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At least 451 records · Page 25Linked to original sources

PubMed2003

Patterns of vertical root fracture: factors affecting stress distribution in the root canal.

Previous studies have indicated that vertical root fracture tends to occur in a buccolingual direction, where dentin thickness is greatest. Factors potentially influencing the location and direction of root fracture include root canal shape, external root morphology, and dentin thickness. In this finite-element study, simulated root sections were varied systematically with respect to canal size and shape, external root morphology, and dentin thickness to determine their relative contribution to vertical root fracture. Similar models were constructed based on cross-sections of human tooth roots that had been fractured clinically or experimentally. Finite-element models demonstrated that canal curvature seems more important than external root morphology, in terms of stress concentration, and that reduced dentin thickness increases the magnitude but not the direction of maximum tensile stress. Models based on actual root fractures showed a strong similarity between tensile-stress distribution and fracture patterns.

Computer Simulation↗

PubMed2000

Heat transfer to the periodontal ligament during root obturation procedures using an in vitro model.

It appears to be important to avoid thermal injury to the periodontal ligament when using heated guttapercha techniques such as "System B." An in vitro model was developed, consisting of an extracted human tooth rooted in an artificial periodontal ligament (PDL) and alveolar socket, which allowed us to measure the temperature transferred to the root surface. The teeth were instrumented and subsequently embedded in alginate to simulate the PDL. Medium gutta-percha points were fit, sealer was applied, and a fine Buchanan plugger was used for condensation. Temperature measurements were taken simultaneously at the apex and 5 mm from the apex during obturation with two fine gauge thermocouples connected to a digital thermometer. The average temperature increase was approximately 1 degree C at the apex and approximately 2 degrees C at the 5 mm mark. The resulting temperature increases appear to be lower than previously reported by other investigators (Hardie, 1986, 1987; Barkhordar et al., 1990; Weller et al., 1991; Lee et al., 1998), who did not allow for the heat disseminating effect of the PDL.

Alginates↗

PubMed1991

Disarming canine teeth of nonhuman primates using the submucosal vital root retention technique.

Removing or reducing the size of canine teeth of baboons and macaques has become an accepted practice to minimize the potential for injury to laboratory animal care personnel. A submucosal vital root retention procedure was adapted from the technique of root banking human teeth. In this technique, the crown of a tooth is amputated below the level of the alveolar bone crest, and the exposed pulp covered by a mucoperiosteal gingival flap. Our aim was to disarm the canine teeth of baboons and macaques with a single surgical procedure that would preserve a vital tooth root buried in alveolar bone under normal mucosa. Our long-term objective was to develop a technique that would not require further clinical management during the life of the animal. This paper presents the surgical techniques used.

Animals↗

PubMed2006

Root resorption in relation to orthodontic tooth movement.

Root resorption is an undesirable sequela of orthodontic tooth movement. The odontoclasts are responsible for root resorption and the process of hyalinization is known to preceed the orthodontic root resorption. It is found that there are several predisposing factors, therefore an evaluation of these factors should be done by careful examination of personal medical history, severity of malocclusion and dental treatment (if any due to previous history of trauma), anterior crossbite etc. The evaluation becomes an essential factor as it helps the orthodontists in detecting the occurance and severity of the root resorption and thereby plan out the treatment more effectively. Orthodontic tooth movements especially intrusion and other movements like tipping, torque are all known to influence the root resorption, therefore the detection using radiographs and repair of root resorption is of utmost significance as root resorption is a more serious problem from a medicolegal stand point of view. However some studies have shown that the repair process is known to occur after the cessation of orthodontic treatment by the deposition of cementum of cellular type. In the light of orthodontist's liability of what is basically an unpredictable phenomenon, it is necessary that the speciality define this uncertainity and protect its members against unnecessary and unjustified litigation.

Humans↗

PubMed1978

Histologic response of replanted teeth pretreated with acidulated sodium fluoride.

