Root Resorption: Resorption in which cementum or dentin is lost from the root of a tooth owing to cementoclastic or osteoclastic activity in conditions such as trauma of occlusion or neoplasms. (Dorland, 27th ed)Bone Resorption: Bone loss due to osteoclastic activity.Tooth Movement: Orthodontic techniques used to correct the malposition of a single tooth.Tooth Root: The part of a tooth from the neck to the apex, embedded in the alveolar process and covered with cementum. A root may be single or divided into several branches, usually identified by their relative position, e.g., lingual root or buccal root. Single-rooted teeth include mandibular first and second premolars and the maxillary second premolar teeth. The maxillary first premolar has two roots in most cases. Maxillary molars have three roots. (Jablonski, Dictionary of Dentistry, 1992, p690)Tooth Apex: The tip or terminal end of the root of a tooth. (Jablonski, Dictionary of Dentistry, 1992, p62)Incisor: Any of the eight frontal teeth (four maxillary and four mandibular) having a sharp incisal edge for cutting food and a single root, which occurs in man both as a deciduous and a permanent tooth. (Jablonski, Dictionary of Dentistry, 1992, p820)Tooth Exfoliation: Physiologic loss of the primary dentition. (Zwemer, Boucher's Clinical Dental Terminology, 4th ed)Dental Cementum: The bonelike rigid connective tissue covering the root of a tooth from the cementoenamel junction to the apex and lining the apex of the root canal, also assisting in tooth support by serving as attachment structures for the periodontal ligament. (Jablonski, Dictionary of Dentistry, 1992)Orthodontics, Corrective: The phase of orthodontics concerned with the correction of malocclusion with proper appliances and prevention of its sequelae (Jablonski's Illus. Dictionary of Dentistry).Bicuspid: One of the eight permanent teeth, two on either side in each jaw, between the canines (CUSPID) and the molars (MOLAR), serving for grinding and crushing food. The upper have two cusps (bicuspid) but the lower have one to three. (Jablonski, Dictionary of Dentistry, 1992, p822)Maxilla: One of a pair of irregularly shaped bones that form the upper jaw. A maxillary bone provides tooth sockets for the superior teeth, forms part of the ORBIT, and contains the MAXILLARY SINUS.Orthodontic Appliances: Devices used for influencing tooth position. Orthodontic appliances may be classified as fixed or removable, active or retaining, and intraoral or extraoral. (Boucher's Clinical Dental Terminology, 4th ed, p19)Molar: The most posterior teeth on either side of the jaw, totaling eight in the deciduous dentition (2 on each side, upper and lower), and usually 12 in the permanent dentition (three on each side, upper and lower). They are grinding teeth, having large crowns and broad chewing surfaces. (Jablonski, Dictionary of Dentistry, 1992, p821)Tooth Resorption: Resorption of calcified dental tissue, involving demineralization due to reversal of the cation exchange and lacunar resorption by osteoclasts. There are two types: external (as a result of tooth pathology) and internal (apparently initiated by a peculiar inflammatory hyperplasia of the pulp). (From Jablonski, Dictionary of Dentistry, 1992, p676)Tooth, Deciduous: The teeth of the first dentition, which are shed and replaced by the permanent teeth.Cuspid: The third tooth to the left and to the right of the midline of either jaw, situated between the second INCISOR and the premolar teeth (BICUSPID). (Jablonski, Dictionary of Dentistry, 1992, p817)Orthodontic Wires: Wires of various dimensions and grades made of stainless steel or precious metal. They are used in orthodontic treatment.Tooth Replantation: Reinsertion of a tooth into the alveolus from which it was removed or otherwise lost.Tooth Cervix: The constricted part of the tooth at the junction of the crown and root or roots. It is often referred to as the cementoenamel junction (CEJ), the line at which the cementum covering the root of a tooth and the enamel of the tooth meet. (Jablonski, Dictionary of Dentistry, 1992, p530, p433)Radiography, Panoramic: Extraoral body-section radiography depicting an entire maxilla, or both maxilla and mandible, on a single film.Osteoclasts: A large multinuclear cell associated with the BONE RESORPTION. An odontoclast, also called cementoclast, is cytomorphologically the same as an osteoclast and is involved in CEMENTUM resorption.Tooth Eruption, Ectopic: An abnormality in the direction of a TOOTH ERUPTION.Tooth Mobility: Horizontal and, to a lesser degree, axial movement of a tooth in response to normal forces, as in occlusion. It refers also to the movability of a tooth resulting from loss of all or a portion of its attachment and supportive apparatus, as seen in periodontitis, occlusal trauma, and periodontosis. (From Jablonski, Dictionary of Dentistry, 1992, p507 & Boucher's Clinical Dental Terminology, 4th ed, p313)Periodontal Splints: Fixed or removable devices that join teeth together. They are used to repair teeth that are mobile as a result of PERIODONTITIS.Alveolar Process: The thickest and spongiest part of the maxilla and mandible hollowed out into deep cavities for the teeth.Tooth Ankylosis: Solid fixation of a tooth resulting from fusion of the cementum and alveolar