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PubMed1988

Allotransplantation and autotransplantation of mature teeth in monkeys: the influence of endodontic treatment.

This study investigated the effect of endodontic treatment on root resorption of autotransplanted and allotransplanted mature teeth in unmatched monkeys. The material comprised 40 mature maxillary central incisors in 20 green Vervet monkeys (Cercopithecus aethiops). Teeth were either allotransplanted or autotransplanted in pairs of monkeys matched only for the size of the root. Endodontic treatment was performed at random peroperatively with gutta percha and Kerr sealer in 10 of each of the 20 autografts and 20 allografts. The extra-alveolar period was 18 minutes in all groups. Histometric analysis, which included registration of surface and inflammatory and replacement resorption (ankylosis), was done on serial sections of the grafts 8 weeks after transplantation. Endodontic treatment almost completely reduced inflammatory resorption in both allotransplanted and autotransplanted mature teeth (p less than 0.01). Peroperative endodontics elicited a small increase in ankylosis in autografts. In allografts, it unmasked a high amount of ankylosis, presumably primarily due to alloimmune reactions against the donor periodontal ligament, leaving only a small portion of normal ligament almost exclusively located along the cervical region of the root surface. Downgrowth of periodontal pocket epithelium was limited in all groups.

Animals↗
PubMed1991

The central (intraosseous) calcifying odontogenic cyst: an analysis of 215 cases.

This study reviews and analyzes the clinical, radiographic, and histomorphologic features of the 215 cases of central calcifying odontogenic cyst (CCOC) reported in the literature. Based on the present information, a clinicopathologic classification of calcifying odontogenic cyst is proposed. The CCOC is also compared with its peripheral counterpart and the differences discussed.

Adolescent↗
PubMed1988

Effect of orthodontic force on periodontal tissue metabolism. A histologic and biochemical study in normal and hypocalcemic young rats.

The relationship between force and degradation activity after application of orthodontic force is still obscure. Of particular clinical interest are the etiologic factors behind excessive root resorptions appearing in connection with orthodontic movement of teeth that has been proposed to be influenced by systemic factors regulating the tissue-degrading activity in periodontal tissues. Thus, the aim was, by histologic and new biochemical methods, to investigate the effect of orthodontic forces on the periodontal tissues in the normal and the hypocalcemic situation with secondary hyperparathyroidism. Root resorptions were induced in upper incisors of normal and hypocalcemic rats by subjecting the teeth to a moderate orthodontic force. In both groups the resorption of the roots occurred consistently in the vicinity of reorganizing areas of the periodontal ligament (PDL) with ongoing degradative activities and alveolar bone resorption. Furthermore, specific cell metabolic changes in alveolar bone and PDL in tension and pressure zones were detected and quantified by biochemical determination of alkaline phosphatase activity. This biochemical quantification of the metabolic changes together with the morphologic observations gave the clinically valuable information that the observed increase in occurrence and severity of root resorptions in moderate hypocalcemia was related to an increase in alveolar bone turnover. This study has shown that root resorptions were clearly related to the degradation process occurring in the vicinity of the hyaline zone and that in the hypocalcemic situation, the increase in root resorptions was related to an enhanced alveolar bone resorption. Thus, factors that minimize the time for resorptive/degradative activity should be discussed in this context rather than force per se.

Alkaline Phosphatase↗
PubMed1989

Labial root torque: effect on the maxilla and incisor root apex.

This study was designed to determine the effectiveness of labial root torque on anterior nasomaxillary development. Quantification was made of the angular and linear changes in Downs' point A (representing midsagittal basal bone) and incisor point A (representing the dentoalveolar bone) and any concomitant incisor root resorption. The study was divided into two parts: part 1--to determine the anatomic configuration of the premaxillary region by use of laminagraphy on skulls, and part 2--to use the morphologic landmarks found in part 1 to assess the development of the nasomaxillary complex in maxillary retrusive patients. The clinical study involved 17 maxillary retrusive patients, aged 8.0 to 15.7 years, who had been treated for a period between 0.31 and 3.70 years with edgewise advancing mechanics. Clinical results indicate that during the first phase of orthodontic treatment with labial root torque, encompassing a 0.63-year mean treatment period, a greater rate of advancement of Downs' point A was produced when compared with normal growth. The skeletal convexity increased, whereas normal growth straightened the profile. Incisor point A advanced at a greater rate than Downs' point A, suggesting that treatment caused a larger dentoalveolar effect than the effect on midsagittal basal bone. When treatment was extended to 1.57 years, similar changes were found but at a reduced rate. Overall apical root resorption was 12.7%/year. Sex and age were not found to have any correlation to the amount of apical root loss.

Cephalometry↗
PubMed1989

A study of the relationship between incisor intrusion and root shortening.

