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At least 1,189 records · Page 66Linked to original sources
PubMed1982

Intentional replantation of a maxillary molar. A 4-year follow-up.

A 4-year follow-up of a case treated by intentional replantation has been presented. A maxillary molar with a metal core was diagnosed as having acute apical periodontitis, endodontic treatment was determined to be impractical, and the tooth was extracted. Three roots canals which could not be detected roentgenologically were discovered and, after apicoectomy and reversed amalgam filling, the tooth was replanted in its socket. The follow-up reveals periapical repair with no signs of root resorption or ankylosis.

Adult↗
PubMed1978

Radiological features of mandibular primordial cysts. (Keratocysts).

Primordial cysts (keratocysts) have been shown to have a greater tendency to recurrence than other jaw cysts. Some radiological features may assist in establishing the diagnosis. Thirteen mandibular primordial cysts have been studied radiologically in detail. Characteristic features are extension along the medulla with minimal expansion except in young children. Margins are generally sharply demaracated and either smooth or scalloped. Cortical resorption occurs before expansion. The cysts may displace adjacent teeth, particularly when unerupted, but generally do not produce root resorption. They may displace the neurovascular bundle. Antero-posterior dimensions in this series ranged from 28 to 77 mm, with a mean of 50 mm.

Adolescent↗
PubMed2004

The accuracy of the cementoenamel junction identification on periapical films.

In the study of orthodontically induced inflammatory root resorption, many researchers use the cementoenamel junction (CEJ) as a bisecting reference point to measure the amount of root shortening. The accuracy of the identification of the CEJ point might affect the conclusions of those studies. This study aims to find the effects of angular changes between the tooth and the film on the validity and reproducibility of identifying three different CEJ points, ie, the most apical CEJ point between the crown and the root, the most mesial CEJ point, and the most distal CEJ point. An extracted maxillary central incisor was placed in a special jig and radiographed at four different tooth to film angulations. Eight examiners were asked to identify the buccal and palatal CEJ, whereas six examiners were asked to identify the mesial and distal CEJ points, all on a computer monitor. The distances between the identified points and the apex were computed and compared with the actual ones. The angular changes between the tooth and the film did have a statistically significant effect on the identification of some of these CEJ points. The difference was significant on the identification of the buccal and palatal points but not on the mesial and the distal ones.

Analysis of Variance↗
PubMed1992

Odontoclastic resorption at the pulpal surface of coronal dentin prior to the shedding of human deciduous teeth.

Histological and histochemical observations of more than 150 extracted human deciduous teeth revealed that, prior to shedding, odontoclastic resorption as a rule takes place at the pulpal surface of coronal dentin. We also found that this phenomenon occurs in all kinds of deciduous teeth. The process of this internal resorption of coronal dentin of deciduous teeth clearly showed time-related histological changes. During the time the roots were actively being resorbed, the pulpal tissue retained its normal structure. However, when root resorption neared completion, inflammatory cells started to gradually infiltrate into the pulp, and odontoblasts began to degenerate. After that, multinucleate odontoclasts appeared, and resorption proceeded from the predentin to the dentin. The odontoclastic activity was initially detected only on the pulpal surface at the bottom areas of the crown. It gradually spread towards the pulpal horn regions along the wall of the pulp chamber. However, this internal resorption of coronal dentin did not continue until the teeth were finally shed. After the elimination of resorption, the resorbed dentin surface was repaired by a cementum-like deposition or covered with fibrous connective tissue.

Cuspid↗
PubMed1990

Biphasic calcium phosphate ceramic combined with fibrillar collagen with and without citric acid conditioning in the treatment of periodontal osseous defects.

