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At least 469 records · Page 26Linked to original sources
PubMed1976

[Hemisection, tooth separation and root amputation].

It is possible to utilize a segment of multirooted tooth as a healthy abutment even though retention of the entire tooth is impossible due to advanced periodontal disease, carious lesion or endocontic failure. The criteria for success of tooth hemisection, root separation or root amputation is dependent on the following factors: -proper case selection based upon adequate diagnostic tests -periodontal condition (amount of supporting bone) surrounding the remaining segment -condition of the remaining dentition -the ability to establish optimal occlusal relationship with minimal traumatic forces -the ability to perform satisfactory endodontic procedures, using an aseptic technique -stabilization by means of fixed prosthesis -the ability to establish an environment amenable to optimal oral hygiene.

Crowns↗
PubMed1978

Root formation in ectopically transplanted teeth of the frog rana pipiens. II. Comparative aspects of the root tissues.

In the second part of an experimental study of the behavior and fate of the roots of ectopically transplanted frog teeth the comparative aspects of the tooth root and its tissue composition were examined. Experimental results showed that the root or pedicel area of the frog tooth was an intrinsic part of the tooth. The tooth was capable of growth to normal size and shape with or without the presence of underlying bone. When compared with existing descriptive exidence and analysis it was determined that the best terminology for the amphibian root tissues would be dentin right up to the point of attachment where cellular basal bone is seen. This is because it is an intrinsic part of the tooth, if formed on the pulpal side of the root sheath, and is formed by odontoblasts. Because of the above observations, the original Hertwig's epithelial root sheath appeared both homologous and analogous with the mammalian sheath, but since all the root tissues were under this sheath, no tissues homologous to any of the paradental tissues of cementum, periodontal ligament, or alveolar bone could be found except when the root sheath injury resulted in induction of an acellular tissue upon the outer surface of dentin.

Animals↗
PubMed1993

Temperature and surface changes of dentine and cementum induced by CO2 laser exposure.

The thermal effects of a CO2 laser on the external root surface and inside the root canal were studied in vitro by means of computerized infrared (IR) thermography and a digital thermometer. One-hundred-and-eighty tooth roots with single root canals were irradiated internally and externally with laser power set at 0.5, 1, 1.5, 2, 3 and 4 W. The laser was used in two operating modes: pulsed (pulse 0.5 s) and continuous mode with exposure time of 10 s. Under the conditions of this experiment, temperature rises of between 1.5 and 19.1 degrees C at the external root surface and 1.5 and 12 degrees C inside the root canal and horizontally across the sectioned root surface were recorded. The results obtained with IR camera showed a higher temperature on the external root surface than the digital thermometer during and after lasing the root canal. Scanning electron microscope (SEM) analysis revealed that even low laser energy significantly damaged the external root cementum surfaces.

Body Temperature↗
PubMed2004

Apical problems--coronal solutions: how changes in access cavity design can prevent and overcome problems with curved canals.

There is no doubt that the preparation of curved canals presents one of the greatest challenges in endodontic and is fraught with potential difficulties. Canal curvature can only be seen on a radiograph in the mesio-distal plane and yet it is well known that curvature in the bucco-lingual plane is also evident in many teeth. A primary cause of failure of endodontic treatment is the persistence of microbial infection. In curved canals this is often due to procedural errors such as ledges, fractured instruments and canal blockage. Over the years a variety of techniques have been proposed for preparing these canals. Whether it is the straightforward endodontic treatment of a straight, single rooted tooth, or retreatment of a curved molar with a number of procedural errors, the access cavity has a crucial role in the achievement of successful endodontic treatment. The size and shape of the access cavity will be dictated by the degree of curvature of the canals and the objectives that have to be achieved.

Dental Instruments↗
PubMed1998

Decoloration of 1% methylene blue solution in contact with dental filling materials.

