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A six-year follow-up study of sports-related dental injuries in children and adolescents.

The records were analyzed of 106 patients with sports-related dental traumas treated in 1983 at the public oral surgery unit in Helsinki, Finland; 51 were examined six years after injury. The mean age was 11.8 years (range 7-24 years). The woman/man ratio was 1:3. In 39% of cases, the injuries had arisen from ice hockey or skating; 30% happened during school hours; 80% were uncomplicated crown fractures, concussions or subluxations. During the six-year follow-up, of 80 teeth in 51 patients, root resorption was found in 6 teeth (7.5%), periapical lesions were noted in 2 teeth (2.5%), and obliteration of the pulp was seen in 4 teeth (5%). Three teeth (3.7%) had suffered loss of vitality. The pulp had been extirpated in 13 of the traumatized teeth (16%). In all, 13.7% of the patients were found to have complications six years later. The results showed that long follow-up periods are needed after dental injury.

Adolescent↗

Periodontal ligament vitality and histologic healing of teeth stored for extended periods before transplantation.

A previous study evaluated the viability of dog periodontal ligament cells as indicated by tritiated thymidine uptake after extended storage in Hank's balanced salt solution and Conditioned Medium. The purpose of this study was to evaluate histologic healing following the identical storage parameters established in the earlier study. Additionally, for Conditioned Medium, matched pairs (teeth evaluated for tritiated thymidine uptake and transplanted teeth) were examined in an attempt to correlate periodontal ligament vitality and healing. Forty-six extracted endodontically treated dogs' teeth were randomly grouped and stored in Hank's balanced salt solution or Conditioned Medium for 6, 48, and 96 h and then transplanted into 6-, 48-, and 96-h sockets. The control group teeth were transplanted without storage into 6-, 48-, or 96-h sockets. After 6 months the dogs were killed and the teeth were prepared for histologic evaluation according to Andreasen. Complete healing, inflammatory root resorption, and replacement resorption were evaluated and compared. Overall, significantly better healing was observed for teeth stored in Conditioned Medium than for teeth stored in Hank's balanced salt solution. Conditioned Medium was not significantly different from controls. Additionally, there was a positive correlation between periodontal ligament viability and healing for Conditioned Medium. These results confirmed the importance of periodontal ligament viability in successful replantation and the potential of Conditioned Medium as a storage medium for avulsed teeth.

Animals↗

Cytotoxicity evaluation of sodium alendronate on cultured human periodontal ligament fibroblasts.

External root resorption processes are usually associated with dental trauma, mainly avulsion and intrusion. In such cases endodontic therapy aims to prevent this process by using medications that can inhibit osteoclastic activity, such as bisphosphonates. However, these drugs must be biocompatible to the periapical tissues. The aim of this study was to analyze the cytotoxicity of a bisphosphonate (sodium alendronate) on human periodontal ligament fibroblasts (PDL cells). Cells were plated in a density of 1 x 10(3) cells per dish. The experimental groups were GI (control) no sodium alendronate, and GII, GIII, and GIV with sodium alendronate at the concentrations of 10(-5), 10(-6), and 10(-7) M, respectively. The experimental times were 1, 6, 12, and 24 h (short-term) for viability and 2, 4, 6, and 8 days (long-term) for cell survival. Data in triplicate were statistically analyzed. Cultures treated with the highest alendronate concentration (GII) showed cell viability percentages significantly lower (P < 0.01) than those of the other groups (GI, GIII, and GIV), at 12 and 24 h. Cell growth on GII and GIII groups was similar. GII presented smaller growth than the other groups (P < 0.05). We concluded that sodium alendronate, on direct contact with human periodontal ligament fibroblasts, is cytotoxic in concentrations higher than of 10(-6) M.

Alendronate↗

Periodontal regeneration by FGF-2 (bFGF) in primate models.

