Adhesive restorations replacing cusps

Contains fulltext : 49219.pdf (publisher's version ) (Open Access)This study addressed a clinical problem in dentistry. The problem concerns the occurrence of complete fracture of a cusp of premolars with an existing Class II restoration, and the required treatment after this cusp fracture. The traditional treatment in these cases is the making of a crown. Crown preparation requires the removal of (sound) tooth tissue. Adhesive restorations, which require less tissue removal, may offer a tissue saving alternative. The general objective was to develop clinical procedures for adhesive cusp-replacing restorations and to investigate their clinical performance. The main questions were: (1) can we rely solely on the adhesion to the remaining tooth surfaces that are exposed after cusp fracture or do we have to alter the cavity configuration and (2) which are the optimal restorative procedures for successful adhesive cusp-replacing restorations? To find answers to the research questions, in vitro load tests, finite element analyses and a clinical study were performed. After fracture of a cusp in a restored premolar and removal of the existing restoration, a large cavity remains that involves the major part of the clinical crown. The point of departure of the treatment in this study was to restore those fractured premolars by a tissue saving technique. This minimal invasive restorative procedure is characterized by the removal of carious tooth tissue and grinding of a bevel; further preparation is omitted. The results suggest that the remaining cavity does not need adaptation. Consequently, the tooth tissue saving approach should be considered in case of cusp fracture in premolars. From the laboratory studies, no essential differences were shown regarding several restoration procedures. Since there are no indications that the clinical behavior of direct and indirect restorative procedures show differences, the preferences of the dentist and the patient dictate the restorative technique of choice.RU Radboud Universiteit Nijmegen, 27 april 2005198 p

Adhesive restorations replacing cusps.

Item does not contain fulltextThis study addressed a clinical problem in dentistry. The problem concerns the occurrence of complete fracture of a cusp of premolars with an existing Class II restoration, and the required treatment after this cusp fracture. The traditional treatment in these cases is the making of a crown. Crown preparation requires the removal of (sound) tooth tissue. Adhesive restorations, which require less tissue removal, may offer a tissue saving alternative. The general objective was to develop clinical procedures for adhesive cusp-replacing restorations and to investigate their clinical performance. The main questions were: (1) can we rely solely on the adhesion to the remaining tooth surfaces that are exposed after cusp fracture or do we have to alter the cavity configuration and (2) which are the optimal restorative procedures for successful adhesive cusp-replacing restorations? To find answers to the research questions, in vitro load tests, finite element analyses and a clinical study were performed. After fracture of a cusp in a restored premolar and removal of the existing restoration, a large cavity remains that involves the major part of the clinical crown. The point of departure of the treatment in this study was to restore those fractured premolars by a tissue saving technique. This minimal invasive restorative procedure is characterized by the removal of carious tooth tissue and grinding of a bevel; further preparation is omitted. The results suggest that the remaining cavity does not need adaptation. Consequently, the tooth tissue saving approach should be considered in case of cusp fracture in premolars. From the laboratory studies, no essential differences were shown regarding several restoration procedures. Since there are no indications that the clinical behavior of direct and indirect restorative procedures show differences, the preferences of the dentist and the patient dictate the restorative technique of choice.RU Radboud Universiteit Nijmegen, 27 april 2005Promotor : Burgersdijk, R.C.W. Co-promotores : Kreulen, C.M., Roeters, F.J.M.198 p

Adhesieve toepassing van zirkonia [Bespreking van: C. Chen (2013) Zirconia-reinforced dental restorations]

In dit promotieonderzoek zijn verschillende eigenschappen en toepassingen van het materiaal onderzocht in een laboratorium. Een aantal uitkomsten is vooral voor de wetenschap en de verdere ontwikkelingen rondom zirkonia interessant, maar er zijn ook enkele belangrijke conclusies te melden voor de algemeen practicus

Diagnostiek en behandeling van gebitsslijtage

Gebitsslijtage wordt veel besproken in tandheelkundig onderzoek en in de media. Het komt steeds vaker voor. Onze zure voeding, veel tandenpoetsen, tandenknarsen en het gebruik van bepaalde medicijnen spelen hierbij een rol. Het is belangrijk om gebitsslijtage al in een vroeg stadium te signaleren, zodat alleen preventieve maatregelen voldoende zijn om ernstiger slijtage te voorkomen. Een goede anamnese om de oorzaak te vinden en een juiste registratie van de ontwikkeling van de slijtage zijn daarbij erg belangrijk. De (preventie)assistent kan een belangrijke schakel in het tandheelkundig team zijn bij de vroegdiagnostiek van gebitsslijtage

[Research methods in dentistry 5. The finite element method]

Contains fulltext : 58892.pdf (publisher's version ) (Open Access)The finite element method is a commonly applied experimental research technique. The method comprises computer simulation of constructions under load and of internal mechanical processes, which enables the study of effects of geometrical and material variations. The analysis shows internal stresses and, consequently, predictions can be made of possible failure. In dentistry, the method is applied in disciplines, such as orthodontics, oral and maxillofacial surgery, implantology en restorative dentistry

The effect of proximal contour on marginal ridge fracture of Class II composite resin restorations.

