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PubMed2006

Influence of buccal segment size on prevention of side effects from incisor intrusion.

INTRODUCTION: Deep overbite can be corrected by maxillary incisor intrusion. The purpose of this study was to determine whether the size of the maxillary buccal segment influences the amount of steepening, extrusion, or narrowing of the buccal segments, or the rate of intrusion that occurs with maxillary incisor intrusion. METHODS: Twenty patients, 9 to 14 years of age, seeking treatment at a private practice, were divided into 2 groups. Patients in the long buccal-segment group had maxillary buccal segments that included the canines, both premolars, and the first molars. In the short buccal-segment group, the buccal segments consisted of only the maxillary first molars. Patient records were taken at the beginning and end of maxillary incisor intrusion. RESULTS: Intermolar width increased slightly in the short buccal-segment group and decreased slightly in the long buccal-segment group. More steepening of the buccal segment occurred in the short buccal-segment group, and more proclination of the anterior segment in the long buccal-segment group. The size of the buccal segment had no influence on the rate of incisor intrusion or on the amount of buccal-segment extrusion. In both groups, the mean amount of incisor intrusion exceeded 2 mm. CONCLUSIONS: A buccal segment that extends from canine to first molar will help minimize the side effects of incisor intrusion.

Adolescent↗
PubMed2006

Periodontal status of mandibular central incisors after orthodontic proclination in adults.

INTRODUCTION: Some animal and human studies showed that periodontal recession occurs after incisor proclination, but other authors disagree. The purpose of this study was to assess the periodontal status of mandibular central incisors that were proclined during orthodontic treatment. METHODS: The sample comprised 34 adults who had completed treatment over periods of 7 months to 3 years 11 months. The proclination and vertical movement of these teeth were analyzed by 6 measurements from lateral cephalometric radiographs taken before and after treatment. The thickness and height of the symphysis were recorded from pretreatment lateral cephalometric films. Crowding was determined based on the irregularity index from the initial cast. The following periodontal clinical parameters were assessed: plaque and gingival bleeding indexes, probing pocket depth, clinical levels of attachment, and recession of selected teeth and of the mandibular central incisors. The height of the keratinized tissue and the thickness of the facial gingival margin of these incisors were also measured. The Pearson and Spearman correlation analyses, the Fisher exact test, and the Kruskal-Wallis test were applied. RESULTS: Statistical analyses showed no correlation between recession and the plaque and gingival bleeding indexes, probing pocket depth, and total quantity of labial movement (P >.05). Recession was negatively correlated with keratinized gingival height and thickness of the facial gingival margin on the mandibular central incisors. CONCLUSIONS: Final inclination (>95 degrees ) and free gingival-margin thickness (>0.5 mm) showed greater and more severe recession on the mandibular central incisors. Nevertheless, when comparing thickness to the final inclination, thickness had greater relevance to recession.

Adolescent↗
PubMed2004

Distribution and structure of dental enamel in incisors of Tabby mice.

OBJECTIVE: In Tabby mice, the Ta (EDA) gene is mutated. The resulting syndrome is homologous to hypohidrotic ectodermal dysplasia in humans. The Tabby phenotype is characterized by developmental defects of ectodermally derived structures. The teeth show aberrations in number, size and morphology. Dental enamel is a product of specialized epithelial cells, the ameloblasts. It was the aim of the present study to investigate the dental enamel phenotype in Tabby incisors, with emphasis on its distribution and structure. DESIGN: The incisors from five female Tabby and three female wild-type mice were sectioned and ground transversely, etched for 45s with 0.1% nitric acid, sputter-coated with gold-palladium, and observed in SEM. RESULTS: All measured dimensions were more variable in Tabby mice, as was the outline of the enamel-dentin junction. Maxillary incisors were wider in Tabby mice, while mandibular incisors were wider in wild-type mice. No significant difference in enamel thickness was observed. The enamel on the mesial aspect tended to extend further lingually in Tabby incisors in both jaws. On the lateral aspect, this tendency was only significant in mandibular incisors. The enamel-dentin junction often lacked the mesial concavity. Instances of hypoplastic enamel were observed. The complex mouse enamel structure was generally well preserved in Tabby mice, only few instances of aberrant structure were observed. CONCLUSIONS: It is suggested that the reciprocal expression pattern of Ta and Edar (the Ta ligand receptor gene) in outer and inner enamel epithelium, respectively, may influence the position of the enamel-cementum junction.