OBJECTIVES: Leakage studies have been performed frequently, since a tight seal provided by various dental fillings has been considered clinically important. The dye penetration experiment using a methylene blue solution as a tracer is one of the most common methods applied in these types of studies. The stability of the colour of methylene blue in contact with six dental filling materials was observed. METHODS: Silicon rubber tubes and human tooth roots of 10 mm in length and 1.5 mm inner diameter were filled with amalgam, calcium hydroxide, Cavit, Fuji II, mineral trioxide aggregate, or zinc oxide eugenol, 10 tubes or roots for each material. Groups of five tubes or roots filled with the same material were immersed in 0.8 ml 1% methylene blue dye solution. The optical density of the methylene blue solution before immersion and after 24, 48 and 72 h of immersion was measured in a spectrophotometer at 596 nm. RESULTS: The methylene blue solution was found to be decoloured over time by all the test materials (P < 0.01) except for Fuji II, in both silicone tubes and roots. At 24 h, the optical density value of methylene blue decreased by 73% for the Ca(OH)2/silicone group and 84% for the mineral trioxide aggregate/silicone group. CONCLUSION: Methylene blue is decoloured by some dental filling materials, which may result in unreliable results for these materials in dye leakage studies.

Aluminum Compounds↗
PubMed2002

Cementum: a phosphate-sensitive tissue.

Ectopic calcification within joints has been reported in humans and rodents exhibiting mutations in genes that regulate the level of extracellular pyrophosphate, e.g., ank and PC-1; however, periodontal effects of these mutations have not previously been examined. These initial studies using ank and PC-1 mutant mice were done to see if such mineral deposition and resulting ankylosis were occurring in the periodontium as well. Surprisingly, results indicated the absence of ankylosis; however, a marked increase in cementum formation on the root surfaces of fully developed teeth of these mutant mice was noted. Examination of ank mutant mice at earlier ages of tooth root formation indicated that this striking observation is apparent from the onset of cementogenesis. These findings suggest that cells within the periodontal region are highly responsive to changes in phosphate metabolism. This information may prove valuable in attempts to design successful therapies for regenerating periodontal tissues.

Animals↗
PubMed2006

Symmetry of non-carious cervical lesions in canines and premolars.

OBJECTIVES: Clinically non-carious cervical lesions (NCCLs) are frequently seen. The aim of this study was to investigate the relationship between the shape and symmetry of NCCLs, wear of cuSPS and triangular ridge, and the curvature of the tooth root. METHODS: One hundred and twenty-nine extracted human upper canine teeth and 274 extracted human upper premolar teeth with NCCLs were used in this study. The specimens were studied using photographs and three-dimensional scanning. RESULTS: Asymmetric NCCL was observed in 69.0% of the canines and 44.5% of the premolars. Wear of cusp and lingual ridges was observed in 82.9% and 93.0% of the canines, respectively. Wear of the buccal cusp and buccal triangular ridge was observed in 85.4% and 89.8% of the premolars, respectively. On the other hand, the wear of lingual cusp and lingual triangular ridge was observed in 89.1% and 93.8% of the premolars, respectively. The curvature of the root was observed in 48.1% of the canines and 43.4% of the premolars. CONCLUSIONS: There was no relationship between the symmetry of NCCLs, and the wear of cuSPS and triangular ridges for either canines or premolars. Although there was a relationship (p < 0.05) between the symmetry of NCCL and the curvature of the root in the canines, no relationship was observed between the symmetry of NCCL and the curvature of the root in the premolars.

Bicuspid↗
PubMed2004

Management of a non-vital central incisor tooth with three root canals.

A macrodont permanent central incisor tooth with unusual root canal morphology became non-vital 18 months following trauma. Two root canals were initially identified and filled, but the patient continued to have symptoms and radiographic examination indicated apical periodontitis. Careful radiographic and clinical examination revealed a third root canal, which was subsequently treated, resulting in the resolution of symptoms and periapical healing.

Child↗
PubMed1999

Treatment of lower second premolar agenesis by autotransplantation: four-year evaluation of eighty patients.

The frequency of agenesis of the second lower premolar is 2.5-4%. In growing patients, early extraction of the deciduous molar and subsequent closure of the space is a common therapy, but in some cases space closure is deemed unlikely and autotransplantation is an alternative. The aim of the study was to analyze the outcome of autotransplantation in replacing missing lower second premolars and to evaluate the associated presurgical orthodontic treatment. The material consisted of records of all patients with teeth transplanted to the lower second premolar region during the period 1988-89 at the Department of Oral Surgery, Eastman Institute, Stockholm. The following variables were registered: sex, age, number of transplanted teeth, donor tooth, root development, recipient site, orthodontic treatment, persisting temporary molar, total number of congenitally missing teeth, the surgeon responsible, and clinical and radiological follow-up variables. Of 110 transplanted teeth, 99 had not completed root formation, and in 11 teeth the root formation was completed. The success rates after 4 years were 92% and 82%, respectively. Both premolars and molars served as donor teeth, but the main donor tooth was the upper second premolar. Fourteen percent had been orthodontically treated only because of the transplantation, i.e. to open the space for the donor tooth. Treatment of agenesis of the second lower premolar by autotransplantation has a good prognosis. In growing individuals the transplant not only maintains growth and development of the alveolar ridge but also provides a permanent solution to the agenesis.