bone, with obliteration of the periodontal ligament. It is uncommon in the deciduous dentition and very rare in permanent teeth. (Jablonski's Dictionary of Dentistry, 1992)Nail Biting: Common form of habitual body manipulation which is an expression of tension.Serial Extraction: The selective extraction of deciduous teeth during the stage of mixed dentition in accordance with the shedding and eruption of the teeth. It is done over an extended period to allow autonomous adjustment to relieve crowding of the dental arches during the eruption of the lateral incisors, canines, and premolars, eventually involving the extraction of the first premolar teeth. (Dorland, 28th ed)Periodontal Ligament: The fibrous CONNECTIVE TISSUE surrounding the TOOTH ROOT, separating it from and attaching it to the alveolar bone (ALVEOLAR PROCESS).Tooth, Impacted: A tooth that is prevented from erupting by a physical barrier, usually other teeth. Impaction may also result from orientation of the tooth in an other than vertical position in the periodontal structures.Gingival Crevicular Fluid: A fluid occurring in minute amounts in the gingival crevice, believed by some authorities to be an inflammatory exudate and by others to cleanse material from the crevice, containing sticky plasma proteins which improve adhesions of the epithelial attachment, have antimicrobial properties, and exert antibody activity. (From Jablonski, Illustrated Dictionary of Dentistry, 1982)Tooth Extraction: The surgical removal of a tooth. (Dorland, 28th ed)Fetal Resorption: The disintegration and assimilation of the dead FETUS in the UTERUS at any stage after the completion of organogenesis which, in humans, is after the 9th week of GESTATION. It does not include embryo resorption (see EMBRYO LOSS).Dentition, Permanent: The 32 teeth of adulthood that either replace or are added to the complement of deciduous teeth. (Boucher's Clinical Dental Terminology, 4th ed)Tooth Abnormalities: Congenital absence of or defects in structures of the teeth.Tooth Injuries: Traumatic or other damage to teeth including fractures (TOOTH FRACTURES) or displacements (TOOTH LUXATION).Radiography, Dental, Digital: A rapid, low-dose, digital imaging system using a small intraoral sensor instead of radiographic film, an intensifying screen, and a charge-coupled device. It presents the possibility of reduced patient exposure and minimal distortion, although resolution and latitude are inferior to standard dental radiography. A receiver is placed in the mouth, routing signals to a computer which images the signals on a screen or in print. It includes digitizing from x-ray film or any other detector. (From MEDLINE abstracts; personal communication from Dr. Charles Berthold, NIDR)Periapical Granuloma: Chronic nonsuppurative inflammation of periapical tissue resulting from irritation following pulp disease or endodontic treatment.Tooth, Unerupted: A normal developing tooth which has not yet perforated the oral mucosa or one that fails to erupt in the normal sequence or time interval expected for the type of tooth in a given gender, age, or population group.Dental Fistula: An abnormal passage in the oral cavity on the gingiva.Periapical Tissue: Tissue surrounding the apex of a tooth, including the apical portion of the periodontal membrane and alveolar bone.Root Canal Therapy: A treatment modality in endodontics concerned with the therapy of diseases of the dental pulp. For preparatory procedures, ROOT CANAL PREPARATION is available.RANK Ligand: A transmembrane protein belonging to the tumor necrosis factor superfamily that specifically binds RECEPTOR ACTIVATOR OF NUCLEAR FACTOR-KAPPA B and OSTEOPROTEGERIN. It plays an important role in regulating OSTEOCLAST differentiation and activation.Tooth Avulsion: Partial or complete displacement of a tooth from its alveolar support. It is commonly the result of trauma. (From Boucher's Clinical Dental Terminology, 4th ed, p312)Cone-Beam Computed Tomography: Computed tomography modalities which use a cone or pyramid-shaped beam of radiation.Dentin: The hard portion of the tooth surrounding the pulp, covered by enamel on the crown and cementum on the root, which is harder and denser than bone but softer than enamel, and is thus readily abraded when left unprotected. (From Jablonski, Dictionary of Dentistry, 1992)Anodontia: Congenital absence of the teeth; it may involve all (total anodontia) or only some of the teeth (partial anodontia, hypodontia), and both the deciduous and the permanent dentition, or only teeth of the permanent dentition. (Dorland, 27th ed)Pulpectomy: Dental procedure in which the entire pulp chamber is removed from the crown and roots of a tooth.Denture, Partial, Temporary: A partial denture intended for short-term use in a temporary or emergency situation.Radiography, Dental: Radiographic techniques used in dentistry.Acid Phosphatase: An enzyme that catalyzes the conversion of an orthophosphoric monoester and water to an alcohol and orthophosphate. EC Bone Loss: Resorption or wasting of the tooth-supporting bone (ALVEOLAR PROCESS) in the MAXILLA or MANDIBLE.Malocclusion, Angle Class I: Malocclusion in which the mandible and maxilla are anteroposteriorly normal as reflected by the relationship of the first permanent molar (i.e., in neutroclusion), but