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An ideal tooth-gingiva relationship is important to aesthetics and function. Predictable methods of establishing an ideal tooth-gingiva relationship are described for exposing and aligning impacted teeth.
The major causes of post-transplantation tooth loss following tooth replacement after avulsion (exarticulation) and surgical replacement of impacted maxillary canines (auto-transplantation) are inflammatory root resorption and replacement resorption (ankylosis). This paper attempts to outline the treatment and management of replanted teeth using the current philosophies of splinting, endodontic therapy and the use of calcium hydroxide in the re-attachment of the periodontal ligament (PDL). Clinical research during the past 20 years has provided sufficient information for the development and establishment of a rational and effective program of treatment.
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.
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.
A mathematical representation of tooth morphology may help to improve and automate restorative computer-aided design processes, virtual dental education, and parametric morphology. However, to date, no quantitative formulation has been identified for the description of dental features. The aim of this study was to establish and to validate a mathematical process for describing the morphology of first lower molars. Stone replicas of 170 caries-free first lower molars from young patients were measured three-dimensionally with a resolution of about 100,000 points. First, the average tooth was computed, which captures the common features of the molar's surface quantitatively. For this, the crucial step was to establish a dense point-to-point correspondence between all teeth. The algorithm did not involve any prior knowledge about teeth. In a second step, principal component analysis was carried out. Repeated for 3 different reference teeth, the procedure yielded average teeth that were nearly independent of the reference (less than +/- 40 microm). Additionally, the results indicate that only a few principal components determine a high percentage of the three-dimensional shape variability of first lower molars (e.g. the first five principal components describe 52% of the total variance, the first 10 principal components 72% and the first 20 principal components 83%). With the novel approach presented in this paper, surfaces of teeth can be described efficiently in terms of only a few parameters. This mathematical representation is called the 'biogeneric tooth'.
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.
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.
The present investigation evaluated the effect of 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) on alveolar bone formation during tooth movement in rats. Orthodontic elastics were inserted between the maxillary first and second molars on bilateral sides in male rats. 1,25(OH)2D3 was injected locally, at the concentration of 10(-10) M, once every 3 days in the submucosal palatal area of the root bifurcation of the molar on the right side. Histomorphometric analysis revealed that tooth movement without application of 1,25(OH)2D3 decreased the mineral appositional rate (MAR) on the compression area at 7 days. Repeated injections of 1,25(OH)2D3 in the orthodontically treated animals distinctly stimulated alveolar bone formation on the mesial side at 14 days. There was a significant increase in MAR associated with elevated osteoblast surface (Ob.S/BS) value on the tension surface. These findings suggest that local application of 1,25(OH)2D3 enhances the reestablishment of supporting tissue, especially alveolar bone of teeth, after orthodontic treatment.
The results of this preliminary evaluation of a tooth implant model combining a stylized tooth root design and a thin, highly biocompatible microporous carbon coating, although tentative, add support to the feasibility of developing a statisfactory system for the immediate replacement of selected teeth in healthy bone.
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.
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.
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.
We have determined the localization of Cav1.2 (L-Type) Ca2+ channels in the cells and nerve fibers in molars of normal or injured rats. We observed high levels of immunostaining of L-type Ca2+ channels in odontoblast cell bodies and their processes, in fibroblast cell bodies and in Schwann cells. Many Cav1.2-containing unmyelinated and myelinated axons were also present in root nerves and proximal branches in coronal pulp, but were usually missing from nerve fibers in dentin. Labeling in the larger fibers was present along the axonal membrane, localized in axonal vesicles, and in nodal regions. After focal tooth injury, there is a marked loss of Cav1.2 channels in injured teeth. Immunostaining of Cav1.2 channels was lost selectively in nerve fibers and local cells of the tooth pulp within 10 min of the lesion, without loss of other Cav channel or pulpal labels. By 60 min, Cav1.2 channels in odontoblasts were detected again but at levels below controls, whereas fibroblasts were labeled well above control levels, similar to upregulation of Cav1.2 channels in astrocytes after injury. By 3 days after the injury, Cav1.2 channels were again detected in nerve fibers and immunostaining of fibroblasts and odontoblasts had returned to control levels. These findings provide new insight into the localization of Cav1.2 channels in dental pulp and sensory fibers, and demonstrate unexpected plasticity of channel distribution in response to nerve injury.
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.
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.
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.
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.
The interaction of powdered human tooth enamel and dentin with NPG-GMA was studied in alcoholic and alcoholic-aqueous solutions. The reaction produces ionized carboxylic groups capable of forming ionic bonds between the calcium ions in the tooth enamel or dentin and NPG-GMA.