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At least 199 records · Page 11Linked to original sources
PubMed1991

Pulp capping of immature teeth with anatomic anomalies.

This case report describes the treatment of two immature teeth with anatomic anomalies which created plaque retentive areas and in one case occlusal disturbance. Periodontal and pulpal consequences were inevitable. Reshaping of the teeth was carried out which as expected led to exposure of the pulp in both instances. Pulp capping was then performed under aseptic conditions. The vitality of the teeth was maintained and continued root development was observed.

Adolescent↗
PubMed1993

Epidemiology of root caries.

Many epidemiological studies have been conducted on a variety of populations. Unfortunately, comparison of the prevalence data, and to a lesser degree of the incidence data, between the various studies is of little use due to the lack of standardised diagnostic criteria, reporting methods and population diversity. In the few incidence studies which have been conducted around 30-40% of people developed root caries, although many adults in the population appear to have been affected by root caries. Many risk factors associated with the occurrence of root caries have been identified and these include oral, medical, mental, behavioural and psychosocial conditions.

Adolescent↗
PubMed1989

Pulpal healing after luxation injuries and root fracture in the permanent dentition.

Pulpal healing patterns were studied in a clinical material of 637 luxated and 95 root-fractured permanent incisors followed routinely for up to 11 years. It was found that pulpal healing patterns could generally be divided into 3 groups according to the degree of injury sustained by the pulp: little, moderate or severe. Thus after luxation injuries, pulp survival could be without radiographic change (PS), with pulp canal obliteration (PCO) or nonhealing (pulp necrosis (PN]. After root fracture, similar healing patterns could be observed: healing by hard tissue union of fragments (HT), by connective tissue union of fragments (CT) or by nonunion due to interposition of granulation tissue between fragments (GT) resulting from PN of the coronal fragment. In both trauma situations, healing or nonhealing could be determined by type of luxation injury, stage of root development and type of fixation used (forceful application of orthodontic bands vs. passively applied acid-etch fixation). Pulpal healing complications (PN or GT) were based on clinical findings (coronal discoloration, loss of pulpal sensibility) and radiographic findings (resorption processes of the lamina dura at the root apex or at the level of the root fracture). However, in both injury groups the same changes could also be seen to be intermediate steps in the pulpal healing process. Based on findings from these studies, hypotheses for the mechanics of pulpal healing are proposed as well as guidelines for acute and later treatment of dental luxations, root fractures and the diagnosis of healing complications.

Dental Pulp↗
PubMed1989

Hertwig's epithelial root sheath differentiation and initial cementum and bone formation during long-term organ culture of mouse mandibular first molars using serumless, chemically-defined medium.

Studies were designed to test the hypothesis that Hertwig's epithelial root sheath (HERS) synthesizes and secretes enamel-related proteins that participate in the process of acellular cementum formation. Our experimental strategy was to examine sequential root development of the mouse mandibular first molar in vivo and in long-term organ culture in vitro using serumless, chemically-defined medium. Using anti-amelogenin, anti-enamelin and anti-peptide antibodies, enamel-related antigens were localized within intermediate cementum during HERS differentiation and root formation in vivo. Cap stage molars maintained for periods of up to 31 days in organ culture expressed morphogenesis and cytodifferentiation as identified by tooth crown and initial root, cementum and bone formation. Metabolically-labeled HERS products were analyzed by immunodetection using enamel-related antibodies and one- and two-dimensional SDS gel electrophoresis. A 72 kDa and 26 kDa polypeptide were identified in forming mouse cementum. Both of these root putative cementum proteins yield similar (identical) amino acid compositions; however, both proteins differed from the compositions of either mouse crown enamelin or amelogenin proteins. This approach provides a new and novel in vitro model towards understanding HERS differentiation and functions related to root and bone formation. The data support the hypothesis that HERS cells synthesize polypeptides related to but also different from canonical crown enamel proteins.

Animals↗
PubMed1984

Access cavity preparation.

The endodontic access cavity is an essential component of the endodontic triad upon which all subsequent canal preparation and filling is based. It is probably the most frequently underemphasized aspect of endodontic therapy. This results in great clinical frustration and poor immediate and long-term results for the practitioner. The access cavity must provide clear and unobstructed access to each and every orifice and must be designed in such a way so as not to interfere with the often difficult intracanal procedures to follow. An understanding of root development, chamber, and canal anatomy will allow the practitioner to more easily debride and seal each canal through proper access cavity preparation.

