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PubMed1980

A time-related study of periodontal healing and root resorption activity after replantation of mature permanent incisors in monkeys.

Periodontal and pulpal healing was registered histometrically at different observation periods after replantation of mature incisors in green Vervet monkeys. Maxillary central incisors and mandibular lateral incisors were extracted and then replanted after either 0- to 18 min. In the 18 min. group, the teeth were stored dry prior to replantation. The animals were sacrificed 1-, 2-, 4-, or 8 weeks after replantation. The mobility of the replanted teeth was determined and histological examination carried out. The following parameters were registered for each tooth: periodontal ligament healing, surface resorption, inflammatory resorption, replacement resorption (ankylosis) and the extent of vital pulp. Periodontal ligament healing, as assessed histologically or via mobility testing, was almost complete 2--4 weeks after replantation. Surface resorption was first recognized after 1 week and became prominent after 2 weeks; the frequency increased slightly after 4- and 8 weeks. Inflammatory resorption was first recognized after 1 week and showed a rapid extension with increasing observation periods. Replacement resorption was first noted afer 2 weeks, where the peak frequency occurred. The frequency decreased in both groups with increased observation periods. The 18 min. group showed significantly more replacement and inflammatory resorption than the immediate replantation group. Finally, an analysis of the systematic error of histometric registration of root resorption showed that the uneven distribution of root resorption upon the root surface could lead to significant errors in the registration of root resorption activity unless a proper sectioning plane was chosen and an adequate number of measuring locations along the root surface was used.

Animals↗
PubMed1982

The labio-lingual position of the lower incisors in individuals with ideal occlusion. A study on medieval skulls.

In a sample of 73 Norwegian medieval skulls with ideal, occlusion measurements were taken directly on the dental arches and on lateral cephalograms. The configuration of the lower face and the position of the incisors were different from modern Norwegian adults. Consequently the material could be used to verify a linear relationship between the position of the lower incisors and some guiding variables. The principles of a guiding multiple linear equation as used in the Bergen cephalometric analysis was confirmed. Further, it was shown that the group of guiding variables related to the position of the lower incisors could be extended by introducing dental arch dimensions.

Adult↗
PubMed1981

[Reaction of the rat submandibular gland to repeated amputations of the lower and upper incisors (a morphometric study)].

It has been stated in experiments performed on Wister rats, that periodic amputation both of lower and upper incisor teeth results in hypertrophy of the submandibular salivary glands. However, when the upper incisors are extirpated, the enlargement of the gland is less pronounced, especially in the males. The leading role in the reaction plays the increasing size of the acinar cells, but certain ductal elements (especially striated ducts) also react by increasing their diameter in response to the trauma both in the lower and upper incisors.

Amputation, Traumatic↗
PubMed1981

The arrangement of ameloblasts on the surface of maturing enamel of the rat incisor tooth.

The location of striated border cells versus non-striated border cells during enamel maturation in the rat incisor was studied by light microscopy. Serial cross sections of the lower incisors were examined from a segment of the incisor in sections which also included the first molar tooth. In the series recorded here every cross section showed both striated and non-striated border cells. A map showing the distribution of cells on the enamel surface, as plotted from their position in each of the cross sections, reveals that the non-striated border cells traverse the enamel as oblique bands. Between the narrow bands of non-striated border cells were wide bands of striated border cells. The non-striated border cells were joined at their basal nuclear poles by contacts which appeared to separate the lateral inter-ameloblast space from the space between the papillary-ridge cells. Neither the striated border cells nor the non-striated border cells went entirely to the edge of the enamel organs. The above pattern of striated border cells and non-striated border cells is regarded to be a manifestation of the cyclical activity of maturation ameloblasts.

Ameloblasts↗
PubMed1980

Noncollagenous proteins of dentin. A re-examination of proteins from rat incisor dentin utilizing techniques to avoid artifacts.