Central incisors in the vervet monkey were extracted, endodontically treated, and replanted into their original sockets after immersion in a 2 per cent acidulated sodium fluoride solution (pH 5.5) for 30 minutes. Histologic examination at 1, 2, 4, and 8 weeks postoperatively showed that by the second week resorption had taken place and that ankylosis, first seen by the fourth week, along both the buccal and palatal root surfaces, was well established by the eighth week. Under the conditions of the study, pretreatment of the tooth roots with 2 per cent acidulated sodium fluoride did not reduce root resorption and ankylosis.

Acids↗

PubMedDate not supplied

[Etiologic factors which affect the development of infrabony periodontal defects].

The aim of the study was to examine frequency and distribution of etiologic factors which, associated with chronic inflammation, can influence the forming of intrabony periodontal defects. The following were studied: occlusal trauma, erosions and concrements on the roots, tooth malposition, the absence of contact point, inadequate interproximal distance of roots and iatrogenic factors. The results revealed that the most frequent etiologic factor in the forming of intrabony periodontal defects was occlusal trauma--55.8%, erosion of the roots--38% and concrements in the roots--34%, as tooth malposition, inadequate interproximal distances of the roots, the absence of contact point and iatrogenic factors. In the forming of 23.5% of intrabony periodontal defects two or more of the studied factors pariticipated. By the analysis of the distribution of etiologic factors by jaw segments, it was concluded that occlusal trauma was the most frequent in upper incisors--61.6%. In upper premolars the most frequent factor was the erosion on the roots--75%, and in the upper molars iatrogenic factors and erosion of the roots--44.4%. In the lower incisors, occlusal trauma was the most frequent--62.5%, in premolars also trauma--35.7%, and concrements of the molars--64.2%. Considering the high incidence the factors associated with chronic inflammation can be extremely significant in the forming of intrabony periodontal defects during parodontopahty.

Alveolar Bone Loss↗

PubMed1996

The fate of teeth transfixed by osteosynthesis screws.

Rigid internal fixation with plates and screws for osteosynthesis of facial fractures and osteotomies in the cranio-maxillofacial skeleton is often undertaken in situations in which the exact position of the underlying tooth roots cannot be determined. Therefore, a screw may be inadvertently placed into a root. There is scant data in the literature addressing the consequences of tooth impingement. This 5-year retrospective study documents the long-term outcome of teeth transfixed by osteosynthesis screws in a series of 387 consecutive facial fractures at a Level I trauma center. The incidence of root impingement per screw was 0.47 percent (13 transfixed teeth per 2340+ screws). Mandibular teeth were more "at risk" than maxillary teeth by a ratio of 10:3. No transfixed teeth became infected or required extraction in this series. In conclusion, inadvertent tooth root impingement by osteosynthesis screws appears to have minimal adverse consequences.

Adult↗

PubMedDate not supplied

[Size of wound area and frequency of alveolitis after tooth extraction].

Electron spin resonance was used to measure out 160 tooth root surfaces. These data represent a measure for wound area sizes after tooth extractions. A comparison of these values with clinical data results in a correlation between the size of wound area and the frequency of inflammatory healing disorders after tooth extractions.

Dry Socket↗

PubMed1990

[Root resorption of vital and endodontically treated teeth in orthodontic movement].