in which individual teeth are abnormally related to each other.Overbite: A malocclusion in which maxillary incisor and canine teeth project over the mandiblar teeth excessively. The overlap is measured perpendicular to the occlusal plane and is also called vertical overlap. When the overlap is measured parallel to the occlusal plane it is referred to as overjet.Tooth Attrition: The wearing away of a tooth as a result of tooth-to-tooth contact, as in mastication, occurring only on the occlusal, incisal, and proximal surfaces. It is chiefly associated with aging. It is differentiated from TOOTH ABRASION (the pathologic wearing away of the tooth substance by friction, as brushing, bruxism, clenching, and other mechanical causes) and from TOOTH EROSION (the loss of substance caused by chemical action without bacterial action). (Jablonski, Dictionary of Dentistry, 1992, p86)Tooth Crown: The upper part of the tooth, which joins the lower part of the tooth (TOOTH ROOT) at the cervix (TOOTH CERVIX) at a line called the cementoenamel junction. The entire surface of the crown is covered with enamel which is thicker at the extremity and becomes progressively thinner toward the cervix. (From Jablonski, Dictionary of Dentistry, 1992, p216)Epithelial Attachment: A wedge-shaped collar of epithelial cells which form the attachment of the gingiva to the tooth surface at the base of the gingival crevice.Alveolectomy: Subtotal or complete excision of the alveolar process of the maxilla or mandible. (Dorland, 28th ed)Osteoprotegerin: A secreted member of the TNF receptor superfamily that negatively regulates osteoclastogenesis. It is a soluble decoy receptor of RANK LIGAND that inhibits both CELL DIFFERENTIATION and function of OSTEOCLASTS by inhibiting the interaction between RANK LIGAND and RECEPTOR ACTIVATOR OF NUCLEAR FACTOR-KAPPA B.Root Canal Obturation: Phase of endodontic treatment in which a root canal system that has been cleaned is filled through use of special materials and techniques in order to prevent reinfection.Odontometry: Measurement of tooth characteristics.Cementogenesis: The formation of DENTAL CEMENTUM, a bone-like material that covers the root of the tooth.Bone and Bones: A specialized CONNECTIVE TISSUE that is the main constituent of the SKELETON. The principle cellular component of bone is comprised of OSTEOBLASTS; OSTEOCYTES; and OSTEOCLASTS, while FIBRILLAR COLLAGENS and hydroxyapatite crystals form the BONE MATRIX.Dental Sac: Dense fibrous layer formed from mesodermal tissue that surrounds the epithelial enamel organ. The cells eventually migrate to the external surface of the newly formed root dentin and give rise to the cementoblasts that deposit cementum on the developing root, fibroblasts of the developing periodontal ligament, and osteoblasts of the developing alveolar bone.Root Canal Filling Materials: Materials placed inside a root canal for the purpose of obturating or sealing it. The materials may be gutta-percha, silver cones, paste mixtures, or other substances. (Dorland, 28th ed, p631 & Boucher's Clinical Dental Terminology, 4th ed, p187)Radiography, Bitewing: Technique involving the passage of X-rays through oral structures to create a film record while a central tab or wing of dental X-ray film is being held between upper and lower teeth.Tooth, Nonvital: A tooth from which the dental pulp has been removed or is necrotic. (Boucher, Clinical Dental Terminology, 4th ed)Calcium Compounds: Inorganic compounds that contain calcium as an integral part of the molecule.Silicates: The generic term for salts derived from silica or the silicic acids. They contain silicon, oxygen, and one or more metals, and may contain hydrogen. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 4th Ed)Tooth Eruption: The emergence of a tooth from within its follicle in the ALVEOLAR PROCESS of the MAXILLA or MANDIBLE into the ORAL CAVITY. (Boucher's Clinical Dental Terminology, 4th ed)Receptor Activator of Nuclear Factor-kappa B: A tumor necrosis factor receptor family member that is specific for RANK LIGAND and plays a role in bone homeostasis by regulating osteoclastogenesis. It is also expressed on DENDRITIC CELLS where it plays a role in regulating dendritic cell survival. Signaling by the activated receptor occurs through its association with TNF RECEPTOR-ASSOCIATED FACTORS.Microradiography: Production of a radiographic image of a small or very thin object on fine-grained photographic film under conditions which permit subsequent microscopic examination or enlargement of the radiograph at linear magnifications of up to several hundred and with a resolution approaching the resolving power of the photographic emulsion (about 1000 lines per millimeter).Bone Remodeling: The continuous turnover of BONE MATRIX and mineral that involves first an increase in BONE RESORPTION (osteoclastic activity) and later, reactive BONE FORMATION (osteoblastic activity). The process of bone remodeling takes place in the adult skeleton at discrete foci. The process ensures the mechanical integrity of the skeleton throughout life and plays an important role in calcium HOMEOSTASIS. An imbalance in the regulation of bone remodeling's two contrasting events, bone resorption and bone formation, results in many of the metabolic bone diseases, such