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PubMed2006

[The compensation of post-treatment incisor torque in sagittal jaw relationship].

OBJECTIVE: To investigate the dental compensation in different sagittal jaw relationships. METHODS: One hundred and fifty-seven post-treatment cases with satisfied outcome were chosen. Computerized cephalometric analysis was performed to evaluate the sagittal jaw relationship. Incisor torque were measured based on study models. Correlation analysis was performed. RESULTS: Compared with skeletal class I cases, the upper incisors of skeletal class III cases were more proclined, and lower incisors were more retroclined; the opposite result was found in skeletal class II cases. Dental compensation in class I cases took place primarily at lower incisors. CONCLUSIONS: Incisor torque control was important in patients with various sagittal jaw relationships.

Cephalometry↗
PubMed2006

The prevalence and pattern of hypodontia of the permanent teeth and crown size and shape deformity affecting upper lateral incisors in a sample of Jordanian dental patients.

OBJECTIVE: The aim of this study was to determine the prevalence and pattern of hypodontia and the extent of congenital malformation in the permanent teeth of a sample of Jordanian adults. MATERIAL AND METHODS: Clinical examinations were carried out on 1045 dental patients aged 16 to 45 years to record any congenital absence of teeth except 3rd molars and to note any crown shape or size deformities affecting the upper lateral incisor. The congenital absence of permanent teeth was confirmed by taking complete dental history and orthopantomograms. Impacted teeth and teeth lost as a consequence of extraction or trauma were recorded as present. RESULTS: The prevalence of hypodontia was found to be 5.5% of the sample and the lower second premolar was the most frequently missing tooth. The number of missing upper lateral incisors was significantly higher than that of lower lateral incisors, (p < 0.05). Peg-shaped and reduced size upper lateral incisors were observed in 2.3% and 2.9% of the sample respectively. There were no significant differences according to gender, location of tooth according to arch or side of the jaw and hypodontic pattern. CONCLUSION: The prevalence of hypodontia was 5.5%, that of peg-shaped lateral incisor was 2.3% and that of reduced crown size was 2.9%.

Adolescent↗
PubMed1991

Incisor growth acceleration after lesions in the lateral pontine reticular formation of rats.

The length of upper and lower incisors of Long-Evans hooded rats between gingiva and top were measured before and after small bilateral symmetric electrolytic lesions of the pontine reticular formation between the ventromedial parabrachial nucleus and the motor trigeminal nucleus. Ten days after lesions of this region 8.5 mm posterior to bregma the length of upper incisors was 13.4 +/- 0.7 mm compared with 6.1 +/- 0.2 mm before lesion (p less than 0.01) and the length of the lower incisors 17.1 +/- 0.4 mm compared with 10.2 +/- 0.2 mm before lesion (p less than 0.01). A second group with a smaller lesion of this region 9.0 mm posterior to bregma reached upper incisor length of 13.2 +/- 0.4 mm (p less than 0.05) and lower incisor length of 14.7 +/- 0.5 mm (p less than 0.05) at the 20th postoperative day. Sham-operated controls had no tooth growth acceleration.

Animals↗
PubMed1990

Eruptive changes in the axial inclination of lower incisor teeth--a longitudinal study.

A longitudinal cephalometric study investigated the change in lower incisor inclination in a group of 32 subjects over a period from 5-10 years of age, with yearly cephalometric radiographs and 6 monthly study models. In a previous study, it was shown that in all of these subjects, the lower incisors became more proclined over this 5 year period. Changes in the rate of proclination of the lower incisors over this period were studied, and this was related to events such as eruption, and contact with the upper incisors or palatal mucosa where this occurred. The association between the inclination of lower incisors before and just after eruption, and their "final" inclination was investigated, and the possible explanations and implications of the findings are discussed.

Child↗
PubMed1989

[Two case reports of extraction with the upper central incisors].

Although extraction of the upper central incisors is very rare because of their esthetical importance, they are sometimes extracted when impaction, root resorption, abnormal morphology, severe caries and/or trauma are involved. When extracted, tooth size adjustment, crown-bridge and/or orthodontic treatment are proposed for functional and/or esthetic improvement. Two present cases were reported of Angle class I crowding with root resorption of the upper central incisors caused by apical abscess (case 1) and impacted canines (case 2). The above central incisors were extracted and orthodontic tooth alignment was performed on both cases prior to final occlusal adjustment. Problems we encountered in through these cases were tooth size ratio between the upper and lower teeth causing spacing arch and/or disharmony of occlusion. In case 1, edge to edge anterior relationship was established because the over-all tooth ratio was 93.30% which was out side one standard deviation although the upper lateral incisors were tipped mesially to create some spaces. The over-all tooth ratio in case 2, however, was 92.13% which was inside one standard deviation and normal occlusion was restored. It is suggested that final tooth size adjustment is necessary for good occlusion in extraction cases of upper central incisors.