Orthodontic tooth movement frequently induces the resorption of the tooth root, although valuable information concerning the relationship between the root resorption and force magnitude, duration and types of tooth movement and the condition of periodontium obtained. However, it is incompletely known that the situation of candidated tooth itself of orthodontic movement in which pulpectomized non-vital condition influence the process of root resorption and subsequent repairing. Thus, the study was conducted to clarify the effect by the pulpectomy accompanied with tooth movement on the process of root resorption and regeneration of periodontium. A hundred and fifty Wistar rats, weight 180-200 g, 6 weeks old, were used as experimental animals. Prior to experimental tooth movement, first molars of 50 rats were received pulpectomy on both sides followed by filling of root canal (first group) and those of another 50 rats on single side (second group). Maxillary first molars of the other 50 rats were saved as a vital dental pulp control (third group). The first and the third groups of animals were then subjected to experimental tooth movement with the interproximal insertion of elastic rubber as described by Waldo (1953) for 3 days, 1, 2, 3 and 4 weeks. After tooth movement was terminated, animals were sacrificed by ether inhalation or by perfusion of glutaraldehyde fixation solution. The upper jaw from each rat was dissected and prepared specimens for non-decalcified section and light microscopic section. Root resorption and regeneration of cementum were evaluated quantitatively using the modular system for semiautomatic quantitative evaluation of images on the light microscopic section. Occurrence of external root resorption with multinucleated odontoclast associated with experimental tooth movement in pulpectomized tooth were lesser and later than those of vital teeth. These findings suggest that the dental pulp plays an important role in the processes of root resorption and remodeling of cementum associated with orthodontic tooth movement.

Animals↗

PubMed1997

Remineralization of root surfaces demineralized in solutions of differing fluoride levels.

The beneficial effects of fluoride on enamel have been well documented. However, limited data are available concerning the amount of fluoride required for beneficial effects on tooth root. Although studies have shown that fluoride inhibits root demineralization, the aim of this study was to investigate the location, extent and amount of remineralization on root dentin substrates after demineralization has occurred. The root surfaces of extracted human teeth were demineralized in a pure chemical buffer containing varying concentrations of sodium fluoride. After this lesion initiation, the same root sections were then placed into a remineralizing solution. The root sections were characterized after demineralization, and again after remineralization, by polarized light microscopy (PLM) and microradiography (MRG). Lesion depths after the demineralization phase were found to be inversely proportional to the fluoride concentration. When fluoride was present, bands or lines within the body of the lesion were observed with PLM and MRG. Using quantitative MRG, variations in mineral content and distribution were recorded. Examination of the root sections after the remineralization phase showed remineralization to have occurred on the remaining mineral and not on organic matrix devoid of mineral. The amount and location of mineral deposition may be of great significance in the arrestment and treatment of in vivo root surface caries.

Buffers↗

PubMed2002

Application of Lamendin's adult dental aging technique to a diverse skeletal sample.

Lamendin et al. (1) proposed a technique to estimate age at death for adults by analyzing single-rooted teeth. They expressed age as a function of two factors: translucency of the tooth root and periodontosis (gingival regression). In their study, they analyzed 306 singled rooted teeth that were extracted at autopsy from 208 individuals of known age at death, all of whom were considered as having a French ancestry. Their sample consisted of 135 males, 73 females, 198 whites, and 10 blacks. The sample ranged in age from 22 to 90 years of age. By using a simple formulae (A = 0.18 x P + 0.42 x T + 25.53, where A = Age in years, P = Periodontosis height x 100/root height, and T = Transparency height x 100/root height), Lamendin et al. were able to estimate age at death with a mean error of +/- 10 years on their working sample and +/- 8.4 years on a forensic control sample. Lamendin found this technique to work well with a French population, but did not test it outside of that sample area. This study tests the accuracy of this adult aging technique on a more diverse skeletal population, the Terry Collection housed at the Smithsonian's National Museum of Natural History. Our sample consists of 400 teeth from 94 black females, 72 white females, 98 black males, and 95 white males, ranging from 25 to 99 years. Lamendin's technique was applied to this sample to test its applicability to a population not of French origin. Providing results from a diverse skeletal population will aid in establishing the validity of this method to be used in forensic cases, its ideal purpose. Our results suggest that Lamendin's method estimates age fairly accurately outside of the French sample yielding a mean error of 8.2 years, standard deviation 6.9 years, and standard error of the mean 0.34 years. In addition, when ancestry and sex are accounted for, the mean errors are reduced for each group (black females, white females, black males, and white males). Lamendin et al. reported an inter-observer error of 9+/-1.8 and 10+/-2 sears from two independent observers. Forty teeth were randomly remeasured from the Terry Collection in order to assess an intra-observer error. From this retest, an intra-observer error of 6.5 years was detected.