Animals↗
PubMed1978

Bilateral dens invaginatus in the mandibular incisor region.

A case of bilateral dens invaginatus in the mandibular incisor regions has been reported. Radiographs demonstrated invaginations in both of the incisors in the mandibular incisor region and also demonstrated a periapical radiolucency. Clinical examination revealed two anomalous incisors and apparently there was congenital absence of two mandibular incisors. Dens invaginatus in the mandibular incisors would appear to be a most unusual occurrence.

Adult↗
PubMed1999

Periodontal and pulpal condition of the central incisors after midline osteotomy of the maxilla.

PURPOSE: The purpose of this study was to evaluate the periodontal and pulpal condition of the central incisors after Le Fort I and midline osteotomies for transverse expansion of the maxilla. PATIENTS AND METHODS: The series included 12 women and eight men, with an average age at operation of 28.4 years (range, 17 to 48 years). Each patient, examined retrospectively, underwent transverse expansion of the maxilla by combined Le Fort I and midline osteotomies. The minimum follow-up was 12 months (range, 12 to 85 months, with an average of 38 months). The central incisors were tested for percussion sound, mobility, and pulpal response to electric stimulation, and then compared with the lateral incisors. The pocket depths and the height of the alveolar bone were measured, and the root surface was evaluated for resorption on radiographs. RESULTS: Percussion and mobility tests indicated normal values for all teeth. Four (11%) of the central incisors did not respond to electrical stimulation. There was no difference in pocket depth between the mesial and distal sulci of the central incisors. In one tooth, resorption was detectable on the medial surface of the root. Minor root surface injury was seen in two roots, although these injuries were not progressive. The alveolar bone level of the central incisors was located slightly more superiorly on the mesial than on the distal side. CONCLUSIONS: Although there may be some minor complications to the periodontal and pulpal tissues after combined Le Fort I and midline osteotomies, the harmful effects seem to be of negligible clinical significance.

Adolescent↗
PubMed1993

Normalization of incisor position after adenoidectomy.

Changes in incisor inclination and position in both jaws of children during the first 5 years after adenoidectomy were studied. The main change is a significant increased labial inclination of the incisors for the adenoidectomy groups. All variables that measure the labiolingual position of the mandibular incisors confirm a significant labial incisor positioning for both sexes. Stepwise regression analysis shows that 41% to 44% of the incisor proclination after adenoidectomy is accounted for by two regressors--sex (female) and increase in the sagittal size of the nasopharynx. The study supports the hypothesis that a changed mode of breathing after adenoidectomy is associated with significant labial positioning of the incisor teeth.

Adenoidectomy↗
PubMed1997

Long-term effects of Herbst treatment on the mandibular incisor segment: a cephalometric and biometric investigation.

The purpose of this study was to analyze mandibular incisor changes during and after Herbst treatment with respect to tooth inclination and anterior crowding. The sample consisted of 24 Class II, Division 1 subjects (15 boys and 9 girls) treated with Herbst appliance. Dental casts and lateral head films from before and after treatment, 6 months after treatment and at the end of the growth period (at least 5 years after treatment) were analyzed. During treatment, the lower incisors were proclined (ILi/ML) an average of 10.8 degrees and the incisal edge (li) moved anteriorly by 3.2 mm. The available space and the irregularity index in the lower anterior region were in general unaffected by therapy. During the first posttreatment period of 6 months, the lower incisor inclination (ILi/ML) recovered an average of 7.9 degrees and the incisal edge (li) moved posteriorly by 2.5 mm. However, the available space was almost unchanged. During the second posttreatment period, i.e., from 6 months after treatment to the end of growth, the lower incisor inclination remained on average unchanged in relation to the mandibular plane (ILi/ML) but the teeth retroclined in relation to the nasion-sella line (ILi/NSL). The available space decreased (mean 0.8 mm, p < 0.01) and the irregularity index increased (mean 2.0 mm, p < 0.01). The correlation between changes in the ILi/NSL and in the NSL/ML angles was moderate (r = -0.57, p < 0.01), indicating that the reduction in the ILi/NSL angle was partly a result of anterior mandibular growth rotational changes. In conclusion, it can be said that the proclination of the lower front teeth during Herbst treatment did not result in incisor crowding after treatment. In a long-term perspective, the development of incisor crowding was thought to be associated with normal craniofacial growth changes.

