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At least 181 records · Page 10Linked to original sources
PubMed1991

Reduction of cervical gaps in class II composite resin restorations.

Class II cavities prepared in brass models and in extracted teeth were restored with three light-cured composite resins. A transparent cone-shaped device (Light-tip) at the end of the light source was pressed into the filling material in the proximal box for curing the resin. A second layer was filled in the recess left by the cone and cured without the cone. Controls consisted of fillings cured in two layers. In the brass cavities the contraction gap was 10 microns (+/- 10.6) with use of the cone compared with 109.5 microns (+/- 46.5) in control fillings (p less than 0.001). Extracted teeth were restored without etching of the enamel. Cervical contraction gaps in control restorations were reduced by more than half with the use of the transparent cone technique.

Acrylic Resins↗
PubMed1991

Modification of the resistance form of amalgam coronal-radicular restorations.

Three groups of 10 extracted endodontically treated mandibular molars were mounted in acrylic resin. The occlusal surface was reduced until a 4 mm pulp chamber height remained. A peripheral shelf 2 mm deep and 1.4 mm wide was placed on one group, while four TMS Minim pins were placed 45 degrees to the long axis of the tooth into the facial and lingual walls of the second group. The final group served as the control and had no further treatment. All teeth were then restored with amalgam. An Instron testing machine was used to apply a controlled force to the beveled amalgam at a crosshead speed of 2 mm/min until fracture occurred. A peripheral shelf did not improve the fracture resistance of the coronal-radicular restorations tested. The specimens with semihorizontal pins were significantly stronger than specimens from the other groups. Placement of pins into the pulp chamber is recommended when adequate dentin remains.

Analysis of Variance↗
PubMed1991

Microhardness of Class II composite resin restorations with different matrices and light positions.

The degree of polymerization, determined by surface hardness, has been related to the gingival marginal adaptation of posterior composite resin restorations. Poor marginal adaptation results from marginal leakage and failure of the restoration. This study compared the degree of polymerization, measured by microhardness, of a microfilled composite resin placed by use of different matrices. The effect on polymerization with the curing light in two positions was also evaluated.

Composite Resins↗
PubMed1992

A simplified matrix for making direct cores.

This article describes the use of a pharmaceutical gelatin capsule as a matrix for making various posted and nonposted crown substructures. The procedure used for a cast post and core using this matrix is outlined.

Capsules↗
PubMed1992

Microleakage of composite resin and glass ionomer cement restorations in retentive and nonretentive cervical cavity preparations.

Ketac Fil glass ionomer cement (GIC) and Scotchbond 2 dentinal bonding agent (DBA)/Silux Plus composite resin restorations were inserted in cervical cavity preparations of extracted human teeth. After thermocycling, the specimens were invested and sectioned longitudinally and horizontally through the center of the restoration. Microleakage was evaluated as a ratio of the extent of methylene blue dye penetration at the tooth-restoration interface. Although all restorations exhibited leakage, both the GIC and bonded composite resin restorations recorded less leakage in retentive than in nonretentive cavity preparations. Composite resin restorations in nonretentive cavity preparations showed significantly more dye penetration toward the pulpal chamber than the GIC restorations. Ketac Fil GIC restorations inserted without a matrix strip exhibited less leakage than those with a matrix strip. The most desirable results were recorded with Scotchbond 2 DBA/Silux Plus composite resin restorations in retentive preparations.

Acid Etching, Dental↗
PubMed1993

Amalgam restorations: a new approach.

A conservative approach to amalgam restorations is presented for using a chemomechanical method for softening and removing decay and using a dental adhesive resin for bonding amalgam to tooth structure, reducing the need for mechanical retention and preserving sound tooth structure.

Acid Etching, Dental↗
PubMed1994

Assessment of gingival margin thickness before margin placement.

Matrix material can be cut and placed beneath the gingival tissue to mimic a metal collar on a metal/ceramic crown restoration. If this metal matrix causes a discoloration of the gingival tissue, it would be wise to restore the tooth by using an all-porcelain margin.

Crowns↗
PubMed1991

A serum substitute promotes osteoblast-like phenotypic expression in cultured cells from chick calvariae.