Noncollagenous proteins (NCPs) were obtained rrom rat dentin using several precautionary measures to prevent artifactual degradation and losses of the proteins. Prior to demineralization, rat incisor dentin was extracted with 4 M guanidine hydrochloride (GdmCl) containing enzyme inhibitors. The only major component extracted with GdmCl was a proteoglycan fraction. Most of the NCPs were extracted when the incisors were decalcified with an EDTA solution containing protease inhibitors. The EDTA extract contained four types of macromolecules: acidic glycoproteins, gamma-carboxyglutamic acid (Gla)-containing proteins, phosphoproteins, and proteoglycans. With two exceptions, the apparent molecular weights of these NCPs were greater than 50,000. Our observations contrast sharply with the results obtained by others for human dentin NCPs and suggest that artifactual degradation and losses of some NCPs occurred in these previous studies. The organic phosphate-containing fraction was biphasic when the EDTA extract was chromatographed on DEAE-cellulose. Rechromatography of this fraction by two different procedures separated the material into a complex glycoprotein-containing fraction and, a single rat incisor phosphoprotein peak (RIP). Thus, the earlier interpretation by others that the biphasic nature of the RIP-containing fraction represents two widely differing phosphoprotein species was premature. Highly purified RIP, prepared by passage through a sulfonated polystyrene column, contained no cysteine, valine, methionine, leucine, phenylalanine, or arginine, and the level of phosphoseryl residues was higher than for any previous report. When this preparation of phosphoprotein was dephosphorylated (dP-RIP) and rechromatographed on DEAE-cellulose, a partial separation into two fractions was observed. Automated Edman degradation of fraction dP-RIP suggested the presence of two NH2-terminal sequences: Asp-Asp-Asp-Asn and Asp-Asp-Pro-Asn. However, this material displayed a single protein band when applied to 7.5% sodium dodecyl sulfate polyacrylamide gel electrophoresis and stained with Coomassie brilliant blue. The apparent molecular weight of dP-RIP, compared to standard globular proteins, was about 72,000. The data suggest that rat dentin contains at least two major molecular species of RIP that are closely related in size and-structure. In addition, preliminary evidence suggested that other minor forms of related phosphoproteins may exist.

Amino Acid Sequence↗
PubMed1995

[Hypodontia: considerations on orthodontic therapy in agenesis of the permanent upper lateral incisor].

The authors have investigated different clinical cases having in common the agenesis of the permanent upper lateral incisors, to evaluate from a clinical and esthetic point of view the possibilities, results and the limits of the orthodontic treatment. These are nowadays increasingly associated with esthetic dentistry, prosthodontics, implantology and finally with dental transplantation. The patients presented the absence of one or both permanent upper lateral incisors or the agenesis of other teeth, sometimes associated with dental crowding or a not favourable intermaxillary relation. Most of the cases were treated with compensatory extraction of the other normal or hypoplastic permanent upper lateral incisor. The results were satisfactory but the mean treatment time was relatively long (56 months, including the retention phase), according to the difficulty of obtaining a good esthetic result in the smile line. The importance of a correct point of time of the interception for the choice of the most adequate therapy is emphasized. The possibility of correcting occlusal relation by means of the orthopedic treatment of the maxillary structures is limited to the end of the deciduous dentition. The diagnostic criteria for a correct and opportune interception of this anomaly are being stressed on. Finally the esthetic problems arising of the orthodontic space closure and the possible solutions were discussed.

Adolescent↗
PubMedDate not supplied

Premature loss of the maxillary primary incisors: effect on speech production.

The residual effect of premature loss due to extraction of the four maxillary primary incisors on speech production was studied. The articulation of twenty-six subjects who had their teeth extracted before the age of five years was evaluated at eight, nine, or ten years old and compared with the articulation of an age-matched comparison group with normal exfoliation of their incisors. T-tests for related measures revealed no statistically significant differences between the group with premature loss and the comparison group. These results suggest that loss of maxillary incisors in children younger than five years is not likely to result in defective articulation while the teeth are missing or when the permanent dentition is acquired.

Articulation Disorders↗
PubMed1995

Current controversies in late incisor crowding.