Dental Pulp Cavity↗
PubMed1993

Transient expression of beta-NADPH diaphorase in developing rat dorsal root ganglia neurons.

We report here that during early fetal rat development, most, if not all, dorsal root ganglion (DRG) cells were stained by the beta-NADPH diaphorase histochemical reaction, indicating that they expressed nitric oxide synthase. During late fetal development, most DRG cells lost their diaphorase activity, but a small subset (located in all DRGs, but primarily in mid-thoracic DRGs) remained diaphorase-positive in adult animals. The transient expression of this enzyme suggests that nitric oxide may play a role during development that differs from its function in mature cells.

Amino Acid Oxidoreductases↗
PubMedDate not supplied

[Nonsurgical endodontic treatment of an invaginated canine].

We present a case of a maxillary canine with a dens invaginatus treated successfully. The patient had pain, swelling and a sinus tract coming from the inmature apex of the canine. The canals were enlarged and cleaned and the main canal was filled with Calcium Hydroxide to allow the root development. Seven months later, the patient was asymptomatic and the tooth was obturated with guttapercha. One year later it was confirm the success in the treatment.

Adolescent↗
PubMed1976

Root fractures in permanent anterior teeth with incomplete root formation.

A follow-up study was made of seven teeth with incomplete root formation observed in a group of 66 permanent teeth with root fracture. Three fractures were overlooked on the initial radiographs, two other teeth were suspected of being fractured, and an accurate diagnosis was made in two cases only. All teeth exhibited markedly increased mobility at the initial examination, and slight dislocation of the coronal fragment was found in two teeth. Following reduction (two teeth) and fixation (all teeth), the observation period ranged from 1 1/2 to 19 years. Retained pulp vitality, repair in the fracture area and, most important, approximately normal root development with closure of the apical foramen were observed in all teeth. Even the occurrence of re-fracture in two semmingly repaired teeth did not jeopardize the long-term result.

Child↗
PubMed1988

1987 Kreshover lecture. Gene regulation in the development of oral tissues.

The regulatory processes associated with tooth formation are being investigated by the identification of when, where, and how cell adhesion molecules (CAMs), substrate adhesion molecules (SAMs), dentin phosphoprotein, enamel gene products, and intermediate cementum products are expressed during sequential developmental stages of morphogenesis, cytodifferentiation, dentin, enamel and cementum extracellular matrix (ECM) formation, and biomineralization. Instructive and permissive signaling is required for both morphogenesis and cytodifferentiation based upon in vitro organotypic culture studies in serumless, chemically-defined medium. Intrinsic developmental instructions, independent of exogenous growth factors, mediate tooth morphogenesis from the initiation of the dental lamina through crown and initial root development. Recent progress using recombinant DNA methods has advanced descriptions of several dental structural genes. The complete nucleic acid sequence for mouse amelogenin has been defined. This sequence is located on the mouse X chromosome and on the human X and Y chromosomes. This discussion summarizes recent results using experimental embryology, recombinant DNA technology, and immunocytology in the context of instructive epithelial-mesenchymal interactions associated with epithelial differentiation into ameloblasts, ectomesenchyme differentiation into odontoblasts, and dentin and enamel ECM biomineralization. The tooth organ provides opportunities at several levels of biological organization to investigate cellular, molecular, and developmental processes.

Animals↗
PubMed1987

Redistribution of Schwann cells in developing feline L7 ventral spinal roots.

The length and distribution of Schwann cells along fibres in the ventral root L7 of the developing cat have been studied electron microscopically in serial sections. The average Schwann cell length at the beginning of myelin formation - the 'initial internodal length' - was 118 micron (110 micron in alpha-axons and 124 micron in gamma-axons). The number of Schwann cells found in a fully developed root segment was already present at the beginning of the myelination. It showed no systematic age-dependent variation from the beginning of myelination to adulthood. The Schwann cells associated with alpha-axons increased their length 12.6 times during this period, while the root elongated 5.6 times. About 50% of the Schwann cells had to be eliminated in order to make the elongation of the remaining Schwann cells possible. Corresponding calculations from the mean length of Schwann cells associated with gamma-axons, showed that about 50% too few Schwann cells were associated with the gamma-axons during the period of initial myelination of the alpha-axons. At birth, when the myelination of gamma-axons had just begun, both the large surplus along alpha-axons and the deficit along gamma-axons had disappeared. We suggest that Schwann cells are eliminated from the alpha-axons and re-utilized along the gamma-axons. During this process of cellular redistribution, affected cells constitute so-called aberrant Schwann cells.

