Clinical evaluation of the Carisolv chemomechanical caries removal technique according to the site/stage concept, a revised caries classification system.

The objective of the present study was to assess the efficiency and benefit of a chemomechanical system for carious dentin removal, Carisolv, in general practice. A revised caries classification, the site/stage concept, was used to describe the clinical situations of all carious lesions treated. The study was performed by 12 investigators, and 120 carious lesions were treated with Carisolv. Sixty percent of the cases were treated without anaesthesia, and we found a significant correlation between chemomechanical treatment without anaesthesia and absence of pain ( P=0.01). In 78.3% of the cases, carious dentin was totally removed with Carisolv, and in 21.7%, the dentin treatment was completed by drilling. In cases performed with Carisolv alone, the time required to remove carious dentin was 11.1+/-9.51 min (mean+/-SD). Treatment time was equivalent for all sites and increased significantly with each successive stage of lesion progression ( P<0.001). In 82.5% of cases, the clinicians were satisfied with Carisolv, and in 99.2%, so were the patients. We conclude that, using clinical examination methods, Carisolv seems to remove carious dentin at all sites and stages of carious lesions but must be made more efficient for use in general practice.

Dynamic and cyclic fatigue of engine-driven rotary nickel-titanium endodontic instruments.

The absence of adequate testing standards for engine-driven nickel-titanium (NiTi) instruments necessitates further study of these instruments in all areas. This study examined three groups of engine-driven rotary NiTi endodontic instruments (Profile, Hero, and Quantec) and assessed the times for dynamic fracture in relation to the radius of curvature to which the instruments were subjected during preparation, with the instrument diameter determined by size and taper and the mode by which the fracture occurred. Ten instruments were randomly selected representing each size and taper for each group and for each radius of curvature: 600 in total. The instruments were rotated at 350 rpm and introduced into a tempered steel curve that simulated a canal. Two radii of curvature of canals were used: 5 and 10 mm. Time at fracture was noted for all files, and the fracture faces of each file were analyzed with scanning electron microscopy. Radius of curvature was found to be the most significant factor in determining the fatigue resistance of the files. As radius of curvature decreased, fracture time decreased. Taper of files was found to be significant in determining fracture time. As diameter increased, fracture time decreased. In all cases, fracture was found to be of a ductile nature, thus implicating cyclic fatigue as a major cause of failure and necessitating further analyses and setting of standards in this area.

Mechanical properties of nickel-titanium endodontic instruments and the effect of sodium hypochlorite treatment.

The purpose of this study was to assess the mechanical properties--torsional moment, maximum angular deflection, maximum bending moment, and permanent angular deflection--of four brands of nickel-titanium (NiTi) endodontic file, and compare them with a conventional stainless-steel instrument, both in the presence and absence of sodium hypochlorite (NaOCl). NiTi instruments from four manufacturers were randomly selected and subjected to NaOCl treatment for 12 or 48 h, or not at all. The mechanical properties under test were then measured automatically by a digital torque memocouple. Torsional moment and maximum angular deflection indicate the resistance to torsional fracture of an instrument, maximum bending moment the stiffness of the instrument, and permanent angular deflection the strength of the base alloy. All instruments evaluated complied with or exceeded ADA/ANSI Specification No. 28, with the sole exception of the Maillefer ISO size 40 for torsional moment. JS Dental and McSpadden NiTi files were the most resistant to torsional fracture, but all NiTi files were inferior when compared with stainless-steel files from a previous study. However, NiTi files were superior in flexibility, and Maillefer and Brasseler instruments were the best of the instruments tested. NiTi files also had negligible permanent deformation angles. Furthermore, for all properties tested, NaOCl had no statistically significant effect.

Cutting efficiency of nickel-titanium endodontic instruments and the effect of sodium hypochlorite treatment.

The purpose of this study was to assess the cutting efficiency of nickel-titanium (NiTi) files in the presence and absence of sodium hypochlorite (NaOCl) treatment, and compare them to a conventional stainless-steel K-type file. NiTi files from four manufacturers were randomly selected and exposed to NaOCl for 12 or 48 h, or not at all. Their cutting efficiencies were then assessed, using a new methodology: "mass of Plexiglass cut per energy used over 50 linear cutting motions." In the absence of NaOCl, Brasseler (318 micrograms/J) and Maillefer (280 micrograms/J) NiTi files were most efficient, followed by JS Dental (71.4 micrograms/J) and McSpadden (40 micrograms/J). These differences were significant (p < 0.0001), except for those between the latter two brands. Moreover, NaOCl treatment did not alter the cutting efficiency of any brand of instruments significantly. When compared with conventional stainless steel files, all NiTi files tested were less efficient.

