The management of soft tissue defects using the "gingival shaving" technique

A simple, effective technique is described for the correction of unfavourable gingival contour during post-surgical or pre-prosthetic procedures. Termed the "gingival shaving technique", it is conducted with high-speed course diamond burs. Results are relatively rapid and predictable, especially in cases where esthetics are most desirable. The technique can be performed by the periodontist or prosthodontist, and can be repeated until satisfactory gingival contour is achieved. Case selection, careful preparation, and post treatment management and care are essential for success.

Effects of high-speed cutting on dentin permeability and bonding

The effects of high-speed cutting by use of a diamond bur with or without water coolant or sanding by 80-grit SiC paper on dentin permeability, before and after surface treatment, and dentin bonding of adhesive resins were compared. Three different bonding systems were used: Scotchbond DC, which requires no removal of smear layers, and two others, Clearfil Photobond and Superbond C&B, both of which remove smear layers (phosphoric acid gel or 10% citric acid containing 3% ferric chloride, respectively). Creation of smear layers by bur cutting or sanding reduced dentin permeability to levels that were only 1-3% of the maximum permeability values. Scotchbond DC gave low but consistent bond strengths (3.7-6.1 MPa) to dentin covered with smear layers. Clearfil PHotobond also produced consistent bond strengths (8.6-9.4 MPa). The increase in the permeability of dentin after phosphoric acid treatment was higher when the SiC paper was used (146%) than when the high-speed bur was used (87-90%). The smear layer and smear plugs produced by the diamond bur were more resistant to 10-3 treatment than were the SiC-created smear layers. The bond strengths of Superbond showed the highest bond strengths to the conditioned dentin when the high-speed cutting was used with water coolant (16.3 MPa), compared with the other two groups (12.2-12.5 MPa).

Tooth preparation for full-coverage restorations using the enamel milling technique

There are many acceptable methods of tooth preparation for full-coverage restorations. The technique used should be systematic, with step-by-step procedures to produce an easily followed routine. This will minimize undesirable, haphazard tooth reduction. The technique presented in this paper is a simple, exacting, and conservative method of tooth reduction, requiring a minimum of instrumentation.

Interproximal reduction in the molar/premolar region: the new approach

Interproximal reduction in molar and premolar region is discussed and the questions of the amount of enamel that can be removed, the effect of fluoride on the altered tooth surface, the periodontal considerations and the effect on pulp tissue of cutting enamel are addressed. Moreover a fine diamond bur suitable for air-rotor stripping of posterior interproximal enamel is also described.

Temperature changes during the finishing of amalgam restorations

The finishing and polishing of amalgam restorations may be harmful to the pulp because of the heat generated during these procedures. In this study, changes in temperature of the pulp in extracted teeth were determined in vitro. During the polishing procedure, a variety of instruments were used under a variety of circumstances: with or without a water coolant, intermittent or continuous operation, high or low rotation speed, and high or low pressure. Finishing or polishing without a water coolant always increased the temperature of the pulp. When the pressure was high, during continuous polishing, or during a higher velocity of rotation, pulpal temperatures increased more than 20 degrees C within 30 seconds. However, when a water coolant was used, a decrease in the temperature was always observed. Procedures carried out with low pressure showed a decrease in the pulpal temperature of approximately 9 degrees C. High pressure decreased the temperature of the pulp by only 4 degrees C. Therefore a water coolant is always advised when amalgam restorations are being finished and polished.

Comparisons of different debonding techniques for ceramic brackets: an in vitro study. Part I. Background and methods