Age Factors↗
PubMed1990

A radiographic four-year follow-up study of asymptomatic mandibular third molars in young adults.

Fifty-five asymptomatic mandibular third molars (M3) in 34 dental students (mean age 20.6 years at the start of the study) were followed radiographically for 4 years. Based on clinical evaluation the 55 teeth included 20 almost erupted, 13 partly erupted and 22 non-erupted M3. The following were assessed on the radiographs: root development, level of eruption, sagittal angulation, resorption, pericoronitis/bony pockets/paradental cysts and widening of the periodontal space/dentigerous cysts. The state of 21 teeth (38 per cent) was radiographically changed at the end of the observation period. The most remarkable finding was that 15 teeth changed their sagittal angulation, all in a distal direction; five mesioangular to vertical, five vertical to distoangular, five mesioangular to distoangular. Radiographically, 13 M3 moved to a more advanced level of eruption. No real pathological osseous lesions and no root resorption were observed at initial or follow-up examinations. It is concluded that there are frequent essentially unpredictable changes in the position of M3 after the age of 19 years which may influence decisions on their removal or preservation.

Adult↗
PubMed1982

Canine eruption into grafted bone in maxillary alveolar cleft defects.

Forty-six patients with clefts of the alveolus who had received alveolar bone grafts (secondary osteoplasties) at ages 7-14 years, were studied. A total of 64 affected canines from 18 bilateral and 28 unilateral alveolar cleft patients was available. Follow up orthopantomographs were examined to determine the state of root development and spontaneous canine movement through the grafted site. The postoperative observation period ranged from 2-8 years (mean 4.3 +/- 1.5). All test canines erupted through the graft. Spontaneous eruption occurred for 27% of test canines, 17% required surgical uncovering (either bony or soft tissue), and 56% required surgical uncovering and orthodontic assistance to accomplish eruption. All patients required orthodontic treatment to accomplish arch alignment. The prognosis for canine eruption through a graft site is most favorable if the graft is performed at 1/4-1/2 canine root formation and when the patient is aged 9-12 years. The post graft observation period is very important and requires complete cooperation between the orthodontist and the surgeon.

Adolescent↗
PubMed1988

Re- and allotransplantation of teeth--an experimental study in monkeys.

In each of six monkeys one of the permanent lateral incisors with uncompleted root development was replanted. At the same time the contralateral incisors in four of the monkeys were allotransplanted by pairs. The remaining two contralateral incisors served as controls. After 4 weeks and 4 months, respectively, three monkeys were decapitated and the upper lateral incisors with adjacent periodontal tissue were examined histologically. The replanted teeth in five cases had a vital pulp. In the sixth case, however, the replanted incisor exhibited pulpitis and partial necrosis of the pulp. The periodontal membrane had a normal histologic appearance. In two cases a small area of arrested root resorption was observed. With the allotransplanted teeth the histologic appearance was altered. After 4 weeks a pronounced inflammatory reaction was observed in both the pulpal tissue and the periodontal membrane. The pulp was in most cases necrotic, and marked root resorption was observed. Most of the allotransplanted teeth were resorbed and replaced by an irregular hard tissue that resembled osteoid, which in many cases was connected with the tooth remnants by ankylosis. These results indicate that allotransplanted teeth, in contrast to replanted teeth, exhibit the characteristic features of an allograft rejection, including an inflammatory reaction and resorption.

Animals↗
PubMed1990

[Study of dental maturity in children aged 3-16 years in Chengdu].

Dental maturity was studied in a group of 903 healthy children (boys: 465, girls: 438) born in Chengudu from 1972 through 1988. Dental maturity was estimated by the method of Demirjian and Goldstein, which is based on the development of seven left mandibular permanent teeth; teeth formation was studied. The standard and curves of dental maturity for Chengdu children (boys and girls) were constructed. At 3-5 years old, boys had their dental maturity slightly earlier than girls; there was no significant difference between boys and girls (P greater than 0.05). At the age of 7-14, girls were more advanced than boys (P less than 0.05). Developmental curves of seven left mandibular permanent teeth were plotted. The sexual difference was smaller at the crown developmental stage, and it increased during the root development. In all, girls were more advanced by 0.45 year than boys. The maximum average difference was 0.85 year for the canine. The time that each developmental stage has taken was shorter in 50% of girls as compared with that in boys, and it was longer in 28% of girls. There was no difference between boys and girls in the remaining 22% of cases.