Adolescent↗
PubMed2003

Prevalence and handedness correlates of traumatic injuries to the permanent incisors in 13-17-year-old adolescents in Erzurum, Turkey.

The objectives of the present study were to explore the relationship between dental trauma and handedness, and to assess the prevalence of traumatic injuries to the permanent incisors of 13-17-year-old patients, seeking treatment for various dental conditions in Erzurum, Turkey. A questionnaire focusing on handedness was administered to these patients. Handedness was assessed by the Edinburgh Handedness Inventory (Oldfield, 1971). Hand preference was divided into two classes for convenience in data analysis: (i) right-handers (GSc from 80 to 100); and (ii) left-handers (GSc from -80 to -100). This study included the 13-17-year-old group patients who had GSc as described above. Thus, the present study was carried out on 2180 (1252 male and 928 female, with a mean age of 14.9 years) out of 2392 patients. The clinical examinations and radiographic assessments were performed in full-designed dental chairs. Preliminary analysis showed no differences in rates of handedness with respect to sex and age. Overall, 10.4% of the patients were left-handers. A total of 292 (13.4%) of 2180 patients examined had one or more traumatized permanent incisors. The proportion of dental trauma was significantly higher in males than in females, 17.41% in males as compared to 7.97% in females; and ratio of the affected males to females was about 2.18. Sex difference in the prevalence of traumatized permanent incisors was statistically significant (P < 0.001). That is, males had a significantly higher risk of dental trauma than females (P < 0.001; odds ratio: 2.49; 95% confidence interval (CI) 1.88, 3.23). There was a higher level of traumatized permanent incisors among left-handers than among right-handers. 28.3% of left-handers and 11.7% of right-handers had dental trauma. This difference in the prevalence of traumatized permanent incisors for handedness was statistically significant (P < 0.001). Indeed, left-handers had a significantly higher risk on dental trauma than right-handers (P < 0.001; odds ratio: 3.09; 95% CI 2.23, 4.29). The primary causative factor in the occurrence of trauma was the fall (27.7%). Then came violence and fight as the second most frequent cause of trauma (24%), followed by sports injury (18.8%). Trauma resulting from collisions and traffic accidents were accounted as 13.7 and 11.3% of all cases, respectively. The other causes were 4.5%. In conclusion, the present study suggests that left-handed adolescents have more frequent permanent incisor tooth trauma than right-handed adolescents. Left-handedness, therefore, appears to be a risk factor for trauma in 13-17-year-old adolescents.

Adolescent↗
PubMed2003

Clinical outcomes for permanent incisor luxations in a pediatric population. I. Intrusions.

A longitudinal outcome study was undertaken to identify variables that significantly influenced tooth survival as well as pulpal and periodontal outcomes for intruded permanent maxillary incisors of children and adolescents. All cases were treated between June 1988 and June 1998 in a teaching hospital clinic. Clinical and radiographic data were collected for 26 patients (19 males, 7 females) that represented 31 permanent maxillary incisors. Mean age at the time of injury was 9.3 years (range = 5.5-17.8 years). Mean time elapsed to follow up was 1380 days (range = 65-3394 days). Survival analysis was used to identify variables significantly related to the survival and pulp necrosis (PN) for these incisors. Proportional hazards regression yielded significant prognostic models for tooth survival and the diagnosis of PN (P < 0.05). Incisors intruded > 6 mm had significantly decreased survival compared with incisors intruded < 3 mm (5-year survival, 0.45 and 1.0, respectively, (P < 0.05)). Complex crown fractures were significantly related to the development of PN (P < 0.05). Logistic regression analysis showed that treatment method and severity of intrusion were related to the presence of replacement root resorption (P < 0.05). This study represents the largest sample of intruded permanent incisors examined in an outcome study of children and adolescents exclusively.