Adolescent↗
PubMed1975

On optimum orthodontic force theory as applied to canine retraction.

The study reported here was undertaken in an attempt to contribute, from a theoretical standpoint, to the knowledge and understanding of optimum force theory, particularly as it may be relevant to canine retraction. The following statements are derived from my analysis of the applicable published literature and the results of the present investigation: 1. This study lends support to the beliefs, from the findings of previous investigations, 20, 22 that the center of rotation for simple tipping is three tenths to four tenths of the distance from the root apex to the alveolar crest and that the center of resistance is at approximately midroot for the single-rooted tooth. 2. For a given distal driving force, increasing the countertipping couple from zero causes the center of rotation to "move" from a point near the apical end of the middle third of the root to the root apex and then to infinity. That is, the couple to be developed by the appliance to produce crown movement is smaller than required for bodily movement. Also, increasing the rotational stiffness of a canine-retraction appliance will result in greater inherent potential for canine root control and a greater probability of achieving bodily movement. 3. In a specific orthodontic case, an average periodontal stress value (active force divided by root area) can be used as a basis of comparison of suggested active force magnitudes among several single-rooted teeth having different root surface areas, provided all teeth are to experience the same form of displacement (for example, bodily movement). Similarly, differences in average stress magnitudes developed in the periodontium, rather than differences in root surface areas, are actually the basis for the differential force theory. 4. Clinical studies have suggested that the size of active force for bodily movement or root movement of a given tooth be two to three times that employed in simple tipping of the same tooth. Induced stress levels in the periodontium, especially at the root apex and alveolar crest locations, can be related to suggested magnitudes of aplied crown force components.

Activator Appliances↗
PubMed2002

Prevalence of short-root anomaly in healthy young adults.

Short-root anomaly (SRA), occurring mostly in maxillary incisors, is defined as developmentally very short, blunt dental roots. The condition has a genetic background and is related to hypodontia. Earlier population studies have been based on schoolchildren with developing dentitions and have indicated prevalence figures between 1% and 10%. We studied a random sample of existing panoramic radiographs of 2000 university students for SRA. Roots as long as or shorter than the crowns in the incisors and visually evaluated as very short, blunt roots bilaterally in the posterior teeth were classified as SRA. The prevalence was 1.3%. According to anamnestic information, half the SRA patients had undergone orthodontic therapy, but pre-treatment radiographs were unavailable. In 70% of the SRA patients the short-rooted tooth pairs were upper incisors, but also involved were maxillary premolars, lateral incisors, and lower second premolars. Women were significantly more often affected. We discuss other factors known to cause short-rooted teeth and conclude that the population prevalence for genetic SRA in fully developed dentitions is close to our 1.3%.

Adult↗
PubMed1980

[Distribution characteristics of the root apices of multirooted teeth in the mandible].

Changes in the mandibular height and thickness of its alveolar part have been studied, with special reference to the relation existing between the apices of the molar teeth roots and the external and internal surfaces of the mandible and the mandibular canal. The investigation was carried out in 148 male and female sculls having the lower jaw, in 115 maxillodental cuts. It has been stated that the greatest mandibular height is in males at the level of the first premolar teeth (23.4+/-0.82 mm) and the smallest -- at the level of the second molar (32.01+/-0.52 mm). The thickness of the alveolar part at the level of the root apices of the first premolar is the smallest both in males and females (9.578+/-0.301 mm -- 11.068+/-0.69 mm); the greatest -- at the level of the third molar (13.0+/-0.632 mm -- 15.5+/-0.55 mm). The distance between the root apex and the external surface of the alveolar part is the least at the level of the first premolar, at an average 3.12 mm. The mandibular osseous structure and the relation of the tooth root with the mandibular canal are clearly seen in electroroentgenograms.

