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Time required to remove totally bonded tooth-colored posterior restorations and related tooth substance loss.

OBJECTIVES: The study was conducted to measure the time required to remove large totally bonded tooth-colored posterior restorations and related tooth substance loss. This information was collected to determine if there were differences between bonded restorations and conventional restorations. METHODS: Molars were restored with the following materials: amalgam, composite, glass ionomer cement or glass ceramic cusp coverages. After submitting them to an in vitro aging process, they were attached to a lower jaw model in a phantom head. Six dentists removed the test restorations under standardized, quasi-clinical conditions. RESULTS: While the amalgam was completely removed, some glass ionomer cement vestiges were found. In the glass-ceramic group, the margins were covered with remnants of the composite luting agent in several places. The most restorative material was left in the composite group. The loss of tooth structure after removal of amalgam, glass ionomer cement, composite and glass ceramic was 17.6 mm3, 19.6 mm3, 39.9 mm3 and 41.8 mm3, respectively. When comparing the removal time, the glass ionomer group scored best with an average of 11.9 min followed by the amalgam group with an average of 15.2 min, followed by 24.9 min for the composite group and 30.4 min for the glass ceramic group. SIGNIFICANCE: The removal of totally bonded posterior restorations made of composite and ceramic is more technically demanding and more time-consuming than the removal of glass ionomer and amalgam restorations.

Acrylic Resins

A 3-year follow-up of a homotransplanted tooth from a tooth bank.

A successful case of homologous tooth transplantation is presented. A maxillary second premolar obtained from a tooth bank was implanted into a fresh central incisor extraction site. A 3-yr follow-up radiograph indicated satisfactory apical healing and minimal replacement resorption. Clinically, the transplantation site was free of symptoms and there was no evidence of periodontal disease or tooth mobility.

Adult

[Adhesion of dental resin to tooth structure--syntheses and adhesion to tooth structure of various aliphatic methacrylates with a carboxylic group].

Twelve aliphatic methacrylates with a carboxylic group [succinate (2 MES, 5 MPeS and 10 MDS), methylsuccinate (2 MEMS, 5 MPeMS and 10 MDMS), maleate (2 MEM, 5 MPeM and 10 MDM) and citraconate (2 MEC, 5 MPeC and 10 MDC)] were synthesized by the addition of four dicarboxylic acid anhydrides to each of three different alkylene chain length hydroxy methacrylates to investigate the relationship between the methacrylate structure and its bonding to tooth. The bond strength of methacrylates to polished tooth surface decreased with increasing alkylene chain lengths under dry conditions, but water immersion reduced this change. The bond strength of succinate and maleate to polished tooth surface was higher than that of methylsuccinate and citraconate under dry conditions. All methacrylates showed high bond strength to etched enamel, with maleate showing the highest bond strength. On the other hand, the bond strength of 2 MEM and 5 MPeM to etched dentin was markedly high, and about 5 microns thick resin reinforced dentin at the interface between etched dentin and resin (2 MEM or 5 MPeM) was observed by SEM and EPMA analysis.

Adhesiveness

Examination of tooth-drying techniques: evaluation in-vitro of a prototype warm-air tooth dryer.

A prototype, rechargeable, warm-air tooth dryer is evaluated and its capabilities compared with those of an established mains electricity powered dryer (Handi-Dri). The evaluation includes warm-up cycle, maximum temperature and constancy of temperature of air output, battery discharge profile, time required to dry etched enamel, ability to dry wet filter paper, flow rate and pressure of air output, convenience and ease of use. Selected tests were also applied to a dental 3-in-1 syringe. Alternative methods of drying the tooth surface are also reviewed. The prototype was found to be suitable for tooth drying; it was considered safer and more convenient than the Handi-Dri and offered advantages over other methods.

Air Pressure

[Osteoplastic tooth transposition. Surgical method for orthognathic placement of a single tooth].

The procedure described in this article is based on the surgical subtotal luxation of a tooth-containing alveolar segment and allows the repositioning of single teeth while almost regularly safeguarding tooth vitality. This procedure has proven particularly effective in the treatment of maxillary anteriors, canines and premolars. For patients preferring surgical correction to long-term orthodontic treatment this limited operative intervention allows safe orthodontic alignment. To date, relapses have not been observed in the cases treated. Stable immobilization of up to six weeks postoperatively is achieved by splinting.

Alveolar Process

Trends in tooth loss due to caries and periodontal disease by tooth type.