Adolescent↗
PubMed1990

Stability of mandibular incisors following excessive proclination: a study in adults with surgically treated mandibular prognathism.

The purpose of this study was to determine if mandibular incisors could be proclined markedly without increasing the potential for relapse of crowding. Patients with surgically treated mandibular prognathism were selected. In 29 patients the mandibular incisors were proclined more than 10 degrees during the presurgical orthodontic phase. The remaining 33 patients had only minimal change in incisor inclination. A long-term follow-up examination was performed 10.0 (SD 2.3) and 11.1 (SD 3.1) years postoperatively in 26 and 24 patients, respectively. Study casts were measured before and after treatment, three years after surgery, and long-term. Cephalograms were evaluated before and after treatment, immediately before and after surgery, and three years after surgery. Prior to therapy the patients treated with presurgical proclination had less dental arch length and more retroclined and crowded mandibular incisors than the patients in the other group. No differences in parameters were observed at later intervals. Dental arch length and intercanine width decreased and incisor irregularity increased in both groups during the follow-up periods. No intergroup differences in changes were observed. Indications for proclination of mandibular incisors are discussed.

Adult↗
PubMed1997

Analysis of fused maxillary incisor dentition in p53-deficient exencephalic mice.

Out of a total of 21 exencephalic p53-deficient embryonic and newborn mice, 6 (28.6%) possessed fused maxillary incisor teeth. On histological analysis of the 5 examples seen on day 19.5 of gestation and newborn mice, 3 varieties were observed: an example of 'simple' fusion, 3 examples of simple fusion each of which contained a 'dens in dente' ('tooth within a tooth'), and a single example in which the fused teeth were associated with a median supernumerary incisor tooth which, while deeply indenting the labial surface of the fused teeth, was in all locations a completely separate unit. 3-D reconstructions of the fused teeth demonstrated that they were all of the fusio subtotalis variety. No gross abnormalities were observed in the other dentition in these mice. It is noted that in mice fused maxillary incisor teeth are relatively commonly associated with both hypervitaminosis A-induced and trypan blue-induced exencephaly. It is believed that the presence of dens in dente within fused maxillary incisor teeth has only once been reported in mice, and the association between fused maxillary incisor teeth and a median supernumerary incisor tooth has not previously been reported in this species.

Animals↗
PubMed2001

Deciduous canine and permanent lateral incisor differential root resorption.

When a permanent maxillary canine erupts apical to the permanent lateral incisor and the deciduous canine, resorption typically takes place only on the deciduous canine root. An understanding of this differential resorption could provide insight into the reasons for excessive iatrogenic root resorption during orthodontic tooth movement. The purpose of the present study was to examine the response of roots of permanent lateral incisors and deciduous canines to simulated resorption, and to acid and enzyme attack, reflecting the physiologic environment of an erupting permanent canine. Groups of maxillary permanent lateral incisor and deciduous canine roots were exposed to 5 combinations of Ten Cate demineralizing solution, Ten Cate demineralizing solution with EDTA, and a Type I collagenase solution. Sections of the roots were examined under a polarized light microscope. Analysis of variation of the resulting root lesions demonstrated that the lesion depths for deciduous canines were greater than those for permanent lateral incisors when averaged across 4 of the conditions (F(1,24) = 7.49, P =.0115). On average, deciduous canine roots demonstrated lesions 10% deeper than did permanent lateral incisor roots. We concluded that when deciduous canine and permanent lateral incisor roots are subjected to acid and enzyme attack, reflecting the physiologic environment of an erupting permanent canine, significantly deeper demineralized lesions are seen in the deciduous roots compared with the permanent roots. This finding may partially explain the differential root resorption during permanent tooth eruption.