The purpose of this study is to determine whether the combination of biphasic calcium phosphate ceramic (BCP) and collagen and citric acid root conditioning would promote accelerated new attachment of periodontal tissue to the root surface in dogs. Intrabony defects were surgically produced for each animal and were made chronic for 16 weeks. These defects were assigned to two study treatment and one control group: ceramic-collagen without citric acid (CO-CE); ceramic-collagen with citric acid (CO-CE-CA); and control (surgical debridement and root planing only). Results showed that all groups gained new attachment level as demonstrated both clinically and histometrically. The treatment groups showed a significant mean gain greater than the control (P less than .005), but no significant difference was found between treatment groups. Small areas of ankylosis was also found in both treatments but there was no evidence of active root resorption. It is concluded that the use of combined BCP and fibrillar collagen is beneficial in promoting new attachment of periodontal tissues to the root surface in dogs. Although citric acid root conditioning did as well or better than ceramic and collagen alone, its benefits are still speculative and need further experimentation.

Animals↗
PubMed1982

Factors influencing periodontal repair and regeneration.

The purpose of the present study was to evaluate independently the regeneration capacity of a reduced periodontium, and the potential for new connective tissue attachment to a periodontally exposed root surface. A reduced periodontium was produced around a maxillary central incisor in two Rhesus monkeys using orthodontic elastics. The regeneration capacity of this reduced peridontium was investigated by extracting the periodontally involved tooth and transplanting into the socket the contralateral incisor which had a normal periodontium. The potential for new connective tissue attachment to a periodontally exposed root surface was evaluated by transplanting an exposed root into a normal periodontium. These exposed roots were the incisors extracted from the reduced peridontium. Control specimens were obtained by extracting and reimplanting or transplanting the remaining maxillary and mandibular incisors. Forty days after the experimental procedures, block sections were removed and prepared for histologic analysis. The exposed root surface that had been put into the normal periodontium was lined with epithelium interposed between root surface and alveolar bone. The normal root surface that had been put into the reduced periodontium had connective tissue reattachment in the periodontal ligament and supracrestal regions. Areas of ankylosis and root resorption were present in all specimens, as was new cementum in the periodontal ligament region. The results indicated that root surface alterations, rather than presence of a reduced periodontium, inhibited new connective tissue attachment.

Animals↗
PubMed1989

The interrelationship between the root surface and alveolar bone of the replanted avulsed tooth after etching.

It has been suggested that removal of the damaged nonvital periodontal ligament (PDL) may result in slower destruction of tooth substance following replantation of teeth. It has also been suggested that citric acid conditioning of surgically exposed dentin may enhance connective tissue attachment on root surfaces. The aim of this study was to examine the interrelationship between the acid etched root surface of the replanted tooth and the alveolar bone. Forty-five available anterior teeth from six monkeys were divided into 3 groups in this experiment. All teeth were extracted and dried for 2 hrs. In the first group the teeth were replanted immediately after endodontic therapy. The teeth in the second group were replanted after immersion in 10% sodium hypochlorite and subsequently irrigation with normal saline. In the third group, the cementum and necrotic PDL were removed by grinding the root surfaces which were then treated with citric acid (PH = 1) for 3 minutes followed by normal saline irrigation. All teeth were replanted without splinting and were subjected to histological examination at 12 week post-replantation. Close apposition of collagen fibrils of the new connective tissue to the exposed root surface was observed in most cases in the second and third group, although bony ankylosis and inflammatory root resorptions were also found in some areas. Teeth in the first group, the control experiment, had much more replacement and inflammatory resorptions. Then the result suggested that demineralization with citric acid on the denuded avulsed tooth prior to replantation may decrease the chance of replacement resorption and result in fibrous adhesion to the alveolar bone.

Adhesiveness↗
PubMed1986

In vivo differentiation of progenitor cells of the periodontal ligament. An experimental study using physical barriers.