Adult↗

PubMed1990

The histologic evaluation of new attachment in periodontally diseased human roots treated with tetracycline-hydrochloride and fibronectin.

The purpose of this study was to determine how the treatment of human tooth roots with tetracycline-HCl and fibronectin during periodontal surgery influences the attachment of the gingiva to the root surface. Mucoperiosteal flap surgery was performed on 22 teeth with periodontal disease. Teeth were assigned to three groups. Group one received surgery with degranulation and root planing. Group two received surgery with treatment of roots with tetracycline-HCl. Group three received surgery with treatment of roots with tetracycline-HCl and fibronectin. At 90 days, block sections were taken and teeth, gingiva, alveolar bone, and periodontal ligament were evaluated histologically. Controls healed with a long junctional epithelial attachment. Tetracycline and tetracycline with fibronectin groups demonstrated some reattachment, but only within the notches placed in the root at the original level of the bone. There was a trend for greater connective tissue attachment following tetracycline-HCl treatment of roots. The additional application of fibronectin to tetracycline treated roots appeared to partially negate the enhanced connective tissue attachment observed with tetracycline treatment alone.

Acid Etching, Dental↗

PubMed2000

Studies of dental root surface caries. 2: The role of cementum in root surface caries.

Artificial caries lesions were produced in roots of teeth using an acetate buffer system, when the layer of cementum was either normal in thickness, excessively thickened by hypercementosis, or had been removed completely. The rates of lesion progression were measured in each case using polarized light microscopy to measure lesion depth. Analysis of calcium (Ca) and phosphorus (P) loss during the demineralizing process was carried out. The removal of cementum was found to significantly increase the initial rate of penetration of the lesion into the root, although this rate progressively reduced to a level consistent with that found in normal roots after seven days of demineralization. The overall depth remained consistently greater than that observed in normal roots, or when lesions were produced entirely within hyperplastic cementum. Chemical analysis also showed removal of cementum resulted in an initial doubling of the Ca and P lost from the root surface. Prior direct exposure of segments of normal roots to the oral environment was found not to significantly alter the rate of artificial lesion progression, in comparison with that in the originally protected segment of the root surface. It was concluded that an intact cementum layer has the intrinsic ability to protect the underlying dentine of exposed tooth roots against acidic demineralization and that prior exposure to the oral environment does not significantly alter this ability.

Calcium↗

PubMed1995

Crown amputation with intentional root retention for advanced feline resorptive lesions--a clinical study.

Whole tooth extraction is generally considered to be the treatment of choice for teeth with advanced feline external odontoclastic resorptive lesions. These teeth often have both a weakened, brittle crown and radicular ankylosis. These two factors cause frustration and sometimes complications during attempts at extraction. This study investigated the alternative of intentionally leaving part or all of non-pathologic tooth roots in situ to prevent iatrogenic trauma to the patient, loss of alveolar bone, and prolonged healing of surgical defects. Fifty one roots from 23 teeth were radiographed 5-36 months following elective root retention; continued resorption without surrounding bony reaction was seen in almost all cases. In one cat, the roots retained normal periodontal ligament one year later, and in another cat that developed severe stomatitis, the intentionally retained roots were extracted at the same time that the remaining molar teeth were extracted.

Alveolar Bone Loss↗

PubMed1986

Relationship of maxillary molar root angulation and palatal vault height.

If the vertical angulation of maxillary molar roots could be reliably predicted, this might affect the choice of roots resection procedures. In an attempt to develop this prediction, angulation of palatal roots was compared to palatal vault height. Human cadaveric maxillae with molars were sectioned faciopalatally through each tooth root to the palatal midline and photographed. Root angles and palatal height were measured on the photographs in relation to a reference line connecting buccal and palatal cementoenamel junctions (CEJ). Palatal vault heights were classified as low, medium, or high according to the perpendicular distance from the midpalatal suture to the reference line. Root angles were subtended by a line following the length of pulp canals and perpendicular to the CEJ reference. Analysis by Spearman's Rank Correlation Coefficient demonstrated a weak nonsignificant relationship between palatal vault height and the angulation of the various maxillary molar roots. Thus, palatal vault height would not be a reliable predictor of root angulation if this were to be used as a basis for root retention.