Adolescent↗
PubMed1984

Dental root agenesis secondary to irradiation therapy in a case of rhabdomyosarcoma of the middle ear.

There have been only a few published reports on the dental-facial effects of radiation therapy and the subsequent oral management of these patients. A case involving a 13-year-old black male patient with a history of rhabdomyosarcoma is presented. The patient received 4,050 rads of radiation to the right middle ear when he was 2 years of age. His residual medical and dental difficulties are apparently complications from the initial therapy. Examination of the oral cavity revealed bimaxillary micrognathia and marked loss of vertical dimension. A Class II facial profile with Class I molar relationship was observed. The mandible was thin and hypoplastic, with a small knife-edge alveolar ridge. The remaining eighteen erupted permanent teeth were very mobile, and root development had ceased after only initial formation. All of the teeth except the first permanent molars were extracted, and immediate partial dentures were inserted at the time of surgery. A discussion of therapeutic considerations follows the case report.

Abnormalities, Radiation-Induced↗
PubMed1992

The isolation and primary culture of putative human root odontoblasts.

The use of procedures adapted from a routinely successful method of culturing bovine bone has led to the first system for the study of dentinogenesis in vitro. Two types of cells have been grown from pulp obtained from the growing root tips of impacted third molars extracted from 14- to 19-years olds: (1) epithelial-like cells that are probably derived from fragments of the epithelial root sheath and (2) odontoblast-like cells. The cultured epithelial-like cells grow out in distinctive rounded plaques while the odontoblast-like cells are tethered to and/or grow on top of the epithelial-like cells. The odontoblast-like cells produce mineralized matrix by 10 days when cultured on a defined mineralization formula containing conditioned medium obtained from fetal bovine bone cell cultures. Growth factors in this conditioned medium are important to cell proliferation and growth and to the synthesis of mineralized matrix. Sequential enzyme digestion in dispase and dispase/collagenase in serum-free Dulbecco's Modified Eagle's Medium is essential to obtaining adequate cell yields from the apical 3-5 mm of the developing root. Reduction of the number of fibroblasts by treating cultures with dispase in Tyrode's solution midway through the initial growth period enhances the purity of these cell cultures.

Adolescent↗
PubMed1984

[Development of satellite-neuron relations in the spinal ganglia of the rat].

Cerebrospinal ganglia of 11-, 13-, 15-, 18- and 20-day-old embryos have been studied light- and electron-microscopically. On the 11th day of anlage the ganglia are presented exclusively as neuroblasts: the satellite-cells are formed later from lemmoblasts that install into the ganglion on the 13th-15th days both from the surrounding mesenchyme and from the developing roots and trunklets of the cerebrospinal nerves. In the ganglion they undergo proliferation and further differentiation. On the 15th day simple satellite-neuron interrelationships are formed: one satellite-cell is tightly connected with perikaryons of some neuroblasts and young neurons. On the 18th day around some neurons a double layered capsule is formed from the satellite-cells. Multilayered tunics are formed only on the 10th-15th day after birth. During the process of the capsule formation an unusual reactive character of the satellite-neuron interrelationships is revealed, it is manifested as, performed by the satellite-cells, an active microphagocytosis of the perikaryon cytoplasmic processes and the initial segment of the sensitive neuron main process. In embryogenesis the lemmocyte-axon interrelationships develop earlier than the satellite-neuronal ones.

Animals↗
PubMed1984

Four-year longitudinal study of the periodontal health status of overdenture patients.

Seven patients with a total of 12 roots were treated with overdentures (maxillary, mandibular, or both) and recalled at 6-month intervals for a period of 4 years. A periodontist evaluated the periodontal health status of the abutment roots after complete periodontal therapy, immediately prior to placement of the overdentures, and at all recall visits. The gingival tissues around all the abutments were slightly erythematous and edematous and bled on probing. There were no statistically significant changes in pocket depth or in apparent width of attached gingiva on an intra-arch basis. However, statistically significant changes were found on comparison between the maxillary and mandibular arches. Over the 4-year period 50% of the roots remained immobile, 25% of the roots that were initially mobile exhibited no mobility, and 25% of the roots decreased in mobility. Five of 14 roots in eight patients (35.7% of the abutment roots) developed dental caries. Periodic recalls to reinforce plaque control measures, to provide adjunctive periodontal therapy, and to correct and adjust the prostheses of patients treated with overdentures are important factors in the longterm success of this treatment modality. Biomechanically, treatment of patients with overdentures is a valid practical alternative to complete dentures.

Dental Abutments↗