The present study was designed to test the hypothesis that during regeneration of cementum, the progenitor cells from periodontal ligament must come in contact with root dentin in order to differentiate into cementoblasts. After reflecting mucoperiosteal flaps, fenestration wounds were made in the buccal cortical plates of mandibular canines in 6 beagle dogs. The exposed root surfaces were curretted to remove all cementum. The exposed root surface on one side was demineralized with citric acid while the contralateral wound had saline treatment. The exposed root surfaces were then dried and pieces of Nuclepore membrane (pore size 0.1 mu) were attached to part of the exposed root surface to prevent contact of progenitor cells with root dentin. The fenestration wounds were then covered with Millipore filter to facilitate the population of wounds by progenitor cells from the periodontal ligament. Histologic analysis was performed after 3 months of healing. In specimens where the Nuclepore membrane had remained attached to root dentin, no new cementum was seen over the membrane. At the borders of the wounds and in specimens where the Nuclepore membrane had detached from root dentin, new connective tissue attachment was consistently seen. Also, root resorption was very rarely observed in both the acid-treated and control specimens. The present findings suggest that contact with root dentin may be necessary for progenitor cell differentiation into formative cells like cementoblasts.

Animals↗
PubMed1996

A dual approach to bleaching.

A procedure is presented which combines the walking bleach and the external thermocatylitic bleaching technique. This maximizes the bleaching potential of each and minimizes the possibility of subsequent external root resorption.

Adult↗
PubMed1982

Intraalveolar transplantation. (I). The use of autologous bone transplants in the periapical region.

Intraalveolar transplantation of teeth with unfavourable cervical root fractures were performed in 15 patients. The roots were surgically extruded on an average 4.5 mm, and autologous bone transplants were placed above the apical part to support the root. Temporary endodontic therapy was carried out before the transplantation in 10 patients and 3 weeks after transplantation in 2 patients. 3 of the teeth had old root fillings. Postoperative controls were made weekly during the first month, after 3 months, 6 months, 1 and 2 years. The roots had become stable in most cases after 3 weeks. The mobility grade was dependent on the extent of extrusion. Radiographic controls showed formation of a normal periodontal space around the roots after 3 months, but also minor root resorption in the most apical part in 10 of the cases. The resorption was, however, not progressive in nature and was limited to the apical part. Remodelling of the marginal bone contour around the transplanted roots was evident in 11 patients. Periapical destructions were found in 3 patients at the 2-year control. Crown therapy was carried out with due attention to the special prosthetic problems associated with preparation of small remaining root fragments with unfavourable crown/root ratio.

Adolescent↗
PubMed1999

Analysis of stress in the periodontium of the maxillary first molar with a three-dimensional finite element model.

The aim of this study was to simulate the stress response in the periodontium of the maxillary first molar to different moment to force ratios, and to determine the moment to force ratio for translational movement of the tooth by means of the finite element method. The three-dimensional finite element model of the maxillary first molar consisted of 3097 nodes and 2521 isoparametric eight-node solid elements. The model was designed to dissect the periodontal ligament, root, and alveolar bone separately. The results demonstrate the sensitivity of the periodontium to load changes. The stress pattern in the periodontal ligament for a distalizing force without counterbalancing moments showed high concentration at the cervical level of the distobuccal root due to tipping and rotation of the tooth. After various counterrotation as well as countertipping moments were applied, an even distribution of low compression on the distal side of the periodontal ligament was obtained at a countertipping moment to force ratio of 9:1 and a counterrotation moment to force ratio of 5:1. This lower and uniform stress in the periodontal ligament implies that a translational tooth movement may be achieved. Furthermore, high stress concentration was observed on the root surface at the furcation level in contrast with anterior teeth reported to display high concentration at the apex. This result may suggest that the root morphology of the maxillary first molar makes it less susceptible to apical root resorption relative to anterior teeth during tooth movement. The stress patterns in the periodontal ligament corresponded with the load types; those on the root appeared to be highly affected by bending and the high stiffness of the root.

Alveolar Process↗
PubMed1988

Periodontal wound healing responses to varying oxygen concentrations and atmospheric pressures.