Although the patterns of dental disease is gradually changing, caries and periodontal disease still account for the most important reason for extractions in most countries. However their relative contributions towards overall tooth mortality figures varies. The aim of this study is to investigate the types of teeth usually associated with extractions due to caries or periodontal disease and its relation to the age at which the tooth was lost. The highest proportion of extractions due to caries occurred between 21 to 30 years of age while that for periodontal disease occurred between 41 to 50 years. For caries, the greatest proportion of extractions involved the posterior teeth. The most frequently extracted teeth due to caries are the molars, in particular the first permanent molar. However, for periodontal disease a slightly greater proportion of anterior teeth were lost than the posteriors. This trend is more marked in the lower jaw than the upper. Overall, extractions related to caries tend to increase posteriorly, while that for periodontal disease tend to increase anteriorly.

Adolescent

[Tooth root length and tooth neck diameter as indicators in sex determination of human teeth].

The length of the dental root and the diameter of the tooth neck are odontometric parameters which to date have rarely been used for the differentiation of the sexes. Teeth of 166 individuals from the early medieval burial ground of Eichstetten (south Germany) were available for examination. A correlation analysis was performed to show the possible dimensional interrelation of teeth which, however, applies only to the dental neck parameters. Using only diameters of the tooth neck and length of dental roots, it was possible to perform a new sex determination for 68 of the 166 individuals. It shows a good coincidence with a traditional sex determination. A traditional sex determination, performed in advance, as well as the archeological assignment of typical sex related grave goods were used for verification. For future sex determination based on teeth, examinations are recommended to be restricted to the six-year molar, the first upper premolar and, in particular, the canine. Also the dental neck diameter proved to be more useful than the crown diameter. Dental root lengths can be neglected. By comparing the results with those of a second Alamannic burial ground it could be established that discriminant analyses performed within the same population are highly congruent.

Female

Electric currents, bone remodeling, and orthodontic tooth movement. II. Increase in rate of tooth movement and periodontal cyclic nucleotide levels by combined force and electric current.

Piezoelectric currents in mechanically stressed bone were implicated in the activation of bone cells. The objectives of this experiment were to determine the usefulness of exogenous electric currents in accelerating orthodontic tooth movement and to study the effect of electric-orthodontic treatment on periodontal cyclic nucleotides. Maxillary canines were tipped in five cats by 80 g force. Two groups of five cats each were treated by an electric-orthodontic procedure to one maxillary canine for 7 and 14 days, respectively. Teeth treated by force and electricity moved significantly faster than those treated by force alone. Enhanced bone resorption was observed near the anode (PDL compression site), while bone formation was pronounced near the cathode (PDL tension site). Staining for cyclic nucleotides was increased when electric stimulation was added to the mechanical force. These results suggest that orthodontic tooth movement may be accelerated by the use of locally applied electric currents.

Alveolar Process

Tooth wear, solubility and fluoride concentration of molar-tooth surfaces in rats maintained on simultaneous or separate intake of food and fluoridated drinking water.

Eighty rats, 20 days old, were fed a hard pellet diet and deionized or fluoridated (25 parts/10(6) F-) drinking water respectively for 40 days. Half were maintained on simultaneous food and water intake for 3 h, daily, and the remainder on separate intake of food for 3 h followed by drinking water for 3 h, daily. Scanning electron micrographs of the occlusal surface of right maxillary first molars were used for scoring wear. The mandibular and left maxillary molar surfaces were used for solubility and fluoride concentration determinations. Intake of food and water separately did not affect wear significantly, whereas solubility and fluoride concentration of the molar surfaces were significantly increased. Wear, solubility and fluoride of the molar surfaces respectively were highly significantly increased in the rats provided with fluoridated water. Increase in fluoride uptake is due in part at least to the increase in sites available for uptake due to tooth wear. Acid dissolution of worn tooth-surface enamel is greater than that of intact enamel.

Animals

Maternal smoking and tooth formation in the foetus. I. Tooth crown size in the deciduous dentition.

Altogether 2159 pregnancies among black and white Americans in the Collaborative Perinatal Study and dental casts from the children at the age of 5-12 years were studied to find out the effect of maternal smoking on deciduous tooth crown growth. Minor crown size reduction (2-3%) in some dimensions was found in children whose mothers had smoked during pregnancy. The possible change in dimensions seems to be influenced by sex, race and smoking habit. The critical time periods of the gestational development (16th to 19th) weeks would possibly appear from these data to be targeted by the detrimental effect of maternal smoking. It is concluded that deciduous tooth sizes seem to be greatly unaffected when compared to reduction in birthweight.

Black People

An analysis of tooth position on initial tooth contact.