as OSTEOPOROSIS.Palate: The structure that forms the roof of the mouth. It consists of the anterior hard palate (PALATE, HARD) and the posterior soft palate (PALATE, SOFT).Spinal Nerve Roots: Paired bundles of NERVE FIBERS entering and leaving the SPINAL CORD at each segment. The dorsal and ventral nerve roots join to form the mixed segmental spinal nerves. The dorsal roots are generally afferent, formed by the central projections of the spinal (dorsal root) ganglia sensory cells, and the ventral roots are efferent, comprising the axons of spinal motor and PREGANGLIONIC AUTONOMIC FIBERS.Dental Stress Analysis: The description and measurement of the various factors that produce physical stress upon dental restorations, prostheses, or appliances, materials associated with them, or the natural oral structures.Dental Pulp: A richly vascularized and innervated connective tissue of mesodermal origin, contained in the central cavity of a tooth and delimited by the dentin, and having formative, nutritive, sensory, and protective functions. (Jablonski, Dictionary of Dentistry, 1992)Malocclusion: Such malposition and contact of the maxillary and mandibular teeth as to interfere with the highest efficiency during the excursive movements of the jaw that are essential for mastication. (Jablonski, Illustrated Dictionary of Dentistry, 1982)Dental Implants, Single-Tooth: Devices, usually alloplastic, surgically inserted into or onto the jawbone, which support a single prosthetic tooth and serve either as abutments or as cosmetic replacements for missing teeth.Calcium Gluconate: The calcium salt of gluconic acid. The compound has a variety of uses, including its use as a calcium replenisher in hypocalcemic states.Apexification: Endodontic procedure performed to induce TOOTH APEX barrier development. ROOT CANAL FILLING MATERIALS are used to repair open apex or DENTAL PULP NECROSIS in an immature tooth. CALCIUM HYDROXIDE and mineral trioxide aggregate are commonly used as the filling materials.Tooth Bleaching: The use of a chemical oxidizing agent to whiten TEETH. In some procedures the oxidation process is activated by the use of heat or light.Dental Pulp Cavity: The space in a tooth bounded by the dentin and containing the dental pulp. The portion of the cavity within the crown of the tooth is the pulp chamber; the portion within the root is the pulp canal or root canal.Aluminum Compounds: Inorganic compounds that contain aluminum as an integral part of the molecule.Gingivitis: Inflammation of gum tissue (GINGIVA) without loss of connective tissue.X-Ray Intensifying Screens: Screens which absorb the energy in the x-ray beam that has penetrated the patient and convert this energy into a light pattern which has as nearly as possible the same information as the original x-ray beam. The more light a screen produces for a given input of x-radiation, the less x-ray exposure and thus shorter exposure time are needed to expose the film. In most film-screen systems, the film is sandwiched between two screens in a cassette so that the emulsion on each side is exposed to the light from its contiguous screen.Orthodontic Brackets: Small metal or ceramic attachments used to fasten an arch wire. These attachments are soldered or welded to an orthodontic band or cemented directly onto the teeth. Bowles brackets, edgewise brackets, multiphase brackets, ribbon arch brackets, twin-wire brackets, and universal brackets are all types of orthodontic brackets.Ameloblastoma: An immature epithelial tumor of the JAW originating from the epithelial rests of Malassez or from other epithelial remnants of the ENAMEL from the developmental period. It is a slowly growing tumor, usually benign, but displays a marked propensity for invasive growth.Mandible: The largest and strongest bone of the FACE constituting the lower jaw. It supports the lower teeth.Malocclusion, Angle Class II: Malocclusion in which the mandible is posterior to the maxilla as reflected by the relationship of the first permanent molar (distoclusion).X-Ray Microtomography: X-RAY COMPUTERIZED TOMOGRAPHY with resolution in the micrometer range.Plant Root Cap: A cone-shaped structure in plants made up of a mass of meristematic cells that covers and protects the tip of a growing root. It is the putative site of gravity sensing in plant roots.Orthodontics: A dental specialty concerned with the prevention and correction of dental and oral anomalies (malocclusion).Stress, Mechanical: A purely physical condition which exists within any material because of strain or deformation by external forces or by non-uniform thermal expansion; expressed quantitatively in units of force per unit area.Orthodontic Appliance Design: The planning, calculation, and creation of an apparatus for the purpose of correcting the placement or straightening of teeth.Osteoblasts: Bone-forming cells which secrete an EXTRACELLULAR MATRIX. HYDROXYAPATITE crystals are then deposited into the matrix to form bone.Diphosphonates: Organic compounds which contain P-C-P bonds, where P stands for phosphonates or phosphonic acids. These compounds affect calcium metabolism. They inhibit ectopic calcification and slow down bone resorption and bone turnover. Technetium complexes of diphosphonates have been used successfully as bone scanning agents.

