearance associated with four adhesive restorative procedures for class I cavities. METHODS: Adhesive systems with easy handling characteristics were selected for the restoration of class I cavities in extracted third molars. Bitewing radiographs were taken of each tooth and four observers were asked to assess the presence of the adhesive layer. Microleakage, gap width and the thickness of the adhesive layer of each restoration were measured upon sectioning of the teeth. RESULTS: Microleakage in the experimental restorations was minimal. The thickness of the adhesive layers and gap formation varied among different adhesive systems. The adhesive system with self-etching primer produced the highest percentage gap-free restorations. Thick adhesive layers could be detected on the radiograph. ROC analysis of the results validates the diagnosis from the radiograph. CONCLUSIONS: The four restorative systems performed well in the prevention of microleakage. The use of a resin modified glass-ionomer cement base did not prevent gap formation compared with the all-etch bonding systems used in this study. The presence of an adhesive layer contributed to the prevention of gap formation, independently of the bonding system used. Thick adhesive layers could be detected on the radiograph.
OBJECTIVES: The aim of this study was to measure the satisfaction of patients with respect to the aesthetics of veneer restorations (VRs) and to identify potential factors influencing their satisfaction. MATERIALS AND METHODS: One hundred and eighty VRs of three different types (direct composite, indirect composite and porcelain) were placed on anterior teeth. Patients were asked to fill in questionnaires at baseline and at one- and two-year recalls. RESULTS: At baseline the overall satisfaction was 76%, after two years this was 78%. The variable 'type of VR' was the only factor measured that had a significant influence on the satisfaction of the patient. At the two-year evaluation patients with porcelain VRs were more satisfied than those with direct composite VRs (P < 0.05). CONCLUSIONS: From the results of this study it is concluded that differences in clinical procedures had no effect on satisfaction. Also the number of VRs had not influenced the level of satisfaction. After two years a significant difference was observed for the variable 'type of VR', with the best results for porcelain.
Three types of veneer restorations (VRs) were evaluated for recognition by two groups of observers to study the aesthetic result. The different types of VRs were: porcelain, direct resin composite and indirect resin composite. One month after insertion of the VRs, colour transparencies were made of smiling patients randomly selected from a group of 112 patients participating in a clinical trial. The slides were evaluated by five dentists who were not familiar with the patients and by 25 beautician students (BS). Dentists were asked to locate the VRs which were present in the patients and to specify the type of VR. BS were only asked to locate the VRs. To trace a possible relationship between the aesthetic result of the treatment and a number of variables, ANOVA was applied to evaluate the variables: 'discolouration of the teeth' before treatment, 'type of VR' and 'number of VRs'. Agreements in judgement were expressed in Cohen-Kappa coefficients. The results showed that the dentists could locate the VRs quite well (Kappa coefficient 0.64 +/- 0.28) but for BS this was lower (Kappa coefficient 0.43 +/- 0.27). The more VRs were made in one patient, the more difficult it was to locate them correctly. The other variables had no significant effect on the recognition of the VRs. It was not possible for the dentist observers to differentiate between the types of VRs.
In this clinical study, 19 full metal crown restorations of canine teeth were placed in seven working dogs. Thirteen canine teeth were severely abraded with no involvement of the pulp cavities; six fractured canine teeth were endodontically treated. At least 1/3 of the coronal part of the canine tooth was available for a supragingivally performed, minimal tooth crown preparation. An adhesive technique to bond the electrolytically etched crown (an alloy of cobalt-chrome-molybdenum) to the tooth was used. The metal crowns, slightly shorter and with a rounder tip than the original tooth, were bounded to the enamel and dentine by using a resin luting cement. Posts or post-and-core techniques were not used. Mean follow-up period was 32 months (range 24-52 months), at which stage 17 crowns were found to be intact and functional. Two crowns were lost as a result of trauma resulting in a fracture of the tooth below the crown.
Amelogenesis imperfecta is a genetic disturbance in the formation of enamel. The condition can be classified as a hypoplastic type and a hypomineralized type. Both types are normally very inconvenient for the patient and treatment should be started as soon as possible. Dental treatment should aim at maintaining the height of the bite and improvement of occlusal function and esthetics. In a few case presentations the possibilities and limitations of adhesive composite restorations in young patients with amelogenesis imperfecta are discussed.
In this article available restoratives for treatment of deciduous teeth are viewed in the light of a theoretical ideal filling material. Especially components and resin composites in combination of a etching primer, approach this ideal in the best way. Clinical studies have to reveal on the long run which material becomes the restorative of choice in the deciduous dentition. For treatment of primary caries in the permanent teeth resin composite offers the best choice.
The operator is a very important factor in achieving high quality posterior composite resin restorations. Specific clinical procedures are required to obtain a clinical successful restoration. Tooth saving preparations are made when primary caries is treated. However, tunnel preparations have major disadvantages. The application of a liner or base under a composite restoration is not required anymore since it does not improve the marginal seal when using an total-etch adhesive. The handling and application of the composite should be done with an injection technique and in layers, whereas low viscous composites are giving the best results in preventing voids.