Oxygen effects on healing gingival wedge excisions were tested using Sprague-Dawley rats. 40 operated controls were maintained at normal pressure in room air. 3 experimental groups of 40 rats each were exposed for 90 min daily to one of the following: (1) 20.8% oxygen at 2.4 atmospheres pressure, (2) 100% oxygen at 1 atmosphere, or (3) 100% oxygen at 2.4 atmospheres. 5 animals in each group were sacrificed at the following times: 30, 54, 78 h and weeks 1, 2, 3, 6 and 12. Histometric analysis was performed using light microscopy. The connective tissue healing above a reference notch on the maxillary first molar mesial root was assessed. The controls failed to show healing comparable to experimental animals until the end of 2 weeks. Enhanced connective tissue healing above the notch was most significant (p less than or equal to 0.05) in the 2.4 atmospheres pressure groups at 3 and 6 weeks when compared to controls. However, by 12 weeks, no significant differences could be detected. New cementum formation was rare and occasional root resorption was observed. Early connective tissue adaptation does not imply eventual attachment as epithelial downgrowth progressively displaced the connective tissue adjacent to the root in both experimental and control groups of this study.

Animals↗
PubMed1994

Effect of root canal treatments on dentin permeability.

Calcium hydroxide has been used to slow or reverse external root resorption subsequent to trauma. In this study, an experimental model was established to study the diffusion of calcium ions from the canal to the root periphery after various intracanal treatments. Analyses of calcium ion concentrations from extraradicular samples revealed that dentin specimens varied in their rates of diffusion of calcium and that treatment of the canals with various agents affected the amounts of calcium recovered.

Analysis of Variance↗
PubMed2005

Immediate implant placement: diagnosis, treatment planning and treatment steps/or successful outcomes.

Diagnosis and treatment planning are key factors in achieving successful outcomes after placing and restoring implants placed immediately after tooth extraction. The efficacy of immediate implant placement has been established and shown to be predictable if reasonable guidelines are followed. Some or all of the following suggestions, depending on individual circumstances should be considered when evaluating a patient for dental implants: thorough medical and dental histories, clinical photographs, study casts, periapical and panogram radiographs, as well as a linear tomography or computerized tomography of the proposed implant sites. Reasons for tooth extraction include, but are not limited to, insufficient crown to root ratios, remaining root length, periodontal attachment levels, periodontal health of teeth adjacent to the proposed implant sites, unrestorable caries, root fractures with large endodontic posts, root resorption, teeth with deep furcation invasions being considered as abutments for fixed partial dentures, and questionable teeth in need of endodontic retreatment. Teeth requiring root amputations, hemisections or advanced periodontal procedures may have a questionable prognosis, and patients should be given the implant option before these procedures are implemented. Similarly, nonvital teeth, fractured at the gingival margin with roots shorter than 13 mm should be considered for the implant option. This review will describe the steps for immediate implant placement at the time of extraction as well as the "gap" and socket preservation.

Animals↗
PubMed1985

Intraalveolar transplantation of teeth with crown-root fractures.

Intraalveolar transplantation using a simple extraction technique with extrusion of the root sufficiently to allow crown preparation was performed in 23 cases of crown-root fractures. A normal periodontal membrane was present after three months in all cases. Signs of superficial root resorption were observed in two cases, and small periapical radiolucencies were seen in another two, probably as a reaction to the presence of excess root-filling material. Minor remodeling of the marginal bone adjacent to the extruded roots was observed in eight cases.

Adult↗
PubMed2003

Differentiation and functions of osteoclasts and odontoclasts in mineralized tissue resorption.