Acids↗
PubMed2002

Closed-eruption surgical technique for impacted maxillary incisors: a postorthodontic periodontal evaluation.

The aim of this study was to evaluate the clinical appearance and pulpal and periodontal status of impacted maxillary central incisors that had been exposed and aligned after a closed-eruption surgical technique. Twenty-one patients were examined 4.5 years (median) postretention. The treated central incisors showed no significant differences in plaque and gingival indexes, widths of attached gingiva, and crown lengths, whereas a small, but statistically significant, increase was found in the mean pocket depth compared with the contralateral incisors. The bone support was reduced by 5% to 6% in the treated teeth, and, in one third of the cases, an abnormal gingival contour was recorded. The lateral incisors revealed similar plaque and gingival indexes and pocket depths on each side, but the lateral incisors immediately adjacent to the treated tooth showed decreased widths of keratinized gingiva and increased crown lengths. Even though statistically significant differences were found in some of the periodontal parameters measured, the overall clinical consequences of a conservative exposure and orthodontic alignment of impacted incisors by the closed-eruption technique are minimal.

Adolescent↗
PubMed2002

Nonprosthodontic management of alveolar clefts with 2 incisors missing on the cleft side: a report of 5 patients.

A treatment combining autotransplantation of developing premolars and orthodontic space closure is described as an alternative to prosthodontics in the management of patients with alveolar clefts when 2 cleft-side incisors are missing. We report on 5 consecutive patients with unilateral clefts in whom 2 cleft-side incisors were congenitally missing, severely malformed, ectopically erupting, or lost because of trauma. In each instance, a mandibular premolar with a partly developed root was transplanted to the central incisor region (3 patients had previously undergone alveolar bone grafting). Root growth continued in all transplants. After an observation period of 2 years 6 months to 7 years 8 months, all transplanted teeth were present and fulfilled the established success criteria. The physiologic status of the transplanted premolars compared favorably with that of the central incisor on the noncleft side. The appearance of the reshaped transplants was found to match the noncleft incisor in 3 patients and deviated somewhat in 2. We concluded that an acceptable clinical outcome can be obtained by tooth transplantation combined with orthodontic space closure in patients with alveolar clefts and 2 missing cleft-side incisors.

Adolescent↗
PubMed2003

Peg-shaped and small lateral incisors not at higher risk for root resorption.

The purpose of this study was to examine the pattern of external root resorption for peg-shaped and small lateral incisors according to various conditions and to compare it with that of normal-shaped lateral incisors. The periapical radiographs of 114 patients with 60 peg-shaped and 54 small lateral incisors were measured before and after treatment. Crown shape was assessed by examining pretreatment study casts. Findings showed that there was no significant difference in external root resorption between peg-shaped (1.09 mm) and normal lateral incisors (0.88 mm). However, a statistically significant difference in apical root resorption between small lateral incisors (1.03 mm) and normal lateral incisors (1.62 mm) was found. Peg-shaped laterals were also coincidentally found to occur more frequently on the left side of the arch.

Adolescent↗
PubMed1993

Biometric analysis of the dental casts of Maasai following traditional extraction of mandibular permanent central incisors and of Kikuyu children.