Apical root shortening is one of the most common complications of orthodontic treatment. Force magnitude has been suggested as an important factor. Studies on the occurrence of root resorption show equivocal results. The aim of the present study was to evaluate the relationship between intrusion with low forces (25 gm) using utility arches in the bioprogressive technique and root shortening. Age, sex, facial type, treatment time, extraction versus nonextraction therapy, width of the symphysis, and the angle of the incisors to skeletal reference planes also were studied for their relationship to intrusion and root shortening. Root shortening was found to average 1.84 mm for maxillary incisors and 0.61 mm for mandibular incisors subjected to intrusive force. Intrusion of incisors in a population exhibiting growth was found to be one of "holding against growth" and in the upper arch to a change in angulation of the maxillary incisors. Furthermore, when extraction was a part of the orthodontic treatment, it was related to intrusion of maxillary incisors but not to intrusion of mandibular incisors. No relationship was found between the amount of root shortening and degree of intrusion achieved. However, a long treatment time was significantly correlated to root shortening. None of the other characteristics studied were related to either intrusion or root shortening. In the present study, it was found that intrusion with the utility arch type of technique is not related to amount of root shortening. The degree of root shortening was markedly higher in the maxilla than the mandible. In general, treatment time was the most significant factor for occurrence of root shortening.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed2004

Root resorption in human mandibular first premolars after rotation as detected by scanning electron microscopy.

The aims of this study were to investigate the presence, location, and severity of root resorption after orthodontic rotation for different lengths of time. Eighteen mandibular first premolars due to be extracted from 9 patients were intraindividually divided into 2 groups. Eight teeth were not moved (control group), and 10 teeth were rotated (experimental group) with a force of 50 g delivered by elastomeric modules through symmetrical brackets bonded on the buccal and lingual surfaces (25 g buccally and 25 g lingually) for periods of 2, 3, 4, and 6 weeks. The teeth were extracted, fixed, and treated with 2% sodium hypochlorite to remove the organic tissue components and then dehydrated in ethanol, air-dried, coated with gold, and analyzed in a scanning electron microscope. Examination by scanning electron microscopy revealed many concavities (resorption lacunae) on the root surfaces of all rotated teeth. The resorption areas were located mainly at the medial root third, in regions that corresponded to the prominent zones of the roots. The resorption lacunae in the teeth moved for longer time periods were deeper, often affecting the underlying root dentin, and were mainly at the medial root third. Both the apical and cervical thirds were clearly less affected at all the studied intervals. The root surfaces at the nonprominent root zones did not show signs of resorption.

Adolescent↗
PubMed2005

Physical properties of root cementum: Part 5. Volumetric analysis of root resorption craters after application of light and heavy orthodontic forces.

BACKGROUND: In previous studies on root resorption, resorption was quantified by making histologic cuts or by surface area measurements of resorption craters. The aims of this study were to evaluate the effects of orthodontic force magnitude on root resorption craters with volumetric measurements and also to identify the sites that might be predisposed to resorption. METHODS: After an experimental time of 28 days, 36 human premolars previously divided into light-force (25 g) and heavy-force (225 g) groups were extracted and prepared for scanning electron microscope imaging. Pairs of stereo images were taken, and 3-dimensional quantitative volumetric analysis was performed with commercial software. RESULTS AND CONCLUSIONS: The mean volume of the resorption crater in the light-force group was 3.49-fold greater than in the control group; the mean volume of the resorption crater in the heavy-force group was 11.59-fold greater than in the control group ( P < .001). The heavy-force group had 3.31-fold greater total resorption volume than the light-force group ( P < .001). Buccal cervical and lingual apical regions had significantly more resorption craters than the other regions ( P < .001). There was more resorption by volume in the heavy-force group compared with the light-force group and controls. Although more resorption was recorded in the light-force group, the difference in the amount of resorption between the light-force and control groups was not statistically significant. There was significantly more resorption on the buccal cervical and lingual apical regions of the root surfaces than on the other regions, suggesting that high-pressure zones might be more susceptible to resorption after 28 days of force application.

Adolescent↗
PubMed2005

Can the severity of root resorption be accurately judged by means of radiographs? A case report with histology.

INTRODUCTION: Root resorption of lateral incisors caused by the pressure of erupting canines is a well-known but relatively rare problem in orthodontics and general dentistry. It is usually diagnosed on radiographs. The purpose of this article is to discuss some difficulties associated with evaluating root resorption from radiographs alone. A case report is presented as an example. METHODS: Radiographs showed that an 11-year-old girl had marked root resorption of the maxillary lateral incisors, caused by the impacted permanent canines. The incisors were to be extracted. Several months before the extractions, a canine had been surgically exposed to remove pressure from the incisor root. The lateral incisors were analyzed histologically, and the histologic findings were compared with those of the patient's mandibular first premolars, which had been extracted. RESULTS: The resorption of the lateral incisors was more severe than expected from the radiographs. The resorption extended far into the pulp. Most, although not all, root resorption areas showed histologic evidence of repair, but the amount of repair was far from functional repair levels. The mandibular first premolars had no signs of resorption, thus excluding systemic causes. CONCLUSIONS: The severity of root resorption of lateral incisors cannot be accurately judged from radiographs alone.

Bicuspid↗
PubMed2004

Are breeding teeth in Atlantic salmon a component of the drastic alterations of the oral facial skeleton?