Histological and histochemical quantification of root resorption incident to the application of intrusive force to rat molars. (1/177)

This study was conducted to investigate the nature of root resorption resulting from intrusive forces applied to the rat lower molars, by means of histological and histochemical techniques with tartrate resistant acid phosphatase (TRAP). Thirty-eight 13-week-old Wistar strain male rats were used. Intrusive force was created by a fixed appliance which was adjusted to exert an initial force of 50 g for the duration of 1, 2, and 3 weeks. The degree of root resorption and distribution of TRAP positive cells were evaluated. On the root surface, the TRAP positive scores were low in the apical regions. Significant differences in the scores were found in the inter-radicular region of the roots between the experimental and control groups for the 2- and 3-week groups. More active resorption of bone occurred during the experimental period, as denoted by greater TRAP positive scores on the bone than on the root surface. Root resorption scores in the apical root region were larger in the 2- and 3-week groups than in the 1-week group. Significant differences in the root resorption scores were also found between the 1- and 3-week groups in the inter-radicular region, indicating that intrusive force application of a longer duration may lead to a higher frequency of root resorption. It is shown that, irrespective of the level of TRAP positive cells and root resorption scores, the degree of root resorption activity is higher in the apical root region than in the inter-radicular area. These results indicate that cellular cementum may be resorbed more easily because of its richer organic components and low mineralized structure.  (+info)