Adult↗
PubMed1992

A method for histological examination of undecalcified teeth.

A method is presented for histological examination of undecalcified ground sections of tooth roots affected with periodontal disease. The roots were placed in Karnovsky's fixative overnight, postfixed in 2% buffered osmic acid, and dehydrated in an ascending series of ethanol. The specimens were then infiltrated with propylene-oxide and Epon-Araldite resin, embedded in Epon-Araldite, and sections were prepared using a cutting and grinding system. The resulting ground sections were 8-12 microns thick. The sections were allowed to air dry at room temperature. When thoroughly dried, a coverglass was applied using resinous mounting medium DPX. The specimens were examined by phase-contrast microscopy. The method is useful for simultaneous examination of mineralized dental tissue and bacterial morphotypes covering the root surface of teeth involved with periodontal disease.

Histological Techniques↗
PubMed1987

Supragingival root surface removal during maintenance procedures utilizing an air-powder abrasive system or hand scaling. An in vitro study.

The purpose of this study was to determine the amount of root surface removal in vitro using an air-powder abrasive system or sharp curet on root surfaces simulating the cumulative effects of an every 3-month periodontal maintenance regimen over a 3-year period and to compare the amount of time spent in the utilization of each instrument. Fifty extracted teeth with fully formed roots were cleaned and mounted in one of 10 different artificial alveolar arches. Each arch contained one central incisor, one lateral incisor, one canine, one first and one second premolar. The buccal and mesial tooth root diameters were measured initially and after each treatment with a digital point micrometer. All teeth were stained with coffee and repositioned in their artificial alveolae and treated by the air-powder abrasive system or curet until all visible stain was removed. Time required for removal of stain in both treatment groups was recorded. Both groups were restained, retreated, and retimed 12 times to reproduce a 3-month maintenance interval for 3 years. The average root structure removed by the air-powder abrasive system following each treatment was 10.68 micron while the curet removed an average of 27.09 micron. Stain was removed 3.15 times faster by the air-powder abrasive system than with a curet.

Air↗
PubMed1996

Treatment of root fracture by CO2 and Nd:YAG lasers: an in vitro study.

The purpose of this in vitro study was to use scanning electron microscopy and polarized light microscopy to evaluate the feasibility of using either the CO2 laser or an Nd:YAG laser in combination with air/water surface cooling to effect fusion of fractured tooth roots. The experimental unit consisted of 81 single-rooted teeth, each with an induced root fracture. Fifty-six teeth that had been reapproximated in dental stone and 25 teeth that had been reapproximated with C-clamps were assigned to untreated control groups or groups for treatment using CO2 and Nd:YAG lasers. Laser treatment consisted of multiple passes along the line of fracture, which was inspected using a dissecting microscope after each pass until a visual indication of fusion or irreparable damage resulted. Scanning electron microscopy evaluation of the treated lines revealed heat-induced fissures and cracks, areas of cementum meltdown and resolidification, crater formation, and separation of cementum from underlying dentin. In no instance-regardless of reapproximation technique, laser type, energy, and other parameters-did the treatment effect fusion of the fractured root halves.

Argon↗
PubMed1996

Resumed tooth development following avulsion of a permanent central incisor.

A case is presented in which an upper right central incisor was avulsed because of trauma at age six. At the time of trauma it was suspected that the pulp had remained in the socket although the tooth had been lost. No attempt was made to treat the socket, remove the pulp, or replant the tooth. Follow-up radiography showed that, despite initial apparent complete loss of the calcified portion of the tooth, root development proceeded to completion.

Child↗
PubMed1997

Dentoalveolar morphology: evaluation of natural root form versus cylindrical implant fixtures.

The function of implant-supported restorations is now routinely achieved. As a result, the emphasis in restorative implant dentistry has shifted from function to aesthetics and the biocompatibility of the materials utilized. The learning objective of this article is to review the three major components essential to achieving natural aesthetics in implant-supported restorations--hard tissue dynamics, soft tissue dynamics, and dental aesthetics. Particular emphasis is directed to the dentoalveolar anatomy and morphology. Analysis of the tooth root morphology and dimensions has resulted in the design and fabrication of restorative components with dimensions that closely resemble the natural tooth anatomy and aesthetics. A system of transmucosal abutments has been designed, and its utilization is presented in this review.

Alveolar Bone Loss↗