Clinical performance of porcelain laminate veneers without incisal overlapping: 3-year results.

The aim of this clinical trial was to evaluate the performance of 135 porcelain laminate veneers placed on anterior teeth without incisal preparation. Only 0.3-0.5 mm of the facial enamel was removed using a tapered round-ended diamond bur. The veneers were fabricated from a sintered feldspathic porcelain, etched and silanized and then bonded with a light-cured composite lute. The veneers were yearly examined clinically for debonding, chipping, marginal integrity and staining. After 3 years of service all veneers were retained. Incisal chipping occurred in seven veneered teeth. Wear and staining were negligible. It was concluded that this minimal porcelain veneer restoration with no incisal overlapping was conservative, predictable and successful.

Chemical treatment of cavity walls following manual excavation of carious dentin.

PURPOSE: To improve the conditioning of cavity walls resulting from minimal mechanical preparation of carious lesions, such as is done in modified Class II tunnel preparations. MATERIALS AND METHODS: Proximal carious lesions in premolars and molars were excavated manually and the cavity walls studied using a stereomicroscope and by scanning electron microscopy (SEM) following treatment with either polyacrylic acid, sodium hypochlorite, the enzyme preparation Pronase, or sequential combinations of the agents. Polyacrylic acid (10%) was used according to the manufacturer's instructions, while concentrated sodium hypochlorite (5.25%) was applied with either intermittent scrubbing or with ultrasonic energy for 5-10 minutes, or the cavity wall was incubated with the agent at +/- 37 degrees C for periods up to 24 hours. Incubation with the proteolytic enzyme preparation Pronase was carried out at 37 degrees C for a period up to 48 hours. RESULTS: Manual excavation did not remove all carious dentin, neither did treatment with polyacrylic acid. Scrubbing or sonication with ample amounts of sodium hypochlorite, followed by treatment with polyacrylic acid, or prolonged incubation with sodium hypochlorite, removed most of the remaining carious dentin. However, the "cleanest" surfaces were obtained after 48 hours of incubation with Pronase. Spots of thicker, soft layers of decayed dentin that were left intentionally at some locations could be disintegrated only by the Pronase treatment. It was concluded that treatment with sodium hypochlorite and polyacrylic acid in tandem, or with Pronase may represent potential supplements to conventional cavity cleaning that deserve further investigation. In the clinic more efficient cavity cleaning may improve the bonding ability and thus reduce the risk of marginal ridge fracture in teeth with Class II tunnel restorations.

In vitro shear bond strength of two resin composites to dentin with five different dentin adhesives.

OBJECTIVE: The aim of this in vitro study was to evaluate the shear bond strength to dentin of five different dentin bonding agents in combination with two resin composites (Tetric and Z-100). METHOD AND MATERIALS: Human third molars were selected for the study, and cylindrical posts of either Tetric or Z-100 were bonded vertically to a standard flat dentinal area, prepared on the buccal surface of the teeth. A chisel-shaped shearing blade, attached to the crosshead of a universal testing machine, was positioned so that its edge was immediately adjacent to the adhesive joint. The shear bond strengths to dentin of 10 resin composite-dentin adhesive combinations were measured. RESULTS: The results showed that the bond strength of dentin bonding agents may depend on the choice of restorative material. The in vitro bond strength of dentin bonding agents also differed significantly. In several cases, the bond strength exceeded the cohesive strength of dentin. CONCLUSION: It seems important for clinicians to be acquainted with the variation in bond strength values that is experienced with any bonding system.

Saucer-shaped cavity preparations for posterior approximal resin composite restorations: observations up to 10 years.

OBJECTIVE: This clinical trial aimed at studying the long-term performance in routine clinical practice of saucer-shaped Class II resin composite restorations. METHOD AND MATERIALS: Fifty-one preparations were completed and filled with either of two light-cured posterior composites by seven dentists of the Public Dental Service. The restorations were evaluated annually, using the US Public Health Service criteria, bitewing radiographs, and dies based on replica impressions. At the final evaluation, the recall rate was 100%. RESULTS: After a mean of 7.2 +/- 1.3 years of service (censored maximum of 9.6 years), 70% of the restorations were acceptable for continued use. Caries and technical deficiencies were the main causes of failure. CONCLUSION: The saucer configuration, by respecting and utilizing inherent properties of the resin composites, spares sound dentin and is preferable to the box preparation.

Tunnel restorations placed in routine practice and observed for 24 to 54 months.