Evaluation of apical root resorption following extraction therapy in subjects with Class I and Class II malocclusions. (2/177)

The purpose of this study was to determine the amount of root resorption during orthodontic treatment, and to examine the relationship between tooth movement and apical root resorption. Twenty-seven Class I and 27 Class II patients treated with edgewise mechanics following first premolar extractions were selected. The following measurements were made on the pre- and post-treatment cephalograms: upper central incisor to palatal plane distance, the inclination of upper central incisor to the FH and AP planes, the perpendicular distances from the incisor tip to the AP and PTV planes, and incisor apex to PTV. The amount of apical root resorption of the maxillary central incisors was determined for each patient by subtracting the post-treatment tooth length from the pre-treatment tooth length measured directly on cephalograms. Intra-group differences were evaluated by the Student's t-test and inter-group differences by the Mann-Whitney U-test. For correlations the Pearson correlation coefficient was used. The results show that there was a mean of approximately 1 mm (P < 0.01) of apical root shortening in Class I patients, but in Class II division I subjects the mean root resorption was more than 2 mm (P < 0.001). The inter-group differences were statistically significant. No significant correlations were found between the amount of apical root resorption and tooth inclination, or the duration of active treatment.  (+info)

Long-term follow-up of maxillary incisors with severe apical root resorption. (3/177)

The purpose of the study was to analyse the mobility of teeth with severe orthodontically induced root resorption, at follow-up several years after active treatment, and to evaluate mobility in relation to root length and alveolar bone support. Seventy-three maxillary incisors were examined in 20 patients, 10-15 years after active treatment in 13 patients (age 24-32 years) and 5-10 years after active treatment in seven patients (age 20-25 years). All had worn fixed or removable retainers; seven still had bonded twistflex retainers. Total root length and intra-alveolar root length were measured on intra-oral radiographs. Tooth mobility was assessed clinically according to Miller's Index (0-4) and the Periotest method. Crestal alveolar bone level, periodontal pocket depth, gingival, and plaque indices, occlusal contacts during occlusion and function, and dental wear were recorded. There was a significant correlation (P < 0.05) between tooth mobility, and total root length and intra-alveolar root length. No correlation was found between tooth mobility and retention with twistflex retainers. None of the variables for assessment of periodontal status, occlusion and function were related to total root length or tooth mobility. It is concluded that there is a risk of tooth mobility in a maxillary incisor that undergoes severe root resorption during orthodontic treatment, if the remaining total root length is < or = 9 mm. The risk is less if the remaining root length is > 9 mm. Follow-up of teeth with severe orthodontically induced root resorption is indicated.  (+info)

Persistence of deciduous molars in subjects with agenesis of the second premolars. (4/177)

The purpose of the present study was to investigate persistent primary second molars in a group of young people in their late twenties with agenesis of one or two second premolars. In 1982-83 it was decided, in connection with the orthodontic evaluation of 25 patients, to allow 35 primary molars (one or two in each patient) to remain in situ. All patients had mixed dentitions and agenesis of one or two premolars. The primary teeth were generally in good condition, although root resorption and infra-occlusion (compensated by occlusal composite onlays) occurred. In 1997, 18 of the 25 patients with a total of 26 retained primary molars were reexamined, comprising a clinical examination for exfoliation, extraction, loosening, and ankylosis, and a radiographic examination for root resorption, tooth morphology (crown and root), and alveolar bone contour. The examination showed that the degree of root resorption was unaltered in 20 of the 26 primary molars. In the permanent dentitions, where these primary molars persisted, there were no morphological deviations. Three of the six remaining primary molars had been extracted and three showed extensive resorption. In three of the 26 primary molars the infra-occlusion had worsened. The present study shows that persistence of primary second molars in subjects with agenesis of one or two premolars, and normal morphology of the permanent dentition can be an acceptable, semi-permanent solution for the patient. Whether this could also be an acceptable long-term solution will be shown by follow-up studies.  (+info)

The long-term survival of lower second primary molars in subjects with agenesis of the premolars. (5/177)