The effects of medium supplements were tested on embryonic chick calvarial cells in culture. Isolates were divided among four treatment groups: Nu-Serum, chicken serum, fetal bovine serum, or calf serum. Expression of the osteoblastic phenotype was assessed by cell morphology, DNA content, [3H]thymidine incorporation, lactate production, cellular and medium alkaline phosphatase activities, and collagen synthesis. Cells grown in Nu-Serum demonstrated increased alkaline phosphatase activity and a six-fold higher rate of collagen synthesis compared to chicken serum. These cells displayed a polygonal profile, abundant rough endoplasmic reticulum, Golgi apparati, and elaborated an extensive matrix of banded collagen which was well mineralized by day 10 of culture. Although highly mitogenic, chicken serum promoted a more fibroblastoid morphology. Compared to the sera tested, Nu-Serum preferentially promoted the osteoblast-like phenotype in chick calvarial cells in culture.

Alkaline Phosphatase↗
PubMed2005

A randomized clinical trial on proximal contacts of posterior composites.

OBJECTIVE: The objective of this study was to investigate clinical changes in proximal contact strength inserting Class II composite resin restorations according to one of three randomly assigned protocols. MATERIALS AND METHODS: Seventy-one Class II restorations (MO/DO) were placed by two calibrated operators. Restorations were randomly assigned to one of three groups: one using a circumferential and two a sectional matrix system with separation rings. Proximal contacts were measured by one independent observer with a Tooth Pressure Meter immediately before treatment, and directly after finishing the restoration. RESULTS: Compared to the situation before treatment groups with a sectional matrix system resulted in a statistical significant stronger mean proximal contact strengths (p<0.05), whereas the use of a circumferential matrix system with hand-instrument resulted in a lower proximal contact strength (p<0.05). CONCLUSION: Class II posterior composite resin restorations placed with a combination of sectional matrices and separation rings resulted in a stronger proximal contact than when a circumferential matrix system was used.

Acrylic Resins↗
PubMed2006

The long-term effect of a composite resin restoration on proximal contact tightness.

OBJECTIVE: The aim of this study was to investigate changes in proximal contact tightness up to 6 months after the restorative treatment. MATERIALS AND METHODS: In a randomised clinical trial Class II composite resin restorations were placed in 52 patients. Proximal contact tightness was measured before, directly after, and 6 months after treatment. These data were analysed statistically using linear regression and t-tests. RESULTS: Proximal contacts, that increased in tightness as result of the treatment tend to loose tightness after a 6-months period but remain tighter than before treatment. Proximal contacts, that decreased after treatment hardly change after 6 months. CONCLUSIONS: A change in contact tightness after restorative treatment will not always remain stable over time.

Adult↗
PubMed2006

Class II composite restorations with metallic and translucent matrices: 2-year follow-up findings.

OBJECTIVE: The aim of this randomized, clinical study was to evaluate the performance of composite restorations placed with two matrix and wedge systems after a 2-year follow-up. METHODS: Twenty-three patients were selected, and received at least two Class II restorations, one with metallic matrix and wooden wedge and other with polyester matrix and reflective wedge. One dentist placed all the 109 restorations. All cavities were restored using Single Bond and P-60 (3M ESPE), according to manufacturer's instructions. In the metal matrix group, polymerization was performed from occlusal, and in the polyester group, through the reflective wedge. Restorations were evaluated at baseline and after 12 and 24 months by the modified USPHS criteria, and data were analyzed with Mann-Whitney and Wilcoxon Signed Rank tests (alpha=0.05). RESULTS: Fifteen subjects and 78 restorations were re-evaluated after 24 months. A significant decrease in the quality of cervical adaptation and proximal contacts by radiographic evaluation was evidenced (p<0.05), but no differences between the two matrix systems were detected (p>0.05). In the clinical evaluation there were no significant differences between matrices after 2 years (p>0.05). A compromising of marginal adaptation, marginal staining and proximal contacts aspects for both matrix systems was evidenced, and restorations placed with translucent matrices showed loss of color stability (p<0.05). CONCLUSIONS: Whereas restorations presented some clinical aspects somewhat compromised after 2 years, the matrix and wedge systems evaluated showed similar clinical performance.

Adolescent↗