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PubMed2001

Maxillary unilateral molar distalization with sliding mechanics: a preliminary investigation.

Fifteen patients, eight males and seven females with a mean age of 13.32 years, were selected for unilateral molar distalization. Dentally, all presented with a unilateral Class II molar relationship. The subjects were all in the permanent dentition with second molars erupted and with a well aligned lower dental arch. For maxillary molar distalization a new intra-oral appliance was developed, the Keles Slider, which comprised two premolar and two molar bands. The anchorage unit was a Nance button with an anterior bite plane. From the palatal side, the point of distal force application was carried towards the level of centre of resistance of the maxillary first molar. A Ni-Ti coil spring was used and 200 g distal force was applied to the Class II first molar. Lateral cephalograms were taken and analysed before and 2 months after molar distalization. The Class II molars were distalized bodily, on average, 4.9 mm (P < 0.001). Mesial migration of the Class II first premolars was 1.3 mm (P < 0.05), incisor protrusion was 1.8 mm (P < 0.05) and incisor proclination 3.2 degrees (P < 0.05). The overbite was reduced by 3.1 mm (P < 0.001) and the overjet increased 2.1 mm (P < 0.01). For stabilization, the corrected Class II unilateral molar relationship was maintained with a Nance button for 2 months. The results show that this newly developed device achieved bodily distal molar movement with minimum anchorage loss.

Adolescent↗
PubMed1986

Mandibular molar displacement secondary to the use of forces to retract the maxilla.

Using previously described computer-aided techniques, we have been able to characterize quantitatively the displacements of the lower first molar associated with the use of several different therapeutic modalities that are conventionally employed to retract the maxilla in the treatment of Class II malocclusion. The total displacement of the molar has been partitioned into two components associated respectively with displacement of the entire mandible and with local interosseous migration (dental compensation) of the molar within the mandible. A further attempt has been made to partition treatment-associated effects from nontreatment-associated effects. While considerable variability in effect was observed within each sample on a case-by-case basis, some important normative trends did emerge. Contrary to our expectations, it was found that in each of the treatment groups, the mean local intraosseous rotational effect (Table IIB.2) was of greater magnitude than the mean effect of mandibular rotation (Table IIB.1). The character of the intraosseous rotation differed significantly (P less than 0.05) between the control group and each of the treatment groups. In the control group, a mean mesial crown tipping (that is, "proclination") was noted. In each of the treatment groups, a mean distal crown tipping ("uprighting") was noted. In both the cervical and intraoral groups, the lower molar tended to displace mesially more than in the control or high-pull groups. This mesial displacement derived from the mesial displacement of the mandible (Table IIC.3), rather than from displacement of the tooth within the bone (Table IIC.4). In both the high-pull and the intraoral groups, the lower molar erupted within the mandible significantly more than in the control and cervical groups (Table IIC.6). The statistically significant supereruption/extrusion of the upper molar in the cervical group (Table IIC.2) was not accompanied by an associated inhibition of the eruption of the lower first molar (Table IIC.6). In general, it seems reasonable to infer that the growth-related displacement of the mandible influenced the final position of the lower first molar more profoundly than did the treatment-associated displacement of the upper molar.

Activator Appliances↗
PubMed1988

Light microscopic and transmission electron microscopic study of initial phases of giant tubule formation in bovine dentin.

Bovine tooth germs dissected from the mandible immediately after bleeding of the less than 1-yr-old calves (Bos taureus) were used to study the initial phases of giant tubule (GT) formation. Three stages could be discerned. Firstly, the initial manifestations were represented by loci about 150 micron apart in the axiomesiodistal plane along the pulpal border of the 100-200-micron-thick incisal dentin. Some of these loci showed only a blunt capillary loop and associated cells, whereas in most others there was a 50-100-micron-wide dense matrix consisting of coarse collagen fibrils and showing a metachromatic staining reaction to toluidine blue. Fibroblasts lined this matrix, and a capillary loop was always present underneath. Both kinds of GT origins were eventually circumvented by the odontoblasts situated incisal to them. The matrices became enclosed in the dentin. In the second stage, the GT grew in length as new dentin was formed. In this stage the vascular loops and the adjoining fibroblasts remained stationary within the GT lumina relative to the origins. In the third stage the GT vessels started to migrate pulpally relative to the origins. This seemed to be the result of a sequestration of the most incisal portions of the vascular loops. In this last stage the formation of collagen fibrils in the GT lumen incisal to the vessel loops started.