Activated adult human alveolar bone cells: a new model of matrix mineralization.

Activated adult human alveolar bone cells were isolated from 2-wk-old osteogenic tissue recuperated from dental implant surgeries following a two-step procedure. Osteogenic tissues were cultured as explant for 2 months. Cells began to migrate in the first 3 d and were confluent in 3-4 wk. However, adjacent to the explants, multicellular cell layers began to form in 10 d, and matrix mineralization was observed by 4 wk in these areas. These formations enlarged and by the end of the culture period, large diffuse matrix mineralization areas were observed. Light and electron microscopic observations confirmed the presence of a collagen matrix undergoing a mineralization process but showing important differences with the mineralized matrix tissue formed with a rat embryo calvaria bone cell system. This new model, using activated human alveolar bone cells, may provide a tool to investigate alveolar bone development and physiology and to set up new therapeutic approaches.

Effects of cleaning, chemical disinfection, and sterilization procedures on the mechanical properties of endodontic instruments.

The aim of this study was to test and compare the values of torsional moment, torsional angular deflection, bending moment, and permanent angular deflection of three designs of root canal files (Unifile, Flexofile, and H-File) before and after cross-infection treatment procedures, according to ANSI/ADA specification no. 28. An increase in value for all mechanical properties tested was observed after the treatment procedures, with the exception of Flexofile wherein a decrease in permanent angular deflection was evident. Unifile showed a decrease in torsional moment and bending moment. The changes in mechanical properties after treatment procedures ranged from 0.1 to 63% from the control groups. Generally, the changes in values observed were insignificant and still well within ANSI/ADA specification no. 28. Thus, they do not have any clinical significance.

Measurement of the cutting efficiency of endodontic instruments: a new concept.

The cutting efficiency of endodontic instruments was measured using an original experimental technique that incorporates new concepts to simulate clinical conditions. Five designs of #ISO 030 endodontic instruments, K-reamer (Maillefer), Flexofile (Maillefer), Helifile (Micro-mega), K-flex (Kerr), and Unifile (De Trey), were chosen and their cutting efficiency assessed at their full working length of 16 mm on two Plexiglas parallelepipeds tilted to follow the 2% conicity of the instruments. For each instrument, four series of 25 cuts were carried out and each cut made on a new flat, smooth Plexiglas surface with an even hardness of 33 VHN. Instruments were tested under a simulated clinical condition of a quarter clockwise turn ROTARY MOTION followed by a PULL ACTION at 16 mm/s rate, with a fixed load on the instrument of 325 g. Water irrigation at a rate of 85 ml/s was supplied before each procedure. Cutting efficiency was evaluated in terms of mass of Plexiglas cut (using a Mettler analytic balance with accuracy of 3 x 10(-5) g) per unit of energy used by the instrument, i.e. mg/J. Unifile was found to have the best cutting efficiency of 0.80 +/- 0.01 (Mean +/- SD) and lowest cutting efficiency loss followed by Flexofile 0.70 +/- 0.03 then Helifile 0.36 +/- 0.01 then K-flex 0.51 +/- 0.07. K-reamer was found to have the lowest cutting efficiency of 0.16 +/- 0.05.

Effects of cleaning, disinfection, and sterilization procedures on the cutting efficiency of endodontic files.

The effects of various cleaning, chemical disinfection, and sterilization procedures on the cutting efficiency of endodontic instruments Unifile (De Trey, Bois Colombes, France), (Flexofile Maillefer, Ballaigues, Switzerland), and H-File (Maillefer)) were investigated. The cross-infection control treatment procedures investigated were as follows: chemical disinfection--NaOCl (2.5%) for 12 and 48 h, and NH4 (5%) for 1 and 4 h; ultrasonic cleaning for 4 and 16 cycles of 15 min; and sterilization methods with chemiclave for 5 and 10 cycles of 20 min, Poupinel for 5 and 10 cycles of 120 min at 180 degrees C and glass beads for 10 and 40 cycles of 40 at 250 degrees C. Cutting efficiency was evaluated as the mass of Plexiglas cut per unit of energy expended by the instrument in microgram/Joule. The cutting efficiency decreased from 1 to 77%, depending on the file design and type of treatment procedures. Heat sterilization (Poupinel) did not modify the cutting efficiency of Unifile and Flexofile. The decrease in cutting efficiency was independent of frequency and duration of treatment procedures.

