A clinical evaluation of Class II composites placed using a decoupling technique.

PURPOSE: This study was undertaken to evaluate the three-year clinical performance of Class II restorations of a fine particle hybrid composite placed using a decoupling placement technique, whereby polymerization shrinkage stresses at the cervical tooth-restoration interface were minimized by separating the initial gingival increment of composite from the body of the restoration using a polyurethane varnish. MATERIALS AND METHODS: The study was a practice-based explanatory, single-center clinical trial. A minimum of 40 Class II restorations of the material under investigation (Tetric) was required to be placed in predominantly molar teeth in selected patients. The restorations were placed using a decoupling incremental technique, bonding being accomplished using Syntac and Heliobond. The restorations were reviewed within 1 month of placement, thereafter at 18 months, then at 2 and 3 to 4 years using predetermined codes and criteria. Impressions and photographic records were used to obtain retrospective, third-party assessments of the restorations. RESULTS: Of 43 restorations originally placed and found to have ideal characteristics at baseline review, 41 (95%) were reviewed at 18 months, 36 (84%) at two years, and 31 (74%) at 3 to 4 years. None of the restorations were found to have suffered significant deterioration, notwithstanding three restorations having been lost to the study because of the replacement of part of the restored tooth for causes other than the catastrophic failure of the material. No secondary caries or postoperative sensitivity was recorded. CONCLUSION: It was concluded that the findings support the use of the material under investigation in the restoration of moderate- to large-sized Class II preparations in selected patients. The decoupling placement technique employed may be found to be an effective means to limit postoperative sensitivity and to contribute to the favorable in-service performance of restorations of the type investigated. Good practice would now require a multicentered, randomized controlled trial to investigate the effectiveness of the material and, in particular, the decoupling technique under the conditions of everyday practice.

Flowable resin composites as "filled adhesives": literature review and clinical recommendations.

There is increasing reliance on laboratory testing of new products. The clinical significance of many such studies can be questioned. To function clinically, bond strength must develop more quickly than the shrinkage stress. Oxygen inhibition of extremely thin resin layers prohibits establishment of the bond, perhaps particularly relevant for single-component dentin bonding agents. Use of thicker layers of radiolucent hydrophilic bonding materials can lead to difficulties during subsequent radiographic diagnosis and may contribute to degradation at enamel margins. Shrinkage stress is influenced significantly by many factors. The cavity geometry probably plays the most important role but cannot be controlled to any major extent by the operator. Shrinkage and modulus kinetics are also critical, involving variables such as content and type of monomers, the catalyst system, and the light intensity. In general, a high modulus of elasticity or more rapid polymerization leads to increased shrinkage stress. Combining a single-component adhesive as a dentin primer with a highly radiopaque flowable resin composite as a filled adhesive may help overcome these difficulties.

Restoration of a single anterior crown.

All-ceramic restorations have gained patient acceptance and are increasingly being used in aesthetic appearance-related restorations. This case report of a single anterior crown matching natural dentition utilizes some of the new special-effect ceramic powders designed for use with the layering technique. These powders help to properly replicate incisal, mamelon, and gingival areas. The clinical procedure is described, using photographs of the case to illustrate the steps involved.

The strength of a heat-pressed all-ceramic restorative material.

A heat-pressed technique (IPS Empress, Ivoclar) has been described to construct single unit crowns, inlay/onlays and veneers using precerammed and precoloured glass-ceramic ingots. The aim of the study was to evaluate the strength of materials obtained using this technique. Strengths were determined by means of shell (disc rupture) tests. Seven groups of 10 specimens each were prepared with different combinations of core, incisal and glaze firing. Shell strength values of these seven groups varied between 167 +/- 18 and 81 +/- 9 MPa. After analysis, results showed that there was no statistical difference between groups when the core porcelain was in tension. However, there was a significant difference between those groups in which the lower surface was either core or incisal porcelain. The component thicknesses of the core and incisal materials did not change the strength of the complete specimen.

Direct pulp capping with a dentinal adhesive resin system: a pilot study.

The clinical and histological responses of exposed pulpal tissue after direct capping appear to be more closely related to bacterial infiltration than to direct material toxicity. Dentinal bonding agents have been suggested as a replacement for calcium hydroxide for pulpal protection. In this pilot study, direct pulp capping with a glutaraldehyde-containing dentinal adhesive was performed on eight permanent premolars and molars. The teeth were immediately restored with a resin composite restoration. The clinical technique included the use of a calcium hydroxide paste to cover the exposure site during completion of the preparation. Enamel and dentin were etched with phosphoric acid. All teeth remained vital and without symptoms during the initial observation period of 2 to 6 months.

Influence of light intensity on two restorative systems.

OBJECTIVES: High intensity curing lights are recommended almost universally on the basis of immediate curing depth measurements. Although this single factor is well documented, the influence of light intensity on other parameters has not been investigated extensively. METHODS: Two restorative systems were examined with two light intensities in regard to four properties; polymerization shrinkage (density method), flexural modulus and strength (ISO 4049), hardness profiles after post-cure (Vickers), and marginal adaptation in dentine cavities (quantitative margin analysis). RESULTS: The variation in light intensity did not significantly affect curing contraction or post-cure hardness profiles to a depth of 4.5 mm for either resin composite. Significant differences were found in flexural modulus with both restoratives; only one material demonstrated a light intensity-related influence on flexural strength. Marginal gap formation increased in each bonding agent/resin composite pair with increased light intensity. CONCLUSION: In clinically relevant layer thicknesses, curing a resin composite with a higher intensity light may demonstrate significant disadvantages due to increased shrinkage stress.

IPS Empress. Restoration of a single anterior crown.

All-ceramic restorations have gained patient acceptance and are increasingly being used in aesthetic appearance-related restorations. This case report of a single anterior crown matching natural dentition utilizes some of the new special-effect ceramic powders designed for use with the layering technique. These powders help to properly replicate incisal, mamelon, and gingival areas. The clinical procedure is described, using photographs of the case to illustrate the steps involved.