Adolescent↗
PubMed1989

[Clinical study of ectopic eruption of permanent incisors and first molars].

UNLABELLED: Using the X-ray films, plastic models and pathological photograph of 4824 patients seen at the Department of Pedodontics of Iwate Medical University, the patterns of ectopic eruptions of permanent incisors and first molars (restricted to these teeth in this study) were classified into 4 groups (I-IV) to investigate the conditions of its incidence, size of the teeth and dental arch, and conditions at the stage of the mixed and permanent dentitions. RESULTS: 1. The total frequency of ectopic eruptions was 5.6%. No difference based on sex was found. 2. By classification, ectopic eruptions of the upper and lower permanent central incisors (Group I) amounted to more than half of the total frequency. The incidence of ectopic eruptions of the upper and lower permanent first molars (Group III) was very low and amounted to only 4.6% of the total frequency. 3. In Groups I and III, the incidence was higher in the maxilla than in the mandible. 4. Based on sex, the incidence was higher in boys in Group III and in girls in group II. 5. Ectopia of the permanent central incisors was frequently bilateral and those of the lower permanent lateral incisors and upper permanent first molars were frequently unilateral. 6. The mesiodistal width of the ectopically erupted permanent teeth tended to be somewhat enlarged, but showed no significant differences from Ono's mean value. 7. In ectopic eruptions at the area of the incisors, the C-C distance was narrowed with an increase in the ectopically erupted permanent teeth. 8. In patients in whom the permanent dentition was formed without occlusal guidance, the basal arch length and dental arch length were large and basal arch width and dental arch width were small. 9. In cases which were followed from the deciduous dentitions to permanent dentitions, the anterior tooth area at the stage of the mixed dentition was frequently crowded. Occlusal guidance was carried out in more than half of these cases.

Humans↗
PubMedDate not supplied

[Relationship between the width of maxillary central incisors and philtrum].

Size of central incisors is a significant factor in selection of anterior teeth for all types of dentures. The purpose of this study was to evaluate the relationship between the width of maxillary central incisors and philtrum. The average width of the central incisors and philtrum observed in male subjects were 8.510 mm. (right), 8.516 mm. (left) and 14.105 mm. Those in female subjects were 8.280 mm. (right), 8.293 mm. (left) and 12.271 mm. There was a significant difference (p less than 0.05) in size between the width of each central incisor and philtrum for either male or female subjects. However, there was a direct correlation between the width of the central incisors and philtrum in these 200 subjects (p less than 0.05).

Female↗
PubMed1987

Heterochrony in the development of vestigial and functional deciduous incisors in rabbits (Oryctolagus cuniculus L.).

Foetal and postnatal development of vestigial and functional deciduous incisors was reexamined using routine serial histological sections of maxillae and mandibles at daily intervals from day 16 postconception to postnatal day 15. It was found that the development of the maxillary and mandibular vestigial incisor teeth was more rapid than that of the functional incisors and that, of the functional incisors, the maxillary posterior deciduous incisors were the slowest to develop. It appeared from this study that a basic morphogenetic requirement for unfolding structure, ie, developmental timing, was not critical in generating hypsodont or brachydont teeth. A proposition has been made that originally juvenile stages of odontogenesis represent a continuously growing system, which during evolution has successively become typical for adult descendants.

Animals↗
PubMed1983

Eruption of incisor teeth in cleft lip and palate.

Longitudinal frontal and lateral cephalometric radiographs were used to study the path of eruption of the permanent central incisors approximating the cleft areas in 15 subjects with unilateral and 7 subjects with bilateral complete clefts of the lip and palate, aged between 3 years 8 months and 9 years. Tracings from the longitudinal transparent templates of the Bolton Standards subjects were used as controls for comparative purposes. The findings indicate that the pattern of eruption of the maxillary central incisor follows the pattern of alveolar development in the cleft subjects. The position of the premaxilla subsequent to cleft repair influences the eruption pattern of the maxillary central incisors approximating the cleft areas. The central incisors erupt down and back, and become more retroclined and retropositioned within the nasomaxillary complex, with increment in age. The crowns of the central incisors approximating the cleft in unilateral cleft lip and palate subjects progressively tipped more towards the cleft with age.