Techniques for removing metal orthodontic attachments are, for the most part, not as effective with ceramic brackets because the properties of ceramic brackets differ greatly from those of the conventional metal orthodontic brackets. Currently available ceramic brackets are composed of aluminum oxide crystals in either a polycrystalline or monocrystalline form that has a low fracture toughness compared with that of stainless steel. Metal brackets will deform 20% under stress before fracturing, whereas ceramic brackets will deform less than 1% before failing. The purpose of this study was (1) to evaluate the debonding characteristics of three different types of ceramic brackets when removed by techniques recommended by the manufacturers; (2) to evaluate and compare the conventional, ultrasonic, and electrothermal bracket-removal techniques, and (3) to evaluate and compare the mean enamel loss from removal by high-speed bur, by slow-speed bur, and by the ultrasonic method. In the first phase of the investigation, 140 teeth (70 maxillary central incisors and 70 third molars) were bonded with one of three types of ceramic brackets. Three different debonding methods were tested--(1) the conventional method recommended by the manufacturer (either pliers or wrench), (2) an ultrasonic method that employed specially designed tips, and (3) an electrothermal method involving an apparatus that transmits heat to the bracket. In each of the test groups, five variables were evaluated during and after bracket removal: (1) the incidence of bracket failure, (2) the amount of adhesive remaining after bracket removal, (3) the site of bond failure, (4) the debonding time for each technique, and (5) enamel damage resulting from bracket removal.(ABSTRACT TRUNCATED AT 250 WORDS)

[Study on method for examining bone quality for dental implant. Relationship between cutting force and bone mineral content]

A number of factors, including, for example, patient jawbone condition, influence prognosis of dental implants. At present, X-ray and intraosseous punctures are employed as means of examining bone quality. But lack of definite criteria makes objective evaluation difficult. In order to develop a more reliable method for making objective evaluations of bone quality for dental implant, this study quantitatively measured the cutting force at an intraosseous puncture and investigated its relation to bone mineral content, a parameter of bone condition. Methods One side of each of 4 mandibles obtained from adult Japanese cadavers was fixed with formalin. The mandibles were free of deformity and injury to the jaw or face but lacked molars (these materials were the property of the Department of Anatomy, the Tokyo Dental College). Drilling tests were made in 5 samples taken from each of the 4 mandibles (20 in all), and bone mineral content was measured. Prior to the drilling test, the dental engine was remodeled to produce an experimental test machine permitting quantitative measurement of the cutting force (cutting torque) exerted on cutting instrument in the direction of rotation. The device was fitted to a universal testing machine and constant-feed-speed drilling tests were performed. Cutting force on the cutting instrument produced during drilling was divided into cutting torque (cm-g) in the direction of rotation and cutting load (gf) in the direction of feeding. Densitometry and image analysis were used to measure bone mineral content. X-ray photograph were taken from each sample with an aluminum reference, the density of which was digitalized and measured. The density value was then image analyzed, and bone mineral content of the drilled site was obtained as relative value calculated in aluminum equivalent (mmAl). Comparative examinations of cutting torque, cutting load, and bone mineral content were made through the same drilled site at every 1.0 mm-depth from surface. Results and Conclusions 1. The experimental test machine permitted quantitative measurements of the cutting force exerted on the cutting instrument in the direction of rotation (cutting torque). 2. Quantitative measurements on the cutting force during drilling produced the following values: cutting torque--0.4 to 56.5 cm-g with an average of 8.7 cm-g; cutting load--1.7 to 1419.7 gf with an average of 169.3 gf. 3. Bone mineral content at the drilled site ranged from 0 to 0.67 mmAl and averaged 0.19 mmAl.(ABSTRACT TRUNCATED AT 400 WORDS)

[Crystalline glass ceramics model teeth]

The feeling of hardness, stickiness and the rate of cutting during the preparation of a tooth were compared using an extracted tooth, melamine resin and crystalline glass ceramics model tooth (Bioram M) which are used in dental education and practice. Diamond burs were used with an air-turbine handpiece in this experiment. The results indicated that Bioram M had the desirable characteristics of a model tooth and there was a strong resemblance feeling of cutting between Bioram M and a natural vital tooth.

[Smear layer on prepared dentin]

Whenever dental tissues cut with a rotary instrument, a layer of grinding debris and organic film left of their surfaces, which is described by the term "smear layer". In this paper, we present the morphology and views for the formation of the smear layer. Additionally, we examine the influence of smear layer, on dentin permeability, infection by bacteria beneath dental restorations and on bonding capacity of adhesive dental materials. Following, detailed description of cleaning and chemical agents, used for smear layer removal from prepared dentin surfaces.