This study investigated 41 subjects, 13 male and 28 female, with agenesis of one or both lower second premolars, and with retained lower second primary molars. Intra-oral radiographs of 59 primary teeth were examined to judge the resorption of the mesial and distal roots, and were measured to record infra-occlusion of the primary teeth and tipping of the adjacent permanent teeth. The study commenced at 11-12 years of age. The mean age at the last measurement was 20 years 6 months (SD 3.62, range 13.6-31.8 years). During the observation period, only two of the 59 primary teeth were exfoliated. Five were extracted, two of which were replaced by upper third molar transplants. Beyond the age of 20 years no teeth were lost. Root resorption varied widely between individuals, but was slow. There was no typical pattern for development of infra-occlusion. Mean infra-occlusion was 0.47 mm (SD 1.13) at 11-12 years, increasing by less than 1.0 to 1.43 mm (SD 1.13) at age 17-18 years. At age 19-20 years, 55 per cent of teeth showed infra-occlusion between 0.5 and 4.5 mm, but 45 per cent showed no infra-occlusion. The space between the first molar and first premolar was a mean of 10.35 mm (SD 0.76) at age 10-12 years compared with the mean width of the second primary molar of 10.53 mm (SD 0.51). The space reduced by less than 0.5 mm to 9.95 mm (SD 1.50) at age 17-18 years. If primary molars are present at 20 years of age they appear to have a good prognosis for long-term survival.  (+info)

Effect of a static magnetic field on orthodontic tooth movement in the rat. (6/177)

Orthodontic tooth movement may be enhanced by the application of a magnetic field. Bone remodelling necessary for orthodontic tooth movement involves clastic cells, which are tartrate-resistant acid phosphatase (TRAP) positive and which may also be regulated by growth hormone (GH) via its receptor (GHR). The aim of this study was to determine the effect of a static magnetic field (SMF) on orthodontic tooth movement in the rat. Thirty-two male Wistar rats, 9 weeks old, were fitted with an orthodontic appliance directing a mesial force of 30 g on the left maxillary first molar. The appliance incorporated a weight (NM) or a magnet (M). The animals were killed at 1, 3, 7, or 14 days post-appliance insertion, and the maxillae processed to paraffin. Sagittal sections of the first molar were stained with haematoxylin and eosin (H&E), for TRAP activity or immunohistochemically for GHR. The percentage body weight loss/gain, magnetic flux density, tooth movement, width of the periodontal ligament (PDL), length of root resorption lacunae, and hyalinized zone were measured. TRAP and GHR-positive cells along the alveolar bone, root surface, and in the PDL space were counted. The incorporation of a SMF (100-170 Gauss) into an orthodontic appliance did not enhance tooth movement, nor greatly alter the histological appearance of the PDL during tooth movement. However significantly greater root resorption (P = 0.016), increased width of the PDL (P = 0.017) and greater TRAP activity (P = 0.001) were observed for group M at day 7 on the compression side. At day 14 no differences were observed between the appliance groups.  (+info)

Root resorption after orthodontic treatment in high- and low-risk patients: analysis of allergy as a possible predisposing factor. (7/177)

The development of excessive root resorption during orthodontic tooth movement is an adverse side-effect, which is of great concern. The aim of this investigation was to analyse factors that might be associated with orthodontically induced root resorption. After buccal movement of maxillary premolars in 96 adolescents, the experimental teeth were extracted and subjected to histological analysis and measurement of resorbed root area. Fifty individuals, 18 boys and 32 girls, mean age 13.4 years, were selected and divided into two equal groups: the high-risk group based on measurements of the most severe root resorptions, and the low-risk group on measurements of mild or no root resorptions. After a preliminary screening of possible risk factors regarding root resorption, i.e. root morphology, gingivitis, allergy, nail-biting, medication, etc., only those subjects with allergy showed an increased risk of root resorption, but this was not statistically significant.  (+info)

A radiographic comparison of apical root resorption after orthodontic treatment with a standard edgewise and a straight-wire edgewise technique. (8/177)

The purpose of this study was to compare the severity of apical root resorption occurring in patients treated with a standard edgewise and a straight-wire edgewise technique, and to assess the influence of known risk factors on root resorption incident to orthodontic treatment. The sample consisted of 80 patients with Angle Class II division 1 malocclusions, treated with extraction of at least two maxillary first premolars. Variables recorded for each patient included gender, age, ANB angle, overjet, overbite, trauma, habits, invagination, agenesis, tooth shedding, treatment duration, use of Class II elastics, body-build, general factors, impacted canines, and root form deviation. Forty patients were treated with a standard edgewise and 40 with a straight-wire edgewise technique, both with 0.018-inch slot brackets. Crown and root lengths of the maxillary incisors were measured on pre- and post-treatment periapical radiographs corrected for image distortion. Percentage of root shortening and root length loss in millimetres were then calculated. There was significantly more apical root resorption (P < 0.05) of both central incisors in the standard than in the straight-wire edgewise group. No significant difference was found for the lateral incisors. Root shortening of the lateral incisors was significantly associated with age, agenesis, duration of contraction period (distalization of incisors), and invagination, while root shortening of the central incisors was related to treatment group and trauma.  (+info)