Animals↗
PubMed1977

Plaque control in the treatment of juvenile periodontitis.

With the purpose of establishing to what extent "periodontosis" responds to total plaque control, 21 such patients were observed over periods ranging from 8 to 34 years. Total plaque control in the present context means complete removal of all supragingival plaque by the patient and complete removal of all subgingival plaque by the dentist. The results were evaluated in terms of the number of lost teeth and the percentage of lost attachment during the observation period. It was observed that "periodontosis" cases responded to total plaque control in the same way as do ordinary cases, but with periodontosis, incomplete plaque control on any teeth led to extremely rapid bone loss and eventually to extraction. The reason for this is the unusually rapid apical migration of the subgingival plaque which is the most typical feature of the juvenile periodontitis. Some attachment and some teeth were lost in most of the patients, but a sufficient number of teeth with a sufficient amount of supporting tissue were maintained to provide a set of natural teeth that functioned well. This study shows that the reduced resistance to the invasion of subgingival plaque can be compensated for by a correspondingly strong emphasis on total plaque control. The term "periodontosis" is misleading, and should be replaced by the name "juvenile periodontitis" as suggested by Lehner et al. (1974).

Adult↗
PubMed2005

Hypohidrotic ectodermal dysplasia with bilateral impacted teeth at the coronoid process: a case rehabilitated with mini dental implants.

Bilateral migration of teeth into the coronoid process in a patient with ectodermal dysplasia has not been reported in the literature except one report in which severe hypodontia and bilaterally ectopic impacted teeth in the coronoid processes of a nonsyndromic patient occurred. This article presents a 15-year-old female with hypohidrotic ectodermal dysplasia who had surgical removal of bilaterally impacted teeth in the coronoid process and was rehabilitated with a dental implant-retained fixed prosthesis in the mandible and over-denture in the maxilla.

Adolescent↗
PubMed1987

Cell and fiber attachment to demineralized dentin. A comparison between normal and periodontitis-affected root surfaces.

The purpose of the present study was to compare and contrast cellular, connective tissue, and epithelial responses to dentin specimens derived from the roots of either normal or periodontitis-affected human teeth after surface demineralization. Rectangular dentin specimens, with opposite faces of root and pulpal dentin, were derived from beneath root surfaces covered by periodontal ligament (normal) or calculus-covered areas of periodontitis-affected teeth. In each of the groups, the specimens were treated with citric acid (pH 1 for 3 min), whereupon they were implanted transcutaneously into incisional wounds on the dorsal surface of rats with one end of the implant protruding through the skin. 4 specimens were available in each group at 10 days after implantation. Histologic and histometric analyses of the root surfaces of the implants included counts of adhering cells, evaluation of connective tissue fiber relationships, and assessment of epithelial migration. New connective tissue attachment with inhibition of epithelial migration occurred in both groups. Cementum formation was not present. Comparisons between the groups showed no significant differences regarding length of implant surface adjacent to connective tissue, number of attached cells, or density and diameter of attached fibers. The fiber attachment system which had developed on these demineralized surfaces seemed intrinsic to the connective tissue location, and differed morphologically from corresponding fibers attaching the root surface in a normal periodontium. It was concluded that there were no observable differences between the new connective tissue attachment systems which developed on demineralized dentin from either normal or periodontitis-affected root surfaces.

Animals↗
PubMed2006

Plasminogen activators and inhibitor type-1 in alveolar osteitis.