We recently demonstrated that a topical application of basic fibroblast growth factor (FGF-2; bFGF) to alveolar bone defects in beagle dogs enhanced periodontal regeneration. The purpose of this study was further characterization of the biological effects of FGF-2 in non-human primates. Thirty-two inflamed furcation class II defects were surgically created in 4 male primates. The gelatinous carrier alone or the carrier containing 0.1 or 0.4% human recombinant FGF-2 was topically applied to the defects and compared with no treatment. Eight weeks after application, the periodontal regeneration in those defects was analyzed. In all FGF-2-treated sites, significant periodontal regeneration was dose-dependently observed in greater amounts than in the carrier-treated or non-treated sites. No instances of epithelial down-growth, ankylosis, or root resorption were observed in the FGF-2-treated sites. These results indicate that a topical application of FGF-2 can enhance considerable periodontal regeneration in surgically created furcation class II defects of non-human primates.

Alveolar Bone Loss↗

Bilateral maxillary periodontal ligament hamartoma in a dog.

A 12.5-year-old dog was presented for severe periodontal disease and bilateral maxillary enlargement. Radiographs of the maxilla showedgeneralized root resorption, ankylosis, and rarefaction of bone with focal radiodense areas. Surgical tooth extraction of multiple maxillary teeth and bilateral incisional biopsies of the periodontal tissue and maxilla in the region of the maxillary fourth premolars were performed. Histopathologic examination showed features typical of fully differentiated periodontal ligament with abundant cementum/alveolar lining bone and sparce odontogenic epithelial cell rests. Histopathology in conjunction with radiographic and clinical signs suggested a diagnosis of bilateral periodontal ligament hamartoma. Examination 3-months postoperatively indicated uncomplicated healing of the extraction and biopsy sites with no resolution of the maxillary enlargement.

Animals↗

Osteoclast differentiation.

The osteoclast is the primary bone resorbing cell. It is a highly specialized multinucleated cell whose primary function is to help in the control of calcium homeostasis. The osteoclast has been very difficult to study because of its relative inaccessability, low numbers, and fragility when isolated from bone. Recently, techniques have been developed to study the cell biology of the osteoclast that have expanded our ability to understand the biological and functional properties of osteoclasts. In this article, studies on the origin of the osteoclast are reviewed and the differentiation markers that are used to detect cells in the osteoclast lineage are discussed. Factors that affect osteoclast differentiation are presented and model systems currently in use for studying osteoclast differentiation are evaluated for their relative strengths and weaknesses. In addition, osteoclast differentiation during tooth eruption and root resorption and the effects of bone matrix elements on osteoclast differentiation are reviewed.

Cell Differentiation↗

Parathyroid-hormone-related protein induces expression of receptor activator of NF-{kappa}B ligand in human periodontal ligament cells via a cAMP/protein kinase A-independent pathway.

UNLABELLED: Periodontal ligament (PDL) cells play important roles in root resorption of human deciduous teeth by odontoclasts (osteoclast-like cells). However, it is unclear how PDL cells regulate osteoclastogenesis. We examined the effects of PTHrP, TGF-beta, and EGF, which are all secreted by the tooth germ, on tartrate-resistant acid-phosphatase-positive (TRAP+) cell formation using co-cultures of human PDL cells and mouse spleen cells. Only PTHrP promoted TRAP+ cell formation in co-cultures. PTHrP induced receptor activator of NF-kappaB ligand (RANKL) mRNA expression and slightly reduced osteoprotegerin (OPG) expression in PDL cells. The cAMP/PKA inhibitors Rp-cAMP, H89, and PKI did not affect PTHrP-induced TRAP+ cell formation. The PKC inhibitor, Ro-32-0432, suppressed RANKL expression in PDL cells and PTHrP-induced TRAP+ cell formation. However, this inhibitor directly modulated the number of osteoclast precursors. Thus, PTHrP induces osteoclastogenesis by increasing the relative expression level of RANKL vs. OPG in PDL cells via a cAMP/PKA-independent pathway. ABBREVIATIONS: PTHrP, parathyroid-hormone-related protein; TGF-beta, transforming growth factor-beta; EGF, epidermal growth factor; RANKL, receptor activator of NF-kappaB ligand; OPG, osteoprotegerin; PDL, periodontal ligament; TRAP, tartrate-resistant acid phosphatase; PKA, protein kinase A; PKC, protein kinase C; MAP, mitogen-activated protein; ERK, extracellular signal-regulated kinase; cAMP, cyclic Adenosine 3'5'-Monophosphate.