Although the terminology is mildly controversial, late incisor crowding (tertiary crowding, late secondary crowding, post-adolescent crowding) is widely regarded as a normal maturation event which is likely to affect most individuals to some extent. Disagreement arises when attempts are made to quantify the change and to predict the timing of the crowding. Most young adults experience some degree of loss of incisor alignment, usually near the anticipated emergence time for the third molars, and almost characteristically it is the lower anterior teeth which best demonstrate the phenomenon. Unfortunately, the physiological crowding changes are frequently confused with orthodontic treatment relapse. Greater controversy surrounds the aetiology of the undesirable crowding changes and despite many attempts we are still not in the enlightened position of explaining, predicting or preventing the problem (except by permanent retention). It is illogical to assume a single cause as the beguilingly simple observation of crowding belies the complexity of possible interacting factors. Perhaps it is a capricious combination of: tooth size and arch form; facial growth pattern (differential soft tissue and skeletal maturation); continuing late growth rotations; cumulative effects of resting, functional and parafunctional soft tissue pressures; lack of compensating attrition; and an ill-defined, mesially acting force emanating from the back of the dental arch. Many theories have attempted to resolve the mystery of the mesially acting force, including: pressure from erupting third molars; an inherent mesial migration; continuing mesial and occlusal dental drifting; maturation and contraction of periodontal soft tissues (particularly the transseptal fibres); the anterior component of occlusal forces; and the lower anterior arch contracting influence of the incisor overbite.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Autotransplantation of 45 teeth to the upper incisor region in adolescents.

Young, growing individuals with one or more upper incisors missing due to trauma, agenesis or extraction of abnormal teeth can be treated with autotransplantation to restore aesthetics and function and to preserve the volume of the alveolar process. Studies have been performed to evaluate the prognosis, indicating a good prognosis, especially if an immature transplant is available, developed to 3/4 of the full root length. The purpose of this study was to analyse the result of all autotransplantation of teeth performed to the upper incisor region between 1979 and 1990 at the Department of Oral Surgery, Eastmaninstitutet, Stockholm, Sweden. The material consists of 23 immature and 22 mature teeth in 40 patients with a mean age of 12 years. They were systematically followed up clinically and roentgenologically for up to four years after surgery. 22 of the 23 immature (96%) and 18 of the 22 mature teeth (82%) were observed to be without serious complications. The complications occurred, with one exception, within the first year of observation. The conclusion drawn from this study is that autotransplantation to the upper incisor region can be performed with a good prognosis, both for mature and immature teeth.

Adolescent↗
PubMed1993

Multiple developmental origin of the upper incisor in mouse: histological and computer assisted 3-D-reconstruction studies.

Heads of 11-15-day-old mouse embryos were cut in frontal serial sections. Early development of the maxillary incisor was analyzed using series of thick (5 and 7 microns) and semi-thin (1 micron) frontal sections and computer assisted 3-D-reconstructions of the epithelial component. The enamel organ of the mouse maxillary incisor was found to be a complex structure of multiple origin, involving several epithelial anlagen--primary dental laminae--, which could hypothetically correspond to the 5 upper incisors of early mammals. The transitory existence of at once distinct and then fusing dental primordia could reflect heterochronic changes in ontogeny which might be related to phyletic trends.

Animals↗
PubMed1995

Orthodontic management of a horizontally positioned maxillary lateral incisor.

A case report of a patient who had lost her maxillary permanent left central incisor, left cuspid and left first premolar teeth due to a cyst operation, is presented. The maxillary permanent left lateral incisor was in horizontal position high in the vestibule. She was treated with removable and fixed orthodontic appliances. The lateral incisor was uprighted and brought into its normal position in the dental arch. For aesthetics and function missing teeth were replaced with a specially designed prosthesis.

Child↗
PubMedDate not supplied

Management of lower incisor crowding in the early mixed dentition.

This paper describes normal and problem development in lower incisor positioning and offers options for management of crowded cases. The following guidelines were recommended, (1) lower incisor crowding of 2 mm or less and with an intercanine width greater than 28mm will usually resolve spontaneously, (2) lower incisor crowding of 3-4 mm is best managed by discing of the primary dentition, (3) crowding assessment of 5-9 mm requires extraction of primary teeth with probable placement of a supportive lingual arch and, (4) crowding greater than 10 mm requires fixed appliance therapy and careful orthodontic management with attention to the severity of the malocclusion.

Cephalometry↗
PubMed1996

Dental trauma: 4. Avulsion and replantation of immature incisor teeth.

Facial trauma in children with immature incisor teeth often results in the complete avulsion of a maxillary permanent incisor because the root is only partially formed and the alveolar bone is still elastic. These teeth may be replanted: the long-term prognosis for replanted incisors has greatly improved because of improvements in our clinical knowledge following the pioneering and painstaking research work of Andreasen and his colleagues.

Adolescent↗
PubMed1996

Ameloblastin expression in rat incisors and human tooth germs.