Cephalometry↗
PubMed1982

Clinical crown length of incisors in 13-year-old boys and girls with different malocclusions.

The clinical crown length of incisors in 13-year-old children with different malocclusions was compared. The children were classified as follows: II1 Class II, division 1 cases with deep overbite. II2 Class II, division 2 cases. III Class III cases with complete or partial frontal inversion. IV Cases with aplasia of the upper laterals. The groups were subdivided by sex and recruitment was continued until each group contained 30 boys and 30 girls. The results are shown in Table 2. Good agreement was found between boys and girls with respect to the results of measurement of the different variables, comparison of the different malocclusion groups showed that the clinical crown length was greater in groups II1 and III than in groups II2 and IV. Comparison of groups II1 and III showed a somewhat greater crown length of the lower incisors in the prenormal children. The findings are discussed in relation to the following three hypotheses: 1. Proclined incisors have a longer clinical crown than upright incisors. 2. The incisors overerupt in children with large lower facial height, leading to an increased clinical crown length. 3. Local gingival conditions influence the clinical crown length.

Adolescent↗
PubMed1995

Multidisciplinary restoration of fused maxillary incisors: a case report.

This case report describes the endodontic, periodontal, and restorative treatment of a maxillary incisor with unusual external and internal anatomy. The right central and lateral incisors had fused, resulting in an oversized unaesthetic central incisor. A small diastema was present between the fused central incisor and the canine. Since overpreparation of the tooth during restoration was anticipated, endodontic therapy was accomplished. Periodontal flap surgery provided an opportunity to reduce the root diameter and narrow the emergence profile of the tooth and to eliminate a plaque-retentive palatogingival groove. A cast post and core rigidly obturated the canal space and provided a preparation on which to fabricate a metal-ceramic restoration simulating the replacement of the right lateral incisor. The final restoration provided significant aesthetic improvement. The learning objective of this article is to familiarize the reader with multidisciplinary restorations.

Adult↗
PubMed1995

Crown dilaceration of permanent incisors following trauma to their primary predecessors.

Crown dilaceration of a permanent tooth constitutes 3% of traumatic injuries to developing teeth. It usually involves the maxillary incisors and less frequently their mandibular counterparts. This report concerns a patient, whose primary mandibular central incisors, following a fall at the age of 14 months, sustained partial avulsion with displacement. The teeth were repositioned by the father, with the aid of a pediatrician, and without the assistance of a dentist. The patient presented at the age of 8 years, and, following clinical and radiographic examination, a diagnosis was made of crown dilaceration with lingual displacement of the incisal third of the permanent mandibular central incisors, and hypoplastic enamel on all but the gingival third of their crowns. In addition to this, a supernumerary tooth was discovered labial to and between the mandibular right permanent central incisor and the mandibular right primary lateral incisor. After a brief review of the literature, the treatment of this patient is described and the restoration of the dilacerated teeth, followed by a discussion on crown dilaceration and issues concerning the restoration of such teeth.

Child↗
PubMed1996

An alternative approach to replacement of a congenitally missing maxillary central incisor: a case report.

The prosthetic replacement of a missing central incisor is described. The left anterior teeth were transformed, through the placement of laminate veneers, to simulate a complete dentition; the lateral incisor was made to look like a central incisor, the canine like a lateral incisor, and the first premolar like a canine. The right central and lateral incisors were also restored for esthetic purposes. The most important factors associated with this type of case are discussed in detail.

Aluminum Silicates↗
PubMed1998

Effect of presurgical incisor extrusion on stability of anterior open bite malocclusion treated with orthognathic surgery.

The records of 40 nongrowing open bite patients treated with orthodontics and maxillary surgery were divided into two groups and evaluated. The extrusion group (n = 19) included those patients who had presurgical maxillary incisor extrusion of at least 1.5 mm. In the nonextrusion group (n = 21), the maxillary incisors were maintained or intruded prior to surgery. Statistical analysis showed no relationship between presurgical extrusion of the maxillary incisors and the stability of open bite correction; the maxillary incisors were generally stable long term in both groups. Overbite decreased a mean of -0.97 mm in the extrusion group and -0.67 mm in the nonextrusion group during the mean 5-year 10-month follow-up period after appliance removal. Twenty-five percent (10 of 40, 5 from each group) of the sample had no incisal overlap long term. These findings suggest that a moderate amount of presurgical incisor extrusion or lack of extrusion are stable long term and have little influence on posttreatment stability of open bites. The decrease in overbite observed after treatment may result from the influence of various dental, skeletal, and soft tissue factors rather than from any single factor.