Acid Phosphatase↗

Osteoclastogenic activity during mandibular distraction osteogenesis.

Mandibular distraction osteogenesis is a well-developed clinical modality for the treatment of craniofacial deformities and dental arch discrepancies, in combination with orthodontic treatment. However, in our previous study, orthodontic tooth movement into the distraction gap caused severe root resorption. The present study aimed to clarify the osteoclastogenic activity of cells in the distraction gap. We hypothesized that the gene expression of osteoclastogenic- and osteoclast-supporting molecules in osteoblasts and stromal cells would increase at distraction sites during the consolidation period. An animal model experiment involving rabbits was designed for mandibular distraction osteogenesis and subjected to in situ hybridization analysis. The number of osteoclasts was larger in the distraction gap during the early consolidation period than in normal controls, due to an increase of gene expression for osteoclastogenic cytokines in osteoblasts. It was concluded that osteoclastogenic and osteoclastic activities are stimulated at distraction sites during the early consolidation period.

Animals↗

Judgement on removal of asymptomatic mandibular third molars: influence of the perceived likelihood of pathology.

Thirty general dental practitioners and 10 oral surgeons were asked to judge the need for removal of 36 asymptomatic impacted third molars. To estimate the reliability of the judgement, the 36 cases were duplicated. The participants had to estimate the strength of the indication for extraction and, if the teeth were not extracted, the probability of development of pathology in general and of six specific complications on a Visual Analogue Scale. Multiple linear regression analysis was used to describe their judgement. There was a high correlation between the indication index for extraction and the perceived likelihood of the development of pathology, although there was considerable individual variation. The general dental practitioners rated cyst development as the most, and pericoronitis as the second most, influential factors in their decision to extract the third molar. The oral surgeons rated pericoronitis the highest and the development of a cyst or caries in the second molar as the second highest factors influencing their judgement. Tumour formation and root resorption received low weightings. Intraexaminer reliability was high. The study confirms that the judgement to extract asymptomatic impacted third molars is not made solely on the basis of cognitive factors.

Adult↗

Radiological features of glandular odontogenic cyst.

OBJECTIVES: To present five new cases of glandular odontogenic cyst (GOC) and to review the radiological features at presentation as reported in the English literature. METHODS: From 1993 to 2002, five patients in our department were diagnosed with GOC based on histopathological findings and supported by radiography and CT. The radiographic features of the new GOC cases were analysed in addition to 51 literature cases. RESULTS: There were 31 male and 25 female patients, aged 14-90 years (mean 50 years). The mandible was involved in 80% and the maxilla in 20%; most of the lesions were located in the anterior jaw. Radiographically, 52% of the lesions were unilocular and 48% were multilocular; 94.5% showed well defined borders, which were sclerotic in 7.7% and scalloped in 13%. Information on cortical plate integrity was available in only 24 cases: 50% showed perforation, 8.3% erosion of the cortical plates and 8.3% thinning of the cortical plates. Root resorption was reported in 22% of patients and tooth displacement in 24.4%. CONCLUSIONS: Data collected indicate that GOC has potentially aggressive behaviour, with expansion and perforation in a significant number of cases. We recommend the use of multiple plane radiographs, with CT reserved for large lesions, especially those that are multilocular or involve extragnathic structures.

Adolescent↗

Ameloblastoma in the Hong Kong Chinese. Part 2: systematic review and radiological presentation.