Alveolar osteitis (AO) is characterized by excess fibrinolysis, leading to early dissociation of the clot that normally follows tooth extraction. Nonetheless, scarce information is available on the fibrinolytic system in AO. In this study, we report on the differential composition of postextraction wound healing tissue and of peri-alveolar gingival epithelium from normal healing and AO patients in terms of plasminogen activators, plasminogen activator inhibitor-type 1, and urokinase-type plasminogen activator receptor. Plasminogen activators were studied by overlay zymography, western blotting, and enzyme-linked immunosorbent assay (ELISA). Plasminogen activator inhibitor-type 1 and urokinase receptor were measured by ELISA. In AO, the fibrinolytic activity of wound healing tissue was accounted for by an increase ( approximately 85%) of urokinase-type plasminogen activator, whereas tissue-type plasminogen activator was unchanged. Plasminogen activator inhibitor-type 1 showed a 6.7-fold increase in AO. These results point to key roles of urokinase in AO hyper-fibrinolysis and of plasminogen activator inhibitor type-1 in slowing down the healing response. Peri-alveolar gingival epithelium in AO showed an overall decrease of all the components of the fibrinolytic system, including the urokinase receptor, which indicates a decrease of the migration properties of epithelial cells.

Adult↗
PubMed1984

Advances in the dental search for Native American origins.

The Sinodont dental morphology pattern of NE Asia is today more complex and was so by 20,000 years ago, than the simplified Sundadonty of SE Asia-Oceania, and the very simplified pattern that evolved greater than 20,000 B.P. All Native Americans are Sinodonts. Intra--and inter-hemispheric statistical analyses of 28 dental traits in greater than 6000 N & S American and greater than 1100 NE Asian crania reveal three temporally stable American sub-patterns, suggesting prior evolution in Sino-Siberia. The hypothesized biocultural associations and migration episodes are: (1) "Upper Cave" Sinodonts with the generalized Chinese Microlithic Tradition reach the Arctic steppe via the Lena basin to become Paleo--and most later Indians. (2) Smaller-game-hunting Siberian Diuktaians cross to Alaska at forest-forming terminal land bridge times to become Paleo-Arctic and subsequent Na-Dene-speaking NW forest Indians. (3) Lower Amur basin-N Japan blade-makingfolk evolve a coastal culture on the way to the land bridge's SE terminus at Anangula-Umnak where the oldest skeletons of the dentally distinctive but variable Aleut-Eskimos have been found.

Americas↗
PubMed2001

The use of enamel matrix derivative in the treatment of periodontal osseous defects: a clinical decision tree based on biologic principles of regeneration.

An investigation of the periodontal literature reveals four critical factors necessary for a regenerative response in the treatment of intrabony defects. These include root preparation to remove toxins and altered cementum, space creation by the graft or membrane barrier for migration of progenitor cells, stabilization and flap coverage of the graft, and use of a membrane barrier or enamel matrix derivative (EMD). This article reviews the literature supporting this concept and presents a clinical decision tree to determine when to use EMD alone or with autogenous grafts and membrane barriers in the treatment of defects of varying morphologies. The clinical decision tree is designed to increase the predictability of a positive clinical response. Cases are shown to demonstrate the indication for each treatment.

Adult↗
PubMed1995

[Removal through the coronal approach of the upper wisdom teeth. Apropos of a case of bilateral migration into the temporal fossa].

This report presents a case of double migration of third maxillary molar in temporal fossa and their removal by a coronal approach. A 15 years of old boy, was seen for major trismus. 2 months before, he underwent under general anaesthesy impacted third maxillary molar removal. The radiologic examination showed that superior third molar has been pushed and left into the temporal fossa in both sides. After computed tomography examination, teeth were removed by a coronal approach. This was the only approach in order to preserve facial nerve and to allow with good chances to remove the teeth. Intervention was successful. Postoperative course was uneventful. The buccal apperture was normalized three months after surgery.

Adolescent↗
PubMedDate not supplied

Histologic characteristics of the gingiva associated with the primary and permanent teeth of children.