Chemically separated connective tissue grafts: clinical application and histological evaluation.

Subepithelial palatal connective tissue grafts, separated from the epithelium either chemically (n = 5) or surgically (n = 2) were inserted in patients presenting with gingival recession. Biopsies at the grafted tissue and a portion of non-keratinized mucosa were taken 12 months later. Histology showed keratinization of the newly formed epithelium, and interestingly a deep projection of epithelium into the connective tissue in almost all biopsies, sometimes with an enlargement and a cyst-like space. We conclude that chemical separation of epithelium and connective tissue is clinically feasible for connective tissue grafts and that the subepithelial connective tissue grafting technique should be modified to avoid this projection of epithelium.

Clinical effectiveness of subgingival irrigation with a pulsated jet irrigator versus syringe.

Previous studies have shown clinical and microbiological improvement with subgingival irrigation particularly after scaling and root planing. In this study we monitored the effects of saline irrigation on non-treated periodontal pockets. Ten subjects with severe periodontal disease and symmetrical lesions on multirooted teeth were selected. They had not received periodontal treatment or antibiotics for the previous 6 months. Patients were given simplified oral hygiene instructions. Neither scaling nor root planing was provided during the study. Two teeth were randomly selected per quadrant for subgingival irrigation with saline solution. One side was treated with a syringe and the other side with a pulsated jet irrigator with a modified tip, professionally administered. Clinical parameters (pocket depth, plaque index, gingival index, crevicular fluid, bleeding index, attachment level, and subgingival microflora) were evaluated on days 0, 15, 30, 60, and 90. Both subgingival irrigation products induced changes (reductions) in these indices during the study. Significant differences (P less than 0.001) with the oral irrigator were found for the following parameters: microscopy, pocket depth, crevicular fluid, and plaque index. In this study, professionally administered saline irrigation with a pulsated jet irrigator was more effective than syringe treatment with the same solution. Neither treatment resulted in a detectable gain in probing attachment level. Since gain in attachment level is achievable by other techniques, neither of these subgingival irrigation procedures alone can be considered adequate for periodontal therapy.

[Biological glues and biomaterials in periodontal surgery. Description of a surgical reattachment technic]. / De l'interet des colles biologiques et des biomateriaux en chirurgie parodontale. Description d'une technique chirurgicale régénératrice.

A major research problem over the past 10 years is to obtain a new attachment after treatment of roots previously exposed to periodontal disease. Among the most recent studies, two main objectives of surgery are suggested: a selection of cell population and to arrest epithelial migration by guided tissue regeneration with a membrane, and a biological and chemical root preparation with citric acid and fibronectin. A technique for the treatment of deep osseous lesion is put forward here: the association of biodegradable membrane--natural coral--citric acid and fibronectin.

[Endosteal stimulation in implantology. Study and results after 2 years]. / La stimulation endostée en implantologie. Etude et résultats après 2 ans.

Analysis of implant failure in the maxilla has showed that these failures were predominant on bone that had remained toothless for a period exceeding 2 years. Histological and osseostructural studies demonstrate that the loss of maxillary teeth has an essential effect on its vascularisation, more than on the bone loss; this vascularisation is absolutely necessary in order to obtain an adequate and lasting osseointegration. When, after surgical preparation of the receiver bony site, no bleeding is noted, insertion of the implant is postponed. Six weeks later, the new socket is curetted and the scar tissue removed; this showed that, systematically, the vascularisation was markedly increased. Results at 2 years of this "endostal stimulation", applied to Brånemark and I.M.Z. implants, are: 95.5% success in the maxilla, compared to 83% with osseointegration during the same period. This technique may be applied in the posterior mandibular area, when there is a marked resorption and the short implant is only inserted in cortical bone, minimally vascularized, because of the presence of the mandibular canal; the results of this latter technique are actually poor.