Ceramic laminate veneers: effect of preparation design and ceramic thickness on fracture resistance and marginal quality in vitro.

OBJECTIVES: The aim of the present study was to investigate the influence of five different preparation designs and two different ceramic thicknesses on margin quality and fracture resistance of ceramic laminate veneers after thermomechanical loading in vitro. MATERIALS AND METHODS: Eighty human central incisors were randomly assigned to 10 groups (n = 8) with five different preparation designs: non-prep (NP), minimally invasive (MI) = exclusively enamel-bonded, semi-invasive (SI) = 50% bonded in dentin, invasive (I) = 100% in dentin, and semi-invasive with two additional class III composite resin restorations (SI-C). IPS InLine veneers were fabricated in two thicknesses (L1 = 0.2-0.5 mm; L2 = 0.5-1.2 mm). After adhesive luting (OptiBond FL, Variolink Veneer) with light curing and polishing, specimens were stored in distilled water at 37 °C for 21 days, then thermocycled (2000 cycles between + 5 and + 55 °C), and finally mechanically loaded at the incisal edge at an angle of 45° for 2,000,000 cycles at 50 N und further 1,000,000 cycles at 100 N. Impressions were taken initially, after thermocycling, and after every 250,000 mechanical cycles in order to evaluate cracks and margin quality under a SEM. The veneers were evaluated in a light microscope (× 20) for cracks, chippings, partial, and catastrophic fractures. RESULTS: Margin quality after three million cycles revealed medians for continuous margin of 82-95% without significant differences among groups, neither at the ceramic/composite (p = 0.943) nor at the tooth/composite interface (p = 0.571). Visual inspection of veneers exhibited 22 cracks, 11 chippings, 4 partial and 4 catastrophic fractures in 38 of 80 veneers. The statistical ranking regarding fracture risk (p ≤ 0.05) was: IL1 = SIL1 = MIL1 = IL2 = CL1 = CL2, MIL2 = NPL1 = NPL2 = SIL2, IL2 = CL1 = CL2 = MIL2 = NPL1 = NPL2 = SIL2. CONCLUSIONS: Even after three million cycles with up to 100 N, all groups showed high survival rates. However, the fracture risk increases with thin veneers and preparations with medium to high dentin portions when compared to thicker veneers with preparations in enamel or partially in dentin (p ≤ 0.05). Preexisting resin composite restorations did not show any significant influence on margin quality and facture risk (p > 0.05). CLINICAL RELEVANCE: Ceramic laminate veneers are extremely durable with thin veneers and substantial enamel loss being main risk factors for fracture.

A patient-calibrated individual wax-up as an essential tool for planning and creating a patient-oriented treatment concept for pathological tooth wear.

Tooth wear is generally a physiological process; however, it can also be a pathological condition associated with attrition, abrasion, and erosion processes in which the quantity of tooth loss is atypical for the patient's age. Tooth substance loss often causes functional problems, symptoms of discomfort/pain, and esthetic impairments. Patients presenting this condition frequently need restorative treatment, combined with an increase in the vertical dimension of occlusion (VDO). A diagnostic wax-up (DWU) provides assistance in determining a new occlusal plane and VDO, and is a fundamental tool considering the backward planning involved in the execution of a complex rehabilitation. In cases of severe tooth wear, preventive measures must be taken. Yet, when a restorative intervention is needed, the use of a DWU, in conjunction with a mock-up, helps to achieve a predictable and satisfactory outcome. This article presents a case report of a young female patient with pathological tooth wear, related symptomatology, and esthetic complaints. Initially, a DWU and a diagnostic mock-up were created. After esthetic and functional corrections, a second DWU was generated and transferred to the patient's mouth by means of a therapeutic mock-up. This mock-up was used as a trial restoration for the pretreatment phase, to evaluate the new VDO/esthetics/function and to guide tooth preparation. Lithium disilicate (LS2) occlusal onlays were used to stabilize the VDO, and anterior LS2 and feldspathic veneers, combined with direct composite restorations, were executed to reach the planned minimally invasive result.

Multidisciplinary full-mouth rehabilitation with soft tissue regeneration in the esthetic zone.

OBJECTIVE: Oral rehabilitation often requires a multidisciplinary approach including restorative dentistry, prosthodontics, and periodontology to fulfill high esthetic and functional demands, frequently combined with changes in the vertical dimension. The presence of gingival recessions can be associated with numerous factors, such as brushing or preparation trauma and persistent inflammation of the gingiva due to inadequate marginal fit of restorations. Because gingival recessions can cause major esthetic and functional problems, obtaining stability of the gingival tissue around prosthetic restorations is of essential concern. Modifications of the occlusal vertical dimension require sufficient experience of the whole dental team. Especially in patients with functional problems and craniomandibular dysfunction, a newly defined occlusal position should be adequately tested and possibly adjusted. CLINICAL CONSIDERATIONS: This case report presents a complete prosthetic rehabilitation combined with a periodontal surgical approach for a patient with gingival recessions and functional/esthetic related problems. The vertical dimension was carefully defined through long-term polymethyl methacrylate provisionals as a communication tool between all parts involved. All-ceramic crowns were inserted after periodontal healing as definitive rehabilitation. CONCLUSIONS: Complex rehabilitation in patients with high esthetic demands including soft tissue corrections requires a multidisciplinary team approach that consists of periodontal surgeon, dentist and dental technician.

Combining Esthetic Layering and Lithium Disilicate Sintering Technique on Zirconia Frameworks: A Veneering Option to Prevent Ceramic Chipping.

Major and minor chipping of veneering porcelain are two of the most frequent complications in all-ceramic restorations with zirconia frameworks. In cases of major chipping, replacement of the affected restoration may be necessary. High-strength lithium disilicate ceramic offers new options to serve as veneering material in a sintering technique or as repair material for chipping in combination with the adhesive technique. The purpose of three case presentations here was to describe the use of lithium disilicate ceramic on zirconia frameworks for reliable and esthetic veneering in the posterior region and to repair extended chipping in conventional veneering materials.