The severity of the gingival inflammatory response to dental plaque increases with age, and it has been suggested that this phenomenon may be related to histological characteristics of the gingiva. The objective of this study was to compare the histological characteristics of the gingival tissues of primary teeth with that of permanent teeth in children. Prior to extraction, children were subjected to a period of thorough oral hygiene. Histological sections prepared from gingival biopsies were examined using the light microscope. One biopsy from each of seven primary and seven permanent teeth of 14 children, whose mean ages were 11.0 +/- 0.9 and 12.9 +/- 0.9 years respectively, was obtained. All sections exhibited clear signs of inflammation. Apical migration of the junctional epithelium onto the root surface was associated only with the primary teeth. Compared with the permanent teeth, the primary teeth were associated with a thicker junctional epithelium (P < 0.05), higher numbers of leukocytes in the connective tissue adjacent to the apical end of the junctional epithelium (P < 0.05), and a higher density of collagen fibers in the suboral epithelial connective tissue (P < 0.01). No significant differences were noted in the width of the free gingiva, thickness of the oral epithelium, or its keratinized layer. In conclusion, this study indicates significant differences in the microanatomy of the gingival tissues between primary and permanent teeth in children.

Child↗
PubMed2005

An in vitro model to measure the effect of a silver fluoride and potassium iodide treatment on the permeability of demineralized dentine to Streptococcus mutans.

BACKGROUND: Diamine silver fluoride (Ag(NH3)2F), referred to as AgF, has been used to reduce the incidence of caries in primary dentitions but has been limited by the associated staining of both teeth and restorative materials. The application of potassium iodide (KI), following AgF prevents staining but its effects on the ability of AgF to reduce caries are not known. The aim of this study was to develop an in vitro model that would provide an indication of the permeability of demineralized dentine to Streptococcus mutans after treatment of the dentine with AgF followed by KI. METHODS: Forty dentine discs were bonded to the base of forty 5mL polycarbonate screw top vials (that had had their bases removed), filled with nutrient medium, sterilized and placed into a continuous culture of S. mutans. Samples were divided into four groups as follows: 10 samples of demineralized dentine as a control, 10 samples of demineralized dentine treated with AgF/KI, 10 samples of demineralized dentine treated with KI and 10 samples of demineralized dentine treated with AgF. After two weeks the optical density of the growth medium chambers was measured to determine bacterial penetration and growth. Cultures were plated out to determine migration through the discs by S. mutans. RESULTS: S. mutans migrated through all dentine discs. However, the samples treated with AgF and AgF/KI had significantly lower optical densities than the corresponding controls. The range of optical densities was least amongst demineralized samples treated with AgF/KI. CONCLUSIONS: Under the conditions of this study, treatment of demineralized dentine discs with AgF followed by KI allowed the penetration of S. mutans. Based on optical density measurements, the treatment resulted in significantly fewer microorganisms being present subjacent to the discs treated with AgF and KI than the control discs at the end of the experimental period.

Bacteriological Techniques↗
PubMed2002

Effect of surgical implantation of recombinant human bone morphogenetic protein-2 in a bioabsorbable collagen sponge or calcium phosphate putty carrier in intrabony periodontal defects in the baboon.

BACKGROUND: Recombinant human bone morphogenetic protein-2 (rhBMP-2) in a proper carrier has been shown to induce clinically relevant bone formation for several oral/maxillofacial and periodontal indications and to stimulate regeneration of the periodontal attachment. The objective of this study is to evaluate regeneration of alveolar bone, cementum, periodontal ligament, and associated root resorption and ankylosis following surgical implantation of rhBMP-2 in an absorbable collagen sponge (ACS) or a calcium phosphate putty (alphaBSM) carrier in 3-wall intrabony periodontal defects in the baboon. METHODS: rhBMP-2/ACS and rhBMP-2/alphaBSM were implanted in surgically produced, maxillary and mandibular, large size, 3-wall intrabony defects in 4 baboons. Contralateral jaw quadrants were implanted with buffer/ACS, buffer/ alphaBSM, or served as sham-operated surgical controls. Treatments were allocated to left and right, maxillary and mandibular, jaw quadrants following a randomization schedule. Four months following implantation, block biopsies of defect sites were obtained, processed, and subjected to histologic and histometric analysis. RESULTS: Defect sites receiving rhBMP-2/ACS and rhBMP-2/alphaBSM demonstrated significantly greater regeneration than controls. No significant differences were observed between defect sites receiving rhBMP-2/ACS or rhBMP-2/alphaBSM regarding epithelial migration and connective tissue attachment and new bone formation. However, rhBMP-2/ACS supported significantly greater new cementum formation. Ankylosis or root resorption were not observed. CONCLUSIONS: The results of this study support the use of rhBMP-2 to enhance periodontal regeneration of intrabony periodontal defects. While this novel technology holds promise, refinement in carrier systems may provide the key to enhancement of the regenerative potential.