The differentiation and functions of osteoclasts (OC) are regulated by osteoblast-derived factors such as receptor activator of NFKB ligand (RANKL) that stimulates OC formation, and a novel secreted member of the TNF receptor superfamily, osteoprotegerin (OPG), that negatively regulates osteoclastogenesis. In examination of the preosteoclast (pOC) culture, pOCs formed without any additives expressed tartrate-resistant acid phosphatase (TRAP), but showed little resorptive activity. pOC treated with RANKL became TRAP-positive OC, which expressed intense vacuolar-type H(+)-ATPase and exhibited prominent resorptive activity. Such effects of RANKL on pOC were completely inhibited by addition of OPG. OPG inhibited ruffled border formation in mature OC and reduced their resorptive activity, and also induced apoptosis of some OC. Although OPG administration significantly reduced trabecular bone loss in the femurs of ovariectomized (OVX) mice, the number of TRAP-positive OC in OPG-administered OVX mice was not significantly decreased. Rather, OPG administration caused the disappearance of ruffled borders and decreased H(+)-ATPase expression in most OC. OPG deficiency causes severe osteoporosis. We also examined RANKL localization and OC induction in periodontal ligament (PDL) during experimental movement of incisors in OPG-deficient mice. Compared to wild-type OPG (+/+) littermates, after force application, TRAP-positive OC were markedly increased in the PDL and alveolar bone was severely destroyed in OPG-deficient mice. In both wild-type and OPG-deficient mice, RANKL expression in osteoblasts and fibroblasts became stronger by force application. These in vitro and in vivo studies suggest that RANKL and OPG are important regulators of not only the terminal differentiation of OC but also their resorptive function. To determine resorptive functions of OC, we further examined the effects of specific inhibitors of H(+)-ATPase, bafilomycin A1, and lysosomal cysteine proteinases (cathepsins), E-64, on the ultrastructure, expression of these enzymes and resorptive functions of cultured OC. In bafilomycin A1-treated cultures, OC lacked ruffled borders, and H(+)-ATPase expression and resorptive activity were significantly diminished. E-64 treatment did not affect the ultrastructure and the expression of enzyme molecules in OC, but significantly reduced resorption lacuna formation, by inhibition of cathepsin activity. Lastly, we examined the expression of H(+)-ATPase, cathepsin K, and matrix metalloproteinase-9 in odontoclasts (OdC) during physiological root resorption in human deciduous teeth, and found that there were no differences in the expression of these molecules between OC and OdC. RANKL was also detected in stromal cells located on resorbing dentine surfaces. This suggests that there is a common mechanism in cellular resorption of mineralized tissues such as bone and teeth.

Acid Phosphatase↗
PubMed1998

Cortical bone remodeling/tooth movement ratio during maxillary incisor retraction with tip versus torque movements.

The validity of the postulate "bone traces tooth movement" was examined on 40 Angle Cl II cases. It was hypothesized that a 1:1 cortical bone remodeling/tooth movement ratio is preserved during maxillary incisor retraction. The sample was divided into retraction with tip (13 patients), retraction with torque (18 patients), and control (9 patients) groups. Two time point cephalograms were analyzed with two superimposition techniques, SN at S and a newly developed static tooth analysis, with the maxillary left central incisor serving as a reference object. In both retraction with tip and retraction with torque groups, the postulate bone traces tooth movement was not preserved and a bone remodeling/tooth movement ratio of 1:2 and 1:2.35 was obtained, respectively. In retraction with tip movement, the apical one third of the root tipped labially reducing the superior area of labial maxillaris by 19%. However, due to the compensating effect of the retraction movement, no apex approximation to the labial cortical plate occurred (eliminating the hazard of root resorption, dehiscence, or fenestration). In retraction with torque movement, the increase in both superior (28%) and inferior (65%) labial maxillaris areas was indicative for the hazard of root approximation to the palatal cortical bone. It is recommended to use the 1:2 bone remodeling/tooth movement ratio as a guideline to determine the biocompatible range of orthodontic tooth movements. Furthermore, a judicious interplay between the two modes of retraction can prevent major biologic impairments associated with the ratio and can extend the orthodontic range of treatment.

Bone Remodeling↗