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At least 1,099 records · Page 61Linked to original sources
PubMed1989

Population variation in tooth, jaw, and root size: a radiographic study of two populations in a high-attrition environment.

Radiographs were taken of the jaws of skeletal remains of two populations of different-phenotype Prehistoric Australians from Roonka and Early New Zealanders (Maoris). On these radiographs crown, root, and corpus size were measured. Corpus height was subdivided into alveolar bone height, defined as the bone superior to the mandibular canal, and basal bone height, defined as that inferior to the mandibular canal. Both between and within the two populations there was a significant and negative correlation between crown size and corpus height. The differences between the two populations in corpus height were associated with differences in alveolar bone height rather than basal bone height and support hypotheses associating continued eruption of adult teeth with growth of the alveolar bone. The findings also support previous studies that have shown only a low correlation between crown size, root size, and corpus height.

Australia↗
PubMed2003

[Clinical studies of calcium hydroxide disinfecting infectious root canal of deciduous tooth].

OBJECTIVE: To search for a more ideal way to disinfect infectious root canal of deciduous tooth. METHODS: According to bacterial occurrence and clinical effect, 40 cases of infectious root canal of deciduous teeth disinfected with Ca(OH)2 were investigated, the other 40 cases with traditional way of using FC and CP respectively, were used as the control. RESULTS: Fist of all, the bacteria of deciduous tooth infectious root canal were same as the bacteria of permanent tooth infectious root canal. Secondly, Ca(OH)2 was stronger in disinfecting deciduous tooth infectious root canal. Thirdly, so far as sterilization was concerned, Ca(OH)2 had the same disinfectant as FC, and was better than CP, but FC had some irritation and poisonous side-effects to periodical tissue. So Ca(OH)2 was safe and effective for deciduous tooth infectious root canal. CONCLUSION: It was a more ideal way to disinfect deciduous tooth infectious root canal by Ca(OH)2.

Calcium Hydroxide↗
PubMed2004

Effects of local administration of clodronate on orthodontic tooth movement and root resorption in rats.

Clodronate, a non-N-containing bisphosphonate, strongly inhibits bone resorption and also has anti-inflammatory properties. The purpose of this study was to examine the effect of the local administration of clodronate on orthodontic tooth movement. Both the right and left upper first molars of 26 7-week-old male Wistar rats were moved buccally with a standardized expansion spring. Clodronate solution was injected into the sub-periosteum area adjacent to the left upper molar every third day during the experimental period. The right first molar served as the control. Local injection of clodronate caused a significant (P < 0.001) and dose-dependent reduction in tooth movement in the rats. The number of osteoclasts on the clodronate-injected side was significantly less (P < 0.01) than on the control side. Local clodronate also inhibited root resorption incident to tooth movement. These results suggest that localized use of clodronate could be a useful therapeutic adjunct in orthodontic treatment.

Alveolar Process↗
PubMed1996

The effects of a four-fold increased orthodontic force magnitude on tooth movement and root resorptions. An intra-individual study in adolescents.

This clinical and histological study was designed as an intra-individual study to investigate the effect on tooth movements and adverse tissue reactions (root resorption) when a fixed orthodontic appliance was activated with a controlled, continuous force of 50 cN (approximately equal to 50 g) or with a four-fold larger force (200 cN approximately equal to 200 g). The first premolar on both sides of the maxilla in eight individuals, six boys and two girls (mean age 13.0 years), was moved buccally during 7 weeks with 50 cN and 200 cN alternately on the right or left size. During the first week a force reduction of 18 and 28 per cent (on average) was registered in the 50 cN and 200 cN group respectively. Tooth movements were studied by means of dental casts using a coordinate measuring machine. The magnitude of the mean horizontal crown movement increased 50 per cent when a force of 200 cN was applied compared with a 50 cN force (3.4-5.1 mm on average) and the difference was significant. Root resorptions were registered in histological sections of the extracted test teeth with no significant difference in frequency or severity between the two forces used. Individual variations were large regarding both tooth movement and root resorption. Possible reasons to explain the results as well as the clinical implications of the findings are discussed.

Adolescent↗
PubMed1990

[Changes of vibration frequency due to root resorption of deciduous tooth].

The purpose of this study was to investigate the changes of vibration frequency of a deciduous tooth due to physiological root resorption. The author developed an analysis system for tooth vibration by applying an impact-hammer to the tooth. Peak frequency (Hz) of the tooth stimulated by the impact-hammer was observed by the analysis system. The following results were obtained: 1) Peak frequency of the tooth vibration shifted to a lower range according to the root resorption both in vitro (simulation model) and in vivo (15 children) and a high positive correlation was found between the peak frequency and the crown-root length ratio (r = 0.840). 2) A cause of the frequency shift to the lower range was not related to the tooth weight but to the change of tooth gravity due to the root resorption. 3) It was considered that the vibration analysis system could be useful on measuring tooth mobility in vivo and in clinic as well.