Alveolar Bone Loss↗
PubMed1984

A histometric evaluation of the effect of citric acid preparation upon healing of coronally positioned flaps in nonhuman primates.

Facial recession defects were created on maxillary canine teeth of six Macaca irus monkeys and left untreated and exposed to oral fluids for 6 to 12 weeks. Notches were placed in the exposed root surfaces at the level of the free gingival margins. Following root planing with the addition of topical citric acid application on experimental surfaces, pedicle flaps were coronally positioned over the previously exposed roots. After euthanasia, block sections representing postsurgical time periods of 0, 3, 7, 14, 21, 28 and 42 days were secured and tissues were processed for histologic evaluation. All citric acid-treated surfaces exhibited new connective tissue attachment of pedicle flaps to previously exposed areas by 14 days with transmission electron micrographs confirming beginning cementum deposition. In contrast, controls demonstrated epithelial migration to, or apical to, reference notches. Although the total number of samples available for statistical comparison was small, a two-tailed t test for correlated samples showed citric acid application did not result in enhanced clinical root coverage, but did result in significantly greater amounts of new connective tissue attachment (P less than 0.05, df = 3). Pedicle flap healing against teeth with devital pulps was identical to that seen in teeth with vital pulps, while citric acid application to root-planed surfaces of vital teeth had no observable effect upon pulpal tissues.

Animals↗
PubMed1996

Production of amelogenin by enamel epithelium of Hertwig's root sheath.

OBJECTIVE: To study the multiple potentials of differentiating odontogenic epithelial cells. STUDY DESIGN: Bilateral first and second maxillary molars of 30 immature rats were perforated into the pulp chambers with a round bur. The pulps were observed histologically and immunohistochemically for amelogenin 3, 7, and 14 days after the perforation. RESULTS: On day 7, the enamel epithelium of Hertwig's root sheath migrated and formed oval-shaped epithelial islands that resembled epithelial rests of Malassez. On day 14, the islands consisted of epithelial cells with large nuclei and cytoplasm partially surrounded by a subsequently formed osteodentin and cementum. Immunoreactivity for amelogenin was observed in the large epithelial cells and in the area between the cells as well as the calcified tissues. Some of the enamel epithelium resembling columnar ameloblasts of the enamel organ were also positive for amelogenin. CONCLUSIONS: The enamel epithelium of Hertwig's root sheath appeared to differentiate into ameloblasts and produce amelogenin.

Ameloblasts↗
PubMed2000

Eruption Guidance Appliance effects in the treatment of Class II, Division 1 malocclusions.

The objective of this research was to cephalometrically evaluate the possible effects of the Eruption Guidance Appliance on the craniofacial complex in a sample of 30 patients, over a treatment period of 26 months. The experimental sample consisted of 30 patients (13 females and 17 males), 27 of which presented with a Class II, Division 1 malocclusion and 3 with a Class I malocclusion. The mean initial chronologic age was 9 years; the treatment period lasted 26 months. A control group was used for comparison and consisted of 30 subjects (13 females and 17 males) of similar ages and spanned a similar observation period. Twenty-six subjects of this control group had Class II, Division 1 malocclusions, and 4 had Class I malocclusions. Lateral cephalometric headplates were obtained for the experimental group initially and after 26 months of treatment. The subjects in the control group were randomly selected from a serial growth study sample from the Orthodontic Department at Bauru Dental School, University of São Paulo, for whom cephalometric headplates were obtained annually from 4 to 18 years of age. Comparative statistics were used to assess possible differences between the experimental and control groups during the 26-month period of observation. Results demonstrated statistically significant increases in mandibular growth, degree of mandibular protrusion, lower anterior and total anterior face height, mesial migration of the lower molars, and mandibular posterior dentoalveolar height. There was also lingual tipping and retrusion of the upper incisors, linear protrusion of the lower incisors, improvement in the maxillomandibular relationship and in molar relationship, as well as a significant decrease in the overjet and overbite and an inhibition of the vertical development of the upper incisors. The study demonstrated no significant changes in maxillary growth during the evaluation period. It was concluded from these results that the effects of the Eruption Guidance Appliance during this time period were mostly dentoalveolar, with a smaller, but significant, skeletal effect.