A closed circuit television movement detector was used to study mandibular movement in the form of tooth tapping, in subjects with no apparent dental disease or malocclusion. The velocity and form of various phases of movement was studied, in the transverse, sagittal and coronal planes, from measurements made on u.v. charts and X-Y recordings. It was shown that closing movements were more direct and faster than opening movements; that initial contact on closing is in a well-defined contact area, followed by a sliding of cusps over each other to a final centric position and that the closing path of the mandible in tapping movements is in the form of a smooth curve showing simple axis rotation through distances normally greater than those accepted clinically. It was also shown that microphone signals can be detected at times other than when normally expected, indicating displacement with tooth contact, at times other than at the fully intercuspated position.

Dental Occlusion, Centric

[Variations of pathological tooth loss with special reference to tooth erosion--apropos of a case].

Importance of tooth surface loss has increased in dental practice. It is difficult to determine aetiological factors and the exact diagnosis, because the symptoms are often combined. The aim of the present study was to summarise the most important factors of tooth surface loss, mainly of erosion which is a frequent form. Reviewing the literature aetiological factors, symptoms, differential diagnostic problems and therapeutic advice are discussed. Prevention, early diagnosis and treatment are very important in these patients.

Adult

Tooth loss and tooth retention in a multitribal group of Bantu-speaking South African blacks: a study on 500 dry mandibles.

Tooth loss and tooth retention in adult South African Bantu-speaking Negroes were studied from data derived from 500 dry mandibles. The tribe, sex, and stated age of the specimens were available. Mandibles were equally distributed over the third to seventh decade of life. The presence of dental units was recorded and analysed within and between decade age groups. The mandibles carried a total of 5,459 dental units. Between the third and fourth decades of life and between the sixth and seventh decades, the reduction of the frequency of dental units was mild and statistically not significant. It was, however, severe and significant between the fourth and fifth, and the fifth and sixth decades. In the third-decade group, most teeth were found in the anterior region with a tendency to diminish in number posteriorly. After the third decade there was a definite persistence of first premolars and canines with significant tendency toward loss of teeth anterior and posterior to them. Only the incisors and third molars showed significant reduction in number from the third to the fourth decade. The reduction of all teeth was statistically significant later, until the sixth decade of life. Although there was loss of teeth from the sixth to the seventh decade, it was not significant for any of the homologous dental units. There is a possibility that some dietary differences existed between the older subjects (50-70 years old) and the younger ones (20-49 years old) which may have had some influence on the results.

Adult

Tooth and tooth surface survival rates in birth cohorts from 1965, 1970, 1975, and 1980 in Lahti, Finland.

Differences in the tooth and tooth surface survival rates between four cohorts born in 1965, 1970, 1975, and 1980 were analysed in a historical cohort study including data on the permanent teeth of children aged 5-7 years at baseline and 19 years at the end of the study. A statistically significant reduction in caries occurrence in fissured surfaces in the three oldest cohorts was seen during the 3 years after the eruption of the teeth. Caries occurrence in the cohorts born in 1975 and 1980 did not differ from each other. The occurrence of caries in smooth surfaces was low in all age cohorts. Therefore, despite a systematic decrease in caries occurrence towards the younger cohorts, no significant differences were found between the cohorts in smooth surface decay. After the 3 first posteruptive years, practically no differences in survival rates between the cohorts were observed. In the two youngest cohorts, the figures during the 3 first years after eruption did not differ from the figures for the later years. Throughout the study, caries occurrence was symmetric and no gender differences were observed. No postponement of decay was found by the end of the follow-up time.

Adolescent

[Adhesion of restorative resin to tooth substance. Treatment of tooth surface with aqueous solution of amino-acid derivatives and HEMA].

Although many studies have been made on the reinforcement of the bond between tooth and restorative resin, satisfactory results have not been obtained clinically. Attempts were made to obtain such a reinforced bonding using the aqueous solution of derivatives of amino acid, either N-methacryloyl alanine (MAL) or N-acryloyl alanine (AAL), and 2-hydroxyethyl methacrylate (HEMA). Following the treatment with these surfactants, a tensile bond strength of 103 kgf/cm2 (to enamel) and 80 kgf/cm2 (to dentin) was obtained by MAL-HEMA solution, and that of 99 kgf/cm2 (to enamel) and 58 kgf/cm2 (to dentin) in the case of AAL-HEMA solution. This is considered as the result of either the etching effect of the amino acid derivatives, effect of its reactive products with hydroxyapaptite or reaction between HEMA and an organic component of tooth structure, like a collagen.

Acid Etching, Dental