OBJECTIVE: The purpose of this study was to evaluate the feasibility and performance of tunnel restorations placed in routine public dental service. METHOD AND MATERIALS: A total of 420 small approximal lesions received tunnel restorations 12 general practitioners. Three hundred two restorations in 179 patients were available for evaluation after a minimum period of 24 months. The restorations were evaluated by modified US Public Health Service criteria. RESULTS: After service periods up to 54 months, 57% of the restorations were found to be clinically and radiographically acceptable. The remainder had already been replaced or were assessed as unacceptable. High levels of carious activity and internal-type preparations resulted in the poorest prognosis. The success rates varied considerably among the operators, but these differences did not reach statistical significance. CONCLUSION: The indications for use of the tunnel restoration technique for the treatment of primary approximal lesions seem to be limited at present. Partial tunnel restorations may have a somewhat better prognosis than the internal tunnels, but high carious activity has a detrimental effect. Tunnel restorations may be considered for particularly cooperative patients with a low caries rate as a semipermanent treatment for small lesions.

Discoloration of dental pellicle by tannic acid.

The ability of tannic acid to discolor pellicle was studied in vitro and in vivo. Freshly extracted teeth were submerget in solutions of tannic acid, and in the clinical study individuals rinsed three times daily with 0.1% or 0.2% tannic acid. It was fount that 0.2% tannic acid caused brownish discolorations within 10-12 days both in vitro and in vivo. Discolored pellicle material collected from the in vivo test group was shown to contain furaldehyde after hydrolysis. The origin of the furaldehyde is not ascertained, but could be due to the presence of dietary deposits, transformation of pellicle pentoses, or from reactions between reducing sugars and amino compounds.

An effect of chlorhexidine and two related drugs on glycosaminoglycans in rat skin.

The aim of the present investigation was to estimate the local effect of three plaque-inhibiting drugs on some glycosaminoglycans in rat skin. The drugs comprised chlorhexidine, dichlorhexidine, and trichlorhexidine; and the glycosaminoglycans examined were hyaluronic acid, chondroitin sulfate, and heparin. Glycosaminoglycans were measured by the carbazole method. Upon subcutaneous injections in rats, chlorhexidine, dichlorhexidine, and trichlorhexidine caused marked reductions in the surrounding skin's content of total hexosamine as well as of the three types of glycosaminoglycans. No significant difference could be demonstrated between the different types of glycosaminoglycans in this respect.

[Light-cured glass ionomer cements]. / Lysherdende glassionomersementer.

An attempt at improving the properties of glass-ionomer cements is represented by the incorporation of light-cure resin systems. This produces materials which have mechanical properties and moisture sensitivity superior to those of present glass-ionomer cements. Such hybrid materials cure by two different mechanisms: polymerization and salt formation. In particular, the early mechanical properties and water sensitivity of the materials are improved due to the formation of a polymer matrix. The tendency to undergo surface crazing during desiccation is also reduced. Three commercially available products are shortly described.

The effect of zinc oxide-eugenol on the shear bond strength of a commonly used bonding system.

It has been claimed that eugenol has a detrimental effect on resin composites and dentin bonding systems. The aim of the present study was to examine whether zinc oxide-eugenol (ZOE) cement would reduce the efficacy of a bonding system. Human third molars were selected for the study, and cylindrical posts of a resin composite (Z100) were bonded vertically to a standardized flat dentinal surface, prepared on the buccal surface of the teeth and treated with Scotchbond Multi-Purpose. The tooth surfaces involved were either freshly cut, or had been exposed to ZOE cement for 6 days, with and without a subsequent thorough cleansing with ethanol. The bond strength in shear was measured after 24 hours. The results showed that ZOE cement had no negative effect on the bond strength of the resin composite (Z100) to dentin when this bonding system was used. The mean shear bond value for the specimens covered with ZOE cement for 6 days was 28.1 MPa. For specimens covered with ZOE cement and cleansed with 96% ethanol, the mean shear bond value was 23.5 MPa. The corresponding value for the controls was 19.0 MPa. These findings suggested that eugenol-containing temporary filling materials may be used safely prior to inserting resin based restorative materials, when Scotchbond Multi-Purpose is employed as the bonding agent.

Possible origin of sulfated glycosaminoglycans in human dental calculus.

The sulfated glycosaminoglycans present in human dental calculus have been shown to be dermatan sulfate and chondroitin-4-sulfate. The composition suggests that the glycosaminoglycans present in calculus, particularly subgingival material, could originate as a result of associated periodontal disease since closely similar compounds have previously been identified in normal and inflamed human gingiva.