Adult↗

PubMed1991

[The rate of the eruption of human teeth. A review].

The speed that a tooth bud or growing tooth attains on its way to the level of occlusion merits biological and clinical interest. In this work, all data available in the literature related to the eruptive movement of the various permanent teeth in man, both prior and after their clinical emergence in the oral cavity, have been gathered and recalculated in rates of movement per day. For comparative purposes, the rates of migration of nonerupted teeth, of bone resorption and bone apposition, as well as the rate of elongation of growing tooth roots were also collected from the literature. The standardized data (rates in micron/day) revealed the intraosseous movements of tooth buds and growing teeth are dependent and limited in speed by the rates of bone resorption and bone apposition. The extra-alveolar movement of clinically visible tooth crowns on their course of prefunctional eruption occurs at a much higher speed which probably results from a combination of the rate of bone apposition in the apical region and the rate of root elongation. These findings are discussed in connection with our present knowledge on the mechanisms of tooth eruption.

Bone Development↗

PubMedDate not supplied

Benign cementoblastoma: a clinical case of conservative surgical treatment of the involved tooth.

The benign cementoblastoma (BC) or ''true'' cementoma is a rare benign neoplasm arising from the odontogenic ectomesenchyme and representing about 1% to 6.2% of all odontogenic tumors. The BC more frequently affects young males in an age range of 20-30 years, occurring in the mandible about 3 times more than in the maxilla, and it is always physically attached to the tooth roots. This tumor is often asymptomatic until it produces pain, expansion or swelling of the jaw segment or compression of the inferior alveolar nerve. Early diagnosis is essential to save the tooth by enucleating the tumor, filling the root canals and apicectomy or curettage of the affected roots. A case of BC embedding the mandibular first right molar and resorbing the vestibular cortical bone, in a 48 year-old male, is reported. The radiographic examination showed a well-defined mixed-density unilocular mass, confluent with both the tooth roots of the mandibular first molar and surrounded by a radiolucent rim. A combined endodontic-surgical treatment was performed with the aim to remove the tumor while saving the tooth. Histological findings, differential diagnosis and surgical treatment of the tumor are discussed and compared with similar cases in the literature.

Dental Cementum↗

PubMed1991

Potential attachment area of the fourth maxillary premolar in dogs.

Tooth root and root trunk surface area measurements were made on 20 permanent fourth maxillary premolar (P4) teeth randomly harvested from canine cadaver specimens. Mean root surface area for all 20 teeth was 562.8 +/- 124.9 mm2. Cumulative surface areas of the mesiopalatal, mesiobuccal, and distal roots were 113.8 +/- 29.0 mm2, 138.5 +/- 34.6 mm2, and 180.8 +/- 39.9 mm2, respectively. The mesial root trunk and distal root trunk surface areas were 60.0 +/- 17.5 mm2 and 72.1 +/- 33.2 mm2, respectively. There was not a significant difference between the root surface area of the mesial root trunk and distal root trunk; however, all other root surface area measurements were significantly different (P less than 0.01). Cumulative individual root surface area (distal root + mesiobuccal root + mesiopalatal root) was 76% of total root surface area. The distal root surface area contributed most to total root surface area (32.1%) and cumulative individual root surface area (41.7%). Observation of the linear variation of percentage of root surface area revealed 40.8% of the total root surface area to be in the portion located between 5 and 9 mm apical to the most coronal aspect of the cementoenamel junction. The mesiobuccal root and distal root were cylindrical compared with the flattened, concave shape of the mesiopalatal root.

Animals↗