Upriver spawning migration of starving Atlantic salmon (Salmo salar) involves drastic skeletal alterations, among which a toothless stage followed by the appearance of a new set of so-called breeding teeth has been described. To investigate this phenomenon, we examined the patterns of tooth replacement on the lower jaws in different life stages of wild animals before and after spawning. Prior to spawning, every position held either a functional or a replacement tooth, both in first-time (grilse) and repetitive (salmon) spawners. Teeth were in a similar developmental stage every three positions along the tooth row. A functional tooth occurred in every third position and intermediate positions were taken by developing teeth. Within the process of replacement, teeth were resorbed and not shed. Our observations on an uninterrupted tooth replacement pattern provided no evidence of an intermediate toothless stage nor of a specialized breeding-teeth generation. Only animals that survived spawning (kelts) showed a highly variable tooth pattern, but with the initial "every third position" pattern still recognizable in some animals. We hypothesise that previous accounts describing a complete tooth loss/replacement relate to proliferation of the oral mucosa that conceals the teeth prior to the breeding period and to the use of maceration techniques that could have removed all teeth with an incompletely mineralised base.

Animals↗
PubMed2006

Amelogenin is a negative regulator of osteoclastogenesis via downregulation of RANKL, M-CSF and fibronectin expression in osteoblasts.

Amelogenin is a novel enamel matrix protein. Knockout mice showed enhanced osteoclast formation and resorption of tooth cementum. This study investigated the effects of amelogenin on osteoclastogenesis. In co-cultures with calvaria osteoblasts and purified bone marrow cells, amelogenin inhibited osteoclastogenesis dramatically. Furthermore, amelogenin inhibited the expression of receptor activator of nuclear factor kappaB ligand (RANKL), macrophage-colony stimulating factor (M-CSF) and fibronectin in osteoblasts, while RANKL expression was induced by fibronectin and inhibited by treatment with fibronectin small interfering RNA. These results suggest that the inhibitory effects of amelogenin on osteoclastogenesis lead to downregulation of RANKL, M-CSF and fibronectin production in osteoblasts.

Amelogenin↗
PubMed2004

Autotransplantation of immature third molars into edentulous and atrophied jaw sections.

The aim of the present study was to assess the results after transplantation of 85 immature third molars. Recipient site conditions varied and different surgical techniques were used. The long-term results after preparation of a new alveolus, splitting osteotomy of the alveolar process or use of free bone autografts were compared with the results after transplantation into a fresh extraction site (control group). Transplantations into prepared sockets showed equal results to the control group (94% respectively). Transplantations in connection with free bone autografts (84%) or after splitting osteotomy of the alveolar process (63%) showed poorer success rates, the differences between the latter and the control group being statistically significant. A possible correlation to revascularization disturbances of the pulp due to an insufficiency of the recipient site or to postoperative infection is suspected. The results show that transplantation of immature third molars is a safe, useful procedure when appropriate conditions of the recipient site are present. Where the alveolus is atrophic, a splitting osteotomy should be performed only in exceptional cases and preference should be given to alternative methods such as primary bone augmentation or bone-regenerative procedures.

Adolescent↗
PubMed2005

Complications associated with segmentation of the maxilla: a retrospective radiographic follow up of 82 patients.

The aim of the present study was to retrospectively examine the clinical and radiographic incidence and frequency of injuries to teeth and their surrounding tissues adjacent to interdental osteotomies in conjunction with segmentation of the maxilla. Vertical interdental osteotomies have been performed in combination with Le Fort I osteotomy for correction of various dento-facial deformities. All our orthognathic patients are followed prospectively in a standardized manner. Eighty-two consecutive patients who underwent dento-facial correction by segmented maxillary osteotomy alone or in combination with simultaneous mandibular surgery between 1992 and 1998 were included in the study. They were followed for up to 30 months postoperatively. A total of 158 interdental osteotomies were performed, involving a total of 316 teeth. Only a small number of complications such as osteolytic processes, marginal bone destruction, root resorption or mechanical injuries to the teeth were seen.

Adult↗
PubMed2005

Bone loss and teeth.

Loss of teeth results in irreversible alveolar bone resorption, and untreated dental disease causes alveolar bone lysis that ultimately leads to loss of teeth. In addition to anchoring the teeth in the alveolar ridge, the maxillary and mandibular bone allows dental restoration procedures, such as construction of root-supported implants, fixed dentures, or removable dentures. However, the functional and cosmetic results depend on the quantity and quality of the maxillary or mandibular bone, which can be affected by many normal and abnormal processes. The alveoli are particularly fragile and labile. Changes in alveolar bone vary considerably across individuals and depend directly on local factors. Many studies have investigated associations between alveolar bone status and bone mass at other skeletal sites. These studies focused chiefly on the course of parodontal disease, alveolar ridge resorption after tooth extraction, and density differences across various mandibular sites. They produced conflicting results, probably because of differences in measurement methods. Measurement sites and methods should be standardized to ensure that reliable and comparable data are obtained. To date, there are few reliable methods for obtaining quantitative measurements of bone mineral content in maxillary and mandibular bone.

Bone Density↗