Cephalometry↗
PubMed2002

Novel functions of the matricellular proteins osteopontin and osteonectin/SPARC.

Osteopontin (OPN) and osteonectin/SPARC (ON/SPARC) are prominent matricellular components of the extracellular matrix of mineralized tissues of bones and teeth in which they can regulate the formation and growth of hydroxyapatite crystals and influence a variety of cell activities. OPN regulates cell responses through several integrin receptors and is also a ligand for the CD44 receptor, through which it acts as a chemoattractant. Although a cell-surface receptor for SPARC has not been identified it can block cell-cell and cell-matrix interactions and inhibit cell migration and chemotaxis. OPN and SPARC also appear to function inside cells. Thus, OPN appears to exist in association with the CD44 receptor inside migratory cells, while intracellular SPARC is associated with axonemal tubulin in ciliated epithelial cells. Analyses of fibroblasts and peritoneal macrophages from OPN-null and CD44-null cells show impaired functionality involving migration and cell fusion required for osteoclast formation, while disruption of SPARC expression leads to developmental defects in Xenopus. To gain further insights into the intracellular functions of OPN and SPARC, we have used the yeast two-hybrid system to identify potential interacting molecules. Using full-length SPARC as bait the carboxy-terminal domain, which contains two EF-hand, high-affinity binding sites, was found to have transcriptional activity, while several novel proteins that interact with the amino-terminal domains of SPARC and full-length OPN have been identified. The identification of OPN and SPARC inside specialized cells introduces a novel concept in cellular regulation by matricellular proteins.

Animals↗
PubMed1998

Unbiased quantitative testing of conventional orthodontic beliefs.

This study used a preexisting database to test in hypothesis from the appropriateness of some common orthodontic beliefs concerning upper first molar displacement and changes in facial morphology associated with conventional full bonded/banded treatment in growing subjects. In an initial pass, the author used data from a stratified random sample of 48 subjects drawn retrospectively from the practice of a single, experienced orthodontist. This sample consisted of 4 subgroups of 12 subjects each: Class I nonextraction, Class I extraction, Class II nonextraction, and Class II extraction. The findings indicate that, relative to the facial profile, chin point did not, on average, displace anteriorly during treatment, either overall or in any subgroup. Relative to the facial profile, Point A became significantly less prominent during treatment, both overall and in each subgroup. The best estimate of the mean displacement of the upper molar cusp relative to superimposition on Anterior Cranial Base was in the mesial direction in each of the four subgroups. In only one extraction subject out of 24 did the cusp appear to be displaced distally. Mesial molar cusp displacement was significantly greater in the Class II extraction subgroup than in the Class II nonextraction subgroup. Relative to superimposition on anatomical "best fit" of maxillary structures, the findings for molar cusp displacement were similar, but even more dramatic. Mean mesial migration was highly significant in both the Class II nonextraction and Class II extraction subgroups. In no subject in the entire sample was distal displacement noted relative to this superimposition. Mean increase in anterior Total Face Height was significantly greater in the Class II extraction subgroup than in the Class II nonextraction subgroup. (This finding was contrary to the author's original expectation.) The generalizability of the findings from the initial pass to other treated growing subjects was then assessed by retesting modified hypotheses against a second database stored sample that earlier had been drawn randomly from two other orthodontic practices. The implications of the author's study strategy to the design of future shared digital databases is discussed briefly.

Cephalometry↗