Dental plaster casts of 93 Maasai and 79 Kikuyu children age 12-15 years were analysed. Four biometric measurements were taken of the maxillary and mandibular casts: intercanine distance (C-C), inter-molar distance (M-M), canine arch circumference (C-C ACirc.), and molar arch circumference (M-M ACirc.). Incisor space (IS) was also measured in the mandibular casts. The mean values of all measurements except (M-M) in the mandibular casts were significantly reduced in the Maasai who had permanent central incisors extracted compared to the non-extracted Maasai and the Kikuyu. The mean incisor space in the Maasai with extractions was 6.3 mm compared to 11.7 mm in the non-extracted Maasai group. The extent of reduction of IS, C-C, C-C ACirc. and M-M ACirc. following extractions of the incisors may depend on the mesial drift of lateral incisors, jaw growth and soft tissue influence. The position of the tongue and occlusal relationship of the molars may prevent bucco-lingual movements maintaining a constant M-M. There was no significant difference in the mandibular cast dimensions of the non-extracted Maasai and the Kikuyu. Analysis of the maxillary cast dimensions of the Maasai with extraction, non-extracted Maasai and Kikuyu showed no significant differences suggesting that the extraction of mandibular incisors has no effect on maxillary arch dimensions. The variability in growth of the dento-alveolar complex itself may explain why the dental arch dimensions are similar in the Maasai and Kikuyu despite ethnic differences. There was no significant difference between the male and female dental arch dimensions.

Adolescent↗
PubMed2003

Periodontal status following surgical-orthodontic alignment of impacted central incisors with an open-eruption technique.

Several factors may affect the outcome of the orthodontic/surgical modality for the resolution of impacted central incisors, but particularly the manner in which the impacted tooth is exposed. The present study aimed to evaluate the post-retention clinical appearance and periodontal status of impacted maxillary central incisors which were exposed and aligned with an open-eruption surgical-orthodontic technique. Twelve subjects (four males, eight females), aged 22 years (range 15-38 years), previously treated for a unilateral impacted central incisor (ICI), were examined 10 years (range 3-25 years) post-retention. A split-mouth method was used for the comparison with the unaffected side. One treated central incisor exfoliated 10 years post-retention, thus the results were based on the remaining 11 patients. Statistically significant differences were found between the affected and control incisors in most of the periodontal parameters measured, although some were small and of minimal clinical importance. The increase in the mesio-labial pocket depth was associated with a highly significant 10 per cent reduction in bone level at this site (P = 0.007). A highly statistically significant increase in crown length (P < 0.001) and a reduction in the width of the attached gingiva (P = 0.005) were seen in these previously impacted teeth. An abnormal gingival contour was present in eight treated incisors and positional relapse in five cases. It is concluded that the convenience of the open-eruption technique must be weighed against the long-term negative aesthetic and periodontal effects on the treated tooth, although the findings of this study should be viewed with caution due to the limited sample size.

Adolescent↗
PubMed2007

A radiographic analysis of external apical root resorption of maxillary incisors during active orthodontic treatment.

External apical root resorption (EARR) is an undesirable consequence of orthodontic treatment. The purpose of this study was to measure the amount of EARR and to examine its clinical significance in maxillary incisors, during a 12-month active treatment period. A further aim was to examine the contribution of gender, treatment technique, treatment duration, and extraction of maxillary first premolars to EARR. The sample comprised 151 maxillary incisor teeth in 40 patients (16 males, 24 females) aged 12-22 years, with different malocclusions. Standard periapical radiographs, using the long-cone paralleling technique, were obtained before and 6 and 12 months after the start of treatment. Quantitative measurements for 80 central and 71 lateral maxillary incisors were performed separately and corrected for image distortion. Root length reduction was calculated in millimetres and in terms of the percentage of the original root length. Resorption of more than 1 mm at 12 months of active treatment was considered to be clinically significant. On average, the degree of EARR for the maxillary central incisors was 0.77 +/- 0.42 and 1.67 +/- 0.64 mm, respectively, during the 6- and 12-month follow-up (P < 0.001). For the lateral incisors, the degree of EARR was 0.88 +/- 0.51 and 1.79 +/- 0.66 mm, respectively (P < 0.001). Clinically significant resorption was found for 74 per cent of the centrals and 82 per cent of the laterals. No significant correlation was observed between EARR and treatment technique. EARR was found to be correlated with gender for the lateral incisors. The effect of treatment duration (P < 0.001) and premolar extraction (P < 0.001) was statistically significant for both tooth groups.

Adolescent↗