Contains fulltext : 70756.pdf (publisher's version ) (Closed access)OBJECTIVES: To compare the marginal ridge fracture strength of Class II composite resin restorations placed with a straight or contoured matrix band using composite resins with different modulus of elasticity. METHODS: In 60 artificial first molars standardized MO-preparations were ground. Two matrix systems were used: (1) A straight matrix (Standard Tofflemire Matrix, KerrHawe) in Tofflemire retainer (Produits Dentaire). (2) A contoured matrix (Standard matrix, Palodent, Dentsply). In both groups, a wooden wedge and separation ring (Composi-Tight Gold, GDS) were placed and the matrix was burnished against the adjacent tooth. Three composite resins together were used (Filtek Supreme: e-modulus 13.3 GPa (3M ESPE), Clearfil AP-X: 16.6 GPa (Kuraray) and Clearfil Majesty Posterior: 22.0 GPa (Kuraray)), resulting in six groups (n=10). Teeth were mounted into a MTS servo hydraulic testing machine (Mini Bionix II, MTS, USA) with stylus placed on the marginal ridge. Samples were loaded at a crosshead speed of 1.0mm/min until fracture occurred. Fracture resistance data were statistically analyzed using ANOVA and Scheffe's post hoc test for multiple comparison of groups (p<0.05). RESULTS: Contoured proximal surfaces (365.5+/-87.6N) resulted in significant stronger marginal ridges compared to straight surfaces (290.5+/-64.2N) (p<0.001). Clearfil AP-X (378.1+/-94.63N) provided a higher resistance to fracture than Filtek Supreme (301.4+/-67.3N) (p=0.001) and Clearfil Majesty Posterior (304.5+/-70.6N) (p=0.002). No differences were found between Filtek Supreme and Clearfil Majesty Posterior (p=0.890). CONCLUSION: Within the limitations of this in vitro study it was shown that use of a contoured matrix results in a stronger marginal ridge of a Class II composite resin restoration

Fatigue resistance of teeth restored with cuspal-coverage composite restorations.

Item does not contain fulltextPURPOSE: This study assessed the influence of palatal cuspal coverage on the in vitro fatigue resistance and failure mode of Class II resin composite restorations including replacement of the buccal cusp in premolars. MATERIALS AND METHODS: A master model was made of a maxillary premolar with an MOD amalgam cavity and a simulated fracture of the buccal cusp from the isthmus floor to the CEJ. Using a copy-milling machine, this preparation was copied to 20 extracted human maxillary premolars (group A). Subsequently, the palatal cusp was reduced by 1.5 mm; this modified preparation was copied to 20 additional maxillary premolars (group B). Direct resin composite restorations were made in all teeth. Cyclic load (5 Hz) was applied, starting with a load of 200 N (10,000 cycles), followed by stages of 400, 600, 800, and 1,000 N at a maximum of 50,000 cycles each. Samples were loaded until fracture or to a maximum of 210,000 cycles. RESULTS: Of the restored premolars of group A, 20% withstood all 210,000 loading cycles; in group B, this figure was 55%. In group A, 19% of the fractures ended below the CEJ; in group B, 78% did. CONCLUSION: Palatal cuspal coverage increased the fatigue resistance of Class II resin composite restorations with replacement of the buccal cusp in premolars. However, fractures of restorations with cuspal coverage led to more dramatic failures that made restoration virtually impossible. This suggests caution in lowering remaining cusps for these adhesive restorations in the clinical situation

Comparison of wear between occlusal splint materials and resin composite materials

Tooth wear in bruxing patients often results in a need for treatment with composite restorations. In some cases, bruxing patients receive an occlusal splint as a protective means as well. However, the wear between these opposing materials has not been investigated yet. The aim of this in vitro study was to assess the wear of different splint materials against resin composite materials. A two-body wear test was conducted using the ACTA wear machine. The materials selected for this study were three composites used for direct restorations (Filtek Z250, CLEARFIL AP-X, and Filtek Supreme XT) and four occlusal splints materials, viz. a polyamide resin (ThermoSens) an conventional (hand-processed), milled and printed polymethylmethacrylate (PMMA). As antagonistic materials, stainless steel, Filtek Supreme XT and CLEARFIL AP-X were used. The wear rate of the seven materials was determined after 200 000 cycles, using a profilometry. The rates were analysed using two-way ANOVA and post hoc Tukey's tests. The wear rates were significantly higher for the conventional and milled PMMA materials than for all other materials (P <.001). The wear rates of printed PMMA and the polyamide resin were comparable to composite wear rates. The antagonist materials have minor or no influence on the amount of wear of the various splint materials (P <.001). In conclusion, different splint materials yielded different wear rates for all antagonist materials tested. Keeping in mind that this study is an experimental in vitro study, this finding enables practitioners to choose the splint material necessary according to their patients’ needs