The rate of cervical abrasion in dental students.

Abrasion of the cervical region of teeth has been attributed to mechanical cleaning procedures using dentisfrices containing abrasives of various kinds. In the present study the loss of substance during a 26 month period in the cervical region of the upper left premolars of dental students was measured directly by means of a micrometer. The average rate of abrasion was found to be 0.2 micro per day. No difference was observed between the group using a "non-abrasive" dentifrice and that employing a conventional paste. The risk associated with pulp exposure under the conditions observed is briefly discussed.

Furfurals in chlorhexidine-discolored pellicle.

The purpose of the present study was to investigate the possible presence of furfurals in chlorhexidine-discolored pellicle. Pellicle material was scraped off teeth and hydrolyzed in sulfuric acid and the hydrolysate then extracted with ether and examined by thin layer chromatography and gas chromatography-mass spectrometry. The presence of furaldehyde in discolored pellicle was demonstrated by these methods. There were also indications of hydroxymethyl furfuraldehyde in the thin layer chromatograms.

Extrinsic discoloration of teeth.

The majority of tooth discolorations are extrinsic in nature and appear as brown integuments. Various clinical indices and photometric techniques have been used for the evaluation of extrinsic discolorations. Smoking, tea or coffee consumption and increasing age are promoting factors and such discolorations are frequently seen in connection with oral use of antibacterial plaque-inhibiting mouthrinses. Chemical alteration of the acquired pellicle appears to be the major reason for these brown integuments.

Permeability and fluoride release of lining materials containing amine fluorides.

The addition of amine fluorides to a copal recin (Copalite) and a chlorine caoutchouc varnish (Pergut S-40) has been studied. The permeability of Copalite films was only slightly increased whereas the excellent film-forming qualities of Pergut S-40 were destroyed by the addition of fluorides. A high fluoride release was found initially from test films of the materials but within 2-3 weeks a decrease to very low fluoride levels was observed.

The clinical performance of two groups of functioning class-II cast gold inlays.

The length of service and the clinical performance of two groups of functioning class-II cast gold inlays in patients attending a private practice were assessed by conventional clinical and radiographic examination. In one group all inlays were older than 25 years (median age, 34 years), and they had an extended outline form. The impression technique was based on a thermoplastic material in a copper ring. In the other group, comprising inlays inserted during the past 25 years (median age, 16.5 years), the outline form was minimal and an elastic impression material in a copper ring was used. The inlays in the older group appeared to perform better than those in the younger group. In both groups recurrent caries appeared to be the predominant reason for repair.

Saucer-shaped cavity preparation for composite resin restorations in class II carious lesions: three-year results.

This study determined the feasibility of saucer-shaped cavity preparations for composite resins in class II lesions. Saucer-shaped class II cavity preparations were restored with composite resin and subjected to clinical, radiographic, and replica cast evaluation (39 restorations) after 6, 18, and 36 months. The results indicated that the retention, resistance form, and wear resistance of the class II saucer-shaped cavity preparations were satisfactory after 3 years.

Chemical plaque control and extrinsic discoloration of teeth.

Extrinsic discoloration of teeth is an unwanted side-effect in connection with the use of the chemical plaque-preventive agent chlorhexidine. Individual differences in discoloration tendency have, however, been observed. In order to study the nature of these extrinsic discolorations a selection of 3 typical "stainers" and 3 "non-stainers" was made based on the individual tendency to develop extrinsic discolorations of teeth after a ten days rinsing with 0.2% chlorhexidine twice a day. The individual discoloration tendency was maintained through various plaque-preventive regimens. Interference with the retention of chlorhexidine by a cation demonstrated a close correlation between antiplaque activity and the discoloration tendency. A commercial oxidizing agent based on peroxy monosulfate showed the most promising properties in reducing this extrinsic discoloration without interfering with plaque-prevention.

Affinity of hydroxyapatite for furfural and a brown pigment formed by furfural and glycine.

The affinity of hydroxyapatite for furfural and a brown pigment formed by furfural and glycine was studied. A series of mixtures containing 1 M furfural and 0.25-2.0 M glycine were incubated at 37 degrees C and aliquots of hydroxyapatite added. The apatite showed a strong affinity for the brown pigment formed, and an excess of glycine in the mixtures appeared to enhance the binding. The adsorption of furfural to hydroxyapatite was estimated by a spectrophotometric method. The data revealed that pretreatment with CaCl2 and glycine significantly increased the adsorption of furfural.