  • It is suggested that significant root resorption occurs when the force magnitude exceeds 1.6 g in the rat upper first molar during tipping tooth movement by continuous force, and the amount of root resorption increases with serial force magnitudes from 0.8 to 4 g. (
  • However, the literature have pointed out that torque tooth movement, especially when the root apices are torques against cortical plates of bone produces the most dramatic type of tooth root resorption with poor prognosis. (
  • The experimental groups with 4 and 8 g force showed undermining bone resorption with degenerating tissue and marked root resorption, the 1.6 g group showed only root resorption, while the 0.8 g group was similar to the control. (
  • Moreover, a pause in tooth movement seems to be beneficial in reducing root resorption because it allows the resorbed cementum to heal. (
  • Physical properties of root cementum: Part 25. (
  • During later stages of tissue reactions, the majority of the cells involved in removal of the necrotic tissues and resorption of the root surfaces are multinucleated TRAP-positive cells that, when reaching the subjacent contaminated and damaged root surface after having removed necrotic tissue, continue to remove the cementum surface. (
  • If you have been in clinical practice for more than five years, you have probably thought that you are now seeing a lot more cases of root resorption than you ever did before. (
  • If you have been in clinical practice for more than 20 years, you are probably thinking that there is a new epidemic of root resorption. (
  • In fact, the pulp in these teeth remain vital and the resorption tends to navigate around the pulp canal (hence the alternate designation of extra-canal invasive root resorption). (
  • This was not met with great success - but with no surprise, since the pulp in these teeth are normal, unless there was an underlying pre-condition (noting that this type of resorption often occurs on virgin teeth). (
  • Orthodontic treatment seems to be corelated with invasive cervical root resorption and in a small study, a particular feline herpetic virus has been associated with it (yes, a cat virus, noting that about 50% of cat teeth have this type of defect). (
  • Orthodontic tooth movement involves a series of biologic reactions after force application, which makes teeth vulnerable to root resorption. (
  • A significant reduction in the root length can cause an unfavorable crown-root ratio of the affected teeth. (
  • Root and crown lengths of a total of 1600 teeth were measured twice in pre- and post-treatment panoramic radiographs. (
  • All patients had a reduction of the pre-treatment root length with a minimum of two teeth. (
  • 54% of 1600 measured teeth showed no measurable root reduction. (
  • A minimum of two teeth with a root length reduction was found in every patient. (
  • At the end of the experimental period, the teeth were carefully extracted and processed for 3-dimensional imaging and volumetric evaluations of resorption craters. (
  • However, statistically significant differences were observed between heavy and light jiggling forces ( P = 0.038), with heavy jiggling forces causing greater total root resorption than light jiggling forces. (
  • Light microscopic images of the compressed periodontal ligament (PDL) were processed by computer, and the ratio of the root resorption lacuna length to root surface length without the lacuna was analysed and statistically compared using Tukey-Kramer multiple comparison honestly significant difference test. (
  • So, the big question is: if you reflect a full thickness gingival flap from the sulcus, remove the resorption defect, place a restoration in the defect, and suture the flap back in place, will the gingival healing result in a gingival and bony dehiscence over the root surface? (
  • The purpose of this study was to assess the rate of root resorption in relation to different magnitudes of continuous force during experimental tooth movement using nickel-titanium (NiTi) alloy wire. (
  • Light and heavy jiggling forces in the buccopalatal direction did not cause significantly different amounts of root resorption when compared with continuous forces of the same magnitude. (
  • Continuous vs jiggling forces of the same magnitude produce similar volumes of root resorption. (
  • When considering whether to treat these types of defects, there are two main considerations: the speed of the defect's progression, and how much resorption has taken place, both of which are difficult to assess. (
  • A comparison of the ability to assess resorptions on two-dimensional (2D) and three-dimensional (3D) radiographs is, hitherto, lacking. (