Child↗
PubMed2004

Scanning electron microscopic investigation of incidence, location, and size of accessory foramina in primary and permanent molars.

OBJECTIVE: The purpose of this study was to determine and compare the incidence, location, and size of accessory foramina in the furcation region of permanent and primary molars. METHOD AND MATERIALS: A random sample of 100 extracted human permanent maxillary and mandibular first and second molars (25 teeth of each type) and a random sample of 100 extracted human primary maxillary and mandibular molars (50 teeth of each type) were used. The crowns and roots of each tooth were removed at a point 1.5 mm apical to the external furcation region, and a second cut was made at a point 1 mm apical to the cementoenamel junction. The specimens were examined using scanning electron microscopy at magnifications ranging from x 10 to x 1,250. The incidence, location, and size of accessory foramina were documented and statistically analyzed. RESULTS: Of the 100 permanent molars examined, 79% had accessory foramina with diameters ranging from 10 microm to 200 microm. Accessory foramina were present in 94% of the primary molars, with diameters varying from 10 microm to 360 microm. The incidence of accessory foramina was significantly higher in primary than in permanent molars. CONCLUSION: The presence of accessory foramina with large diameters may imply that an inflammatory process can spread from pulpal to periodontal tissues and vice versa.

Dental Pulp Cavity↗
PubMed2006

Biocompatibility of Beta-tricalcium phosphate root replicas in porcine tooth extraction sockets - a correlative histological, ultrastructural, and x-ray microanalytical pilot study.

This investigation studies porcine tissue response in tooth extraction sockets treated with root replicas made out of Beta-tricalcium phosphate (Beta-TCP; Beta-Ca(3)(PO(4))(2)) granules, molded and held together by thermal fusion of a thin film of polyglycolic-polylactic acid copolymer. Six left mandibular third incisors (n (1)/4 6) of experimental pigs are treated with the root replicas and four contralateral incisors are used as nontreated controls (n (1)/4 4). Two animals each were killed at 20, 40, and 60 weeks of observation periods. The mandibular jaw segments were prepared in toto for light microscopy by resin embedding and serial ground sectioning. Additionally, one Beta-TCP-treated socket at 60 weeks was thoroughly investigated by correlative light, electron microscopic and electron probe X-ray microanalysis to assess the bio-absorbability and host removal of the replica material from the implant site. The extraction wounds of the animals healed satisfactorily with very little histologically observable differences in the healing pattern of the test and control sites. The Beta-TCP was completely removed from extracellular sites, but at 60 weeks, remnants of it were found in the cytoplasm of multinucleated giant cells. The root replicas made out of Beta-TCP were biocompatible and bioabsorbable. Osseous healing occurred both in the test and control sockets, but the healing process was delayed due to the presence of Beta-TCP particles.

Animals↗
PubMed1995

Continuous versus interrupted continuous orthodontic force related to early tooth movement and root resorption.

The aim of the present clinical investigation was to assess the effects of continuous and interrupted continuous forces of the same magnitude (50 cN = 50 g) on orthodontic tooth movement and related adverse tissue reactions, i.e., root resorption. Thirty-two maxillary first premolars in 16 patients, 8 boys and 8 girls (mean age 13.9 years), were moved buccally by means of a fixed orthodontic appliance with a sectional arch. The patients were divided into two groups of 8, for experimental periods of 4 and 7 weeks. The continuous force was checked and reactivated weekly to 50 cN. The interrupted continuous force applied to the contralateral premolars was left uncontrolled for 3 weeks, after which the arch was made passive for 1 week for tissue rest and recovery. Tooth movements were studied on dental casts using a coordinate measuring machine (Validator 100, TESA SA, Renens, Switzerland). Horizontal tooth movement with continuous force was more effective than with interrupted continuous force after 7 weeks. Histological sections of the experimental teeth, however, showed no difference in the amount or severity of root resorption between the two forces. Individual variations in both the magnitude of tooth movement and the amount and severity of root resorption for both of the two force systems were great.

Adolescent↗
PubMed1984

Root resorption and tooth movement in orthodontically treated, calcium-deficient, and lactating rats.

Previous studies have shown that chronic dietary deficiency of calcium can result in more rapid orthodontic tooth movement. The purposes of this study were to confirm that finding in a calcium-deficient, lactating rat model and to quantify the degree to which the area of root surface resorption is affected by these conditions. Thirty-five adult female Sprague-Dawley rats were divided into two groups: (1) nonlactating animals on a control diet and (2) lactating animals on a calcium-deficient diet. A 60-gm orthodontic force designed to tip maxillary molars mesially was applied for varying times. At sacrifice, tooth movement was quantified by measuring the space created between maxillary molars; percent bone ash was measured for each humerus, and root surface resorption was estimated by means of a morphometric technique to measure the area of cratering on the mesial roots of first molars. Both groups showed a typical two-phased tooth movement cycle lasting for 10 days, although the magnitude of movement was significantly greater (p less than 0.001) in the test animals. The "humerus" test from animals exhibited a significantly decreased (p less than 0.001) fat-free dry weight, ash, and percent ash weight. The test group also displayed a significantly reduced percent area of root surface resorption (p less than 0.05) by 7 and 10 days following appliance activation. These findings confirm earlier observations that lactation, coupled with calcium deficiency, will produce decreased bone density which is consistent with increased parathyroid hormone secretion.(ABSTRACT TRUNCATED AT 250 WORDS)

Activator Appliances↗
PubMed1997

Radiography of spontaneous periodontitis in dogs.