We recently identified ameloblastin as an ameloblast-specific gene product from a rat incisor cDNA library (Krebsbach et al., J. Biol. Chem. 271: 4431-4435, 1996). Here we report the developmental pattern of expression of ameloblastin in rat incisors and human tooth germs as visualized by in situ hybridization and immunochemistry. Compared to the expression of amelogenin, the major ameloblast product, ameloblastin mRNA was more widely expressed in ameloblasts from the presecretory to the late maturation stage of development. Ameloblastin mRNA was first observed in the juxtanuclear cytoplasm or presecretory stage ameloblasts, gradually increased in the distal cytoplasm of secretory stage ameloblasts and was found throughout the cytoplasm of early to late maturation stage ameloblasts. The immunostaining of ameloblastin, using a monospecific antibody raised against a recombinant protein, showed intense reactivity in Tomes' processes of secretory stage ameloblasts and surrounding enamel. The immunoreaction was concentrated in the juxtanuclear cytoplasm of late maturation stage ameloblasts. High-resolution colloidal gold immunocytochemistry established the presence of ameloblastin antigenicity in the Golgi apparatus, secretory granules in Tomes' process and enamel. Human tooth germs in early to late bell stage also expressed ameloblastin mRNA and ameloblastin antigenicity in the ameloblasts. Western blot analysis of protein extracts from rat incisor tissues indicated that ameloblastin can be found in the enamel epithelial tissue and in mineralized enamel, as well as in the EDTA decalcification solution. These data indicate that ameloblastin is an ameloblast secretory product which is sequentially expressed from the presecretory to the late maturation stage in rat and human teeth. This unique developmental pattern suggests that ameloblastin may have a broader role in amelogenesis than amelogenin and tuftelin.

Ameloblasts↗
PubMed1996

Impaction of a mandibular permanent lateral incisor associated with fused primary teeth: a case report.

Although anesthetic and functional problems created by fused primary teeth are relatively transient, occlusal development should be monitored to prevent abnormal delays in the eruption of the permanent successors. This report describes an unusual case in which horizontal impaction of the permanent mandibular left lateral incisor was associated with fusion of the primary mandibular left lateral incisor and canine. After the fused primary tooth was extracted, the impacted lateral incisor was able to erupt without the aid of orthodontic forces. Early detection eliminated the need for surgical intervention at a later stage.

Child↗
PubMed1997

Surgical management of a labially placed permanent maxillary central incisor after supernumerary tooth extraction: report of a case.

A case of a 12-year old-boy having a chief complaint of labially placed maxillary central incisor is presented. Radiographic evaluation revealed the presence of a supernumerary tooth impeding the eruption of the left permanent central incisor. The mesiodens was surgically removed and the permanent central incisor was positioned and splinted into proper alignment.

Child↗
PubMed1997

Profile changes associated with maxillary incisor retraction in the postadolescent orthodontic patient.

Maxillary incisor retraction and associated upper lip changes were studied in 30 male and 30 female postadolescent orthodontic patients to determine if a statistically significant correlation and ratio existed between maxillary incisor and lip retraction, dependent on thickness, strain, and length of the upper lip. This analysis attempted to eliminate the effects of growth and gender. Statistically significant correlations were found in both male and female patients who had thin, highly strained lips. Although a ratio for predictive purposes was determined for each of these groups, their absolute value is questionable because no apparent pattern exists between them. Furthermore, as lip thickness increased and lip strain decreased, correlation coefficients fell to nonsignificance, making it more difficult to predict upper lip change resulting from maxillary incisor retraction in these individuals.

Adult↗
PubMed1998

Stability of mandibular incisor decompensation in orthognathic patients.

This retrospective cephalometric study examined the stability of mandibular incisor decompensation following orthognathic treatment. It also studied the relationship between the mandibular incisor-mandibular plane angle (LIMnp) and the maxillary-mandibular planes angle (MMA). Two groups of 22 subjects each underwent either mandibular advancement only or bimaxillary surgery with mandibular setback. Serial radiographs of each subject were digitized. Twenty-seven Class I subjects who were part of the Leighton Growth Study served as the control. The control group showed a significant association between LIMnp and MMA. For the surgical groups, the only significant relationship between LIMnp and MMA was seen in the mandibular advancement group at debond. No definite indicator was found to suggest that the final MMA dictates the amount of mandibular incisor relapse following debond. Only the bimaxillary group showed an association between changes in LIMnp and changes in MMA during the review period.

Adult↗