OBJECTIVES: The aim of this part of the study was to determine the radiological presentation on conventional radiographs of central ameloblastomas in the Hong Kong Chinese and compare them with other reported series by a systematic review (SR). METHODS: The study had two elements, that of a complete series of all ameloblastomas presenting at a major Chinese maxillofacial surgical unit and a SR. The files of the Department of Oral and Maxillofacial Surgery of the University of Hong Kong between 1989 and 2000 were reviewed for ameloblastoma cases. The relevant literature was identified by electronic databases, review of citation lists and handsearching of key journals. The principal selection criterion was that the study should represent a complete collection of cases. RESULTS: Only 13 reports gave any radiological details. The present study of the Hong Kong Chinese contained 61 cases. With the exception of radiodensity and shape of radiolucency, the majority of the 13 other reports did not record the other radiological features that could be important in the diagnosis. The present study agreed with the synthesis of the 13 reports with regards to complete radiolucency and cortication of ameloblastomas, but disagreed with regards to other important features. The present study had a significantly higher proportion of unilocular lesions, better marginal definition, and more frequent perforation of the cortex and buccolingual expansion. Nine of the ten maxillary lesions straddled both anterior and posterior sextants with four crossing the midline, whereas only 13 of the 51 mandibular cases affected both sextants, of which eight crossed the midline. The unicystic form, which was most prevalent, appeared significantly more frequently as unilocular radiolucencies in comparison with the non-unicystic forms. The frequencies of unicystic forms and unilocular presentations were significantly greater in the young. The lesions in the young were significantly sited solely in the posterior sextant. The lower border of the mandible was reached and affected by ameloblastoma in 36 cases in the present report. It was displaced and thinned in 15 cases whereas in just five it was at least partially undisplaced with the lesion expanding down past it either buccally or lingually to it. The unicystic form was significantly more associated with root resorption, tooth displacement and crowns of unerupted teeth. CONCLUSIONS: Radiologically, ameloblastomas in the Hong Kong Chinese differ significantly with regards to many features. This can be in part explained by the higher proportion of the unicystic form.

Age Factors↗

Clinical and radiological features of odontogenic ghost cell carcinoma: review of the literature and report of four new cases.

OBJECTIVES: To analyse systematically the clinical and radiological features of odontogenic ghost cell carcinoma (OGCC). METHODS: Clinical and radiological features of 22 OGCCs (4 new and 18 from the literature) were analysed. RESULTS: There were 17 (77%) males and 5 (23%) females (male-to-female ratio of 3.4:1). Ages ranged from 13 years to 72 years (mean 36.7) with a peak in the fourth (40.9%) and fifth (27.3%) decades. The maxilla was involved in 68% and the mandible in 32%. Our study confirmed that OGCC is more prevalent in Asians (12/18) than in other racial groups. The mixed radiolucent and radiopaque lesion pattern was the most frequent (14/19) compared with radiolucent lesions (5/19). 89% (17/19) showed poorly defined borders and 11% (2/19) showed well defined borders. Root resorption was reported in 31% (6/19) of patients and tooth displacements in 21%. CONCLUSIONS: OGCC demonstrates clinical and radiographic features of a malignant tumour with high recurrence.

Adult↗

Pulpectomy procedure for deciduous teeth with severe pulpal necrosis.

Pulpectomies of deciduous teeth with severe pulpal necrosis should be considered as a possible treatment plan. Systemic and dental criteria have been devised to help the clinician to select cases in which successful results may be produced. A clinical success occurs when the pulpectomized tooth is painless, is firm in its alveolar socket, and is without a fistulous tract. Radiographically, any radiolucent area should be resolving with six months, and no pathologic root resorption should be observed. Research should determine whether pulpectomies may be done on children with severe systemic disease and should determine long-term consequences of underfilled and overfilled pulpectomies.

Dental Pulp Capping↗

Replantation of a mandibular molar: report of case.