The pattern and distribution of periodontitis were investigated in 162 randomly selected dogs available for necropsy in veterinary practice. There were 82 males and 80 females of 50 different breeds (150 dogs were pure-bred and 12 were mongrels, aged between 7 months and 14 yr. Presence of periodontitis was determined by assessment of alveolar bone loss on radiographs of the skulls and jaws. Periodontitis occurred frequently with increasing age, although the prevalence varied markedly among and within different breeds. Of the breeds most represented in the sample, periodontitis was most frequently seen in poodles and dachshunds but was rarely recognized in German shepherd dogs. Regardless of age, the vast majority of the dogs displayed either one or both of two different radiographic patterns of alveolar bone loss. One pattern was characterized by slight, horizontal alveolar bone loss involving interradicular and interdental areas. The other pattern was one of predominantly crater-like, or narrow, vertical bone defects which, when advanced, often extended around a single root or tooth to surround the root apices. The two types of patterns did not seem to be breed-dependent. The posterior maxillary and mandibular premolars and molars were the most frequently affected teeth. Alveolar bone loss was most severe in the maxilla, while corresponding bone loss in the mandible was more often related to increasing age.

Age Factors↗
PubMedDate not supplied

Root intrusion in tooth-implant combination cases.

The various proposed etiologies for root intrusion in tooth-implant combination cases are discussed. Clinical examples of root intrusion are illustrated. Advantages and disadvantages of nonrigid connector and coping/suprastructure techniques are presented.

Dental Abutments↗
PubMed1990

Clinical and histological findings in ligature-induced experimental periodontitis in dogs. A pilot study.

Prior to experimental periodontal regenerative procedures in animals, the process of destruction due to periodontitis is often simulated by placing ligatures around the necks of teeth. 2 models, one using cotton floss ligatures and the other elastic rubber ligatures, have been widely used. The aim of this study was to compare these 2 methods using clinical and histometric criteria. Premolars on both sides of the mandibular jaw were used in 2 beagle dogs. Periodontal tissue breakdown was induced during a 48-day period using cotton floss ligatures on one side of the mandible and contra-laterally by elastic rubber ligatures. At weekly intervals, the ligatures were changed and pocket depth and loss of probing attachment were recorded. All the ligatures were removed after 7 weeks. The animals were fed a soft, plaque-promoting diet during the experimental period. 20 days after ligature removal, the teeth were hemisected and the 2 roots extracted. From each tooth, 1 root was prepared for scanning electron microscopy and one for light microscopy. At the time of extraction, no differences regarding pocket depth or probing attachment level were found between the 2 groups. Root resorption was observed in all elastic ligature teeth, whereas only minor alterations at the root surface were observed on cotton ligature teeth. This finding may be of particular interest to investigators designing studies evaluating the healing sequalae of regenerative surgery in animals. As was observed in this study, root resorption can already be present in the pre-experimental phase of periodontal tissue breakdown, particularly if elastic ligatures are used.

Animals↗
PubMed1993

Radicular cyst affecting a root-filled human tooth: a long-term post-treatment follow-up.

Apical periodontitis is caused primarily by microorganisms residing in the root canals of affected teeth. Nevertheless, there is convincing evidence implicating other independent factors that adversely affect the outcome of conventional root canal therapy. In this paper, morphological evidence is presented in support of the potential role of two endogenous factors that may interfere with post-endodontic healing of the periapex. The specimens consisted of a surgical biopsy of an asymptomatic periapical lesion which persisted for a follow-up period of 44 months. The biopsy was processed for correlated light and electron microscopy. The lesion was characterized by the presence of a large central lumen lined by a stratified squamous epithelium. The most striking feature of the lesion was the presence of vast numbers of cholesterol crystals which congregated in the connective tissue surrounding the cyst cavity. Extensive light and electron microscopic investigation of the apical part of the root canal and the lesion failed to reveal the presence of microorganisms. These findings strongly suggest that intrinsic factors like the accumulation of certain tissue break-down products such as cholesterol crystals, and the cystic condition of the lesion itself, can adversely affect the healing process of the periapex following root canal therapy. Consequently, such apical lesions can remain refractory to conventional endodontic therapy for long periods of time.

Adult↗