Adult↗
PubMed1991

A pilot study of the effects of mechanical shortening of ewes' incisors (bite correction) on body weight and the development of periodontal disease.

A field trial was set up to determine the effects of mechanical shortening of long incisors (bite correction) of ewes with early periodontal disease on the progress of the disease and on their body weights. On a farm near Te Anau with a high prevalence of periodontal disease in sheep, the body weights of 75 sound mouth ewes and two groups each of 75 ewes with periodontal disease were recorded. At the start of the trial, the incisors of the ewes in one of the groups with periodontal disease were shortened using a grinder. The trial ran for 2 years. The mouths of almost all the sheep which had sound mouths at the start of the trial remained sound throughout. This suggests that on periodontal disease-prone farms it may be possible to select ewes at 3 or 4 years of age which will retain sound mouths throughout much of thei-r productive lives. Throughout the trial, sheep with advanced periodontal disease tended to be lighter than sheep with mild periodontal disease and those in turn tended to be lighter than sheep with sound mouths. Mechanical shortening of the incisors did not alter the proportion which subsequently developed advanced periodontal disease. Seventeen to eighteen percent of ewes in both periodontal disease groups had developed advanced periodontal disease by the end of the trial. There was no significant difference in body weight between the group with shortened incisors and the group with untreated periodontal disease. Consequently, the trial provides no evidence that the mechanical shortening of the incisors of ewes will improve their productivity.

Journal Article↗
PubMed1993

Comparison of rates of enamel synthesis in impeded and unimpeded rat incisors.

Periodic intubations of rats with solutions of fluoride (F) lead to the appearance of bands of disrupted pigmentation in continuously erupting incisors. Distances between fluorotic bands reflect time intervals between intubations. In this experiment, the periodicity of fluorotic banding was used for estimation of the rate of enamel synthesis in impeded and unimpeded rat incisors. Rats kept on a low-F diet and distilled water were intubated two or four times per week with 2 mg NaF/150 g body weight. In a group of rats, one of the mandibular incisors was cut at the gingival margin after two weeks, and intubations were continued for an additional two weeks. In another group of F-intubated rats, incisors were cut or notched at the gingival margin twice, six days apart. Control rats either received the same periodic F intubations or were maintained on the low-F diet without intubation. Measurements of spacing between fluorotic bands were identical in impeded and unimpeded teeth, even though the latter erupted at a faster rate. In an unimpeded mandibular incisors, there was a significant elongation of the secretory zone and a shortening of the pigmentation zone, resulting in reduced pigmentation intensity of the erupted portions of the teeth. The results show that the rate of enamel synthesis is independent of the eruption rate.

Amelogenesis↗
PubMed1976

Movement of entire cell populations during renewal of the rat incisor as shown by radoioautography after labeling with 3H-thymidine. The concept of a continuously differentiating cross-sectional segment. (With an appendix on the development of the periodontal ligament).

Renewal of the rat incisor was studied in three dimensions by employing a serial cross-sectioning technique to locate the boundary between labeled and unlabeled cells in the enamel organ and odontoblast layer at various times after a single injection of 3H-thymidine. This boundary, or leading edge of the front of labeling, was graphically illustrated through point-plotting reconstruction of the labial surface of the incisor. At one hour after the injection of 3H-thymidine the front of labeled ameloblasts was located within the presecretory zone related to early predentin secretion. This front formed a "C"-shaped curve stretching across the labial surface of the tooth from the lateral to the mesial cemento-enamel junction. The "C" was open anteriorly and the lateral arm extended almost twice as far incisally as the mesial arm. The edge of the front of labeled odontoblasts was positioned apical to and parallel with this "C"-shaped curve. The morphological appearance of all cells along each respective front was found to be similar. As the fronts of labeled ameloblasts and labeled odontoblasts moved forward with the erupting incisor, the cells along these fronts differentiated simultaneously and subsequently formed enamel and dentin. Throughout