A patient with an alveolar abscess, swelling, pain, and an extremely mobile tooth had had previous root canal treatment. Extraction was recommended but, with informed consent and the patient's desire to keep his tooth, intentional replantation was performed as a last resort. Matsura's method of canal preparation, which results in a large area of amalgam on the root surface, was used. This method did not impair healing. According to Bjorvatn and Massler, 11 application of 1% SNF2 to the root surfaces for five minutes reduces root resorption. This technique was not used in this case. Clinical and radiographic observation for almost four years substantiate this as a successful case.

Adult↗

The use of temporary anchorage devices for molar intrusion.

BACKGROUND: This article reviews the use of temporary anchorage devices (TADs) for maxillary molar intrusion. TYPES OF STUDIES REVIEWED: The authors reviewed clinical, radiographic and histologic studies and case reports. The studies provided information regarding the application, placement and biological response of orthodontic TADs. RESULTS: TAD-supported molar intrusion is controlled and timely and may be accomplished without the need for full-arch brackets and wires. Supraerupted maxillary first molars can be intruded 3 to 8 millimeters in 7.5 months (approximately 0.5-1.0 mm per month), without loss of tooth vitality, adverse periodontal response or radiographically evident root resorption. CLINICAL IMPLICATIONS: True molar intrusion can be achieved successfully with orthodontic TADs, re-establishing a functional posterior occlusion and reducing the need for prosthetic crown reduction.

Humans↗

[Experimental model of tooth mobility in the human "in vivo"].

The aim of the present study was to investigate experimentally the mechanical properties of tooth deflection under external loading. These properties have a significant impact on tooth movement during orthodontic treatment. The stresses and strains caused by tooth movement influence bone remodelling, which is the basis of orthodontic treatment. The movement of a tooth as a direct reaction to the forces acting on it is termed "initial" movement. It is nonlinear and has a clearly time-dependent component. While the initial tooth movement represents the totality of the reaction mechanisms of all the tissues of the tooth unit, it is determined primarily by the mechanical properties of the periodontal ligament (PDL). The PDL is the softest tissue of the tooth unit and is therefore subject to the largest deformations when forces act on the crown of the tooth. The objective of orthodontic treatment is to achieve as precise and rapid tooth movement as possible, without provoking such undesired effects as bone and root resorption. To enable the implementation of an optimal orthodontic force system that meets these requirements, a thorough knowledge of the biomechanics of tooth movement is a must.

Biomechanical Phenomena↗

Experimental tooth movement into bone induced by recombinant human bone morphogenetic protein-2.

OBJECTIVE: The development of biomaterials for secondary bone grafting to the alveolar cleft, recombinant human morphogenetic protein-2 (rhBMP-2) may have great potential to promote osseous regeneration. The purpose of this study was to investigate the osteoinductive activity of low-dose rhBMP-2 (10 microg/100 microL) and the biological response of newly generated bone to orthodontic stimulation, compared with previous results using high-dose rhBMP-2 (40 microg/100 microL). METHOD: After extraction of the maxillary first premolars, bone defects were surgically created in eight adult beagle dogs using a 5-mm-diameter trepan bar. The rhBMP-2 with a PLGA/gelatin sponge complex (PGS) made of gelatin and polylactic acid polyglycolic acid copolymer was immediately implanted. The osteoinductive activity of rhBMP-2 and tooth movement into the newly generated bone was evaluated based on histological and morphometric examination. RESULTS: Dramatic histological and morphometric differences were found in the time course of bone remodeling between low- and high-dose rhBMP-2. The onset of bone remodeling occurred significantly earlier in low-dose rhBMP-2. During experimental tooth movement, in contrast to high-dose rhBMP-2, with which root resorption occurred, only partial cementum resorption occurred on the pressure side with low-dose rhBMP-2. CONCLUSION: These results indicated that the proper dosage of rhBMP-2 should be determined for successful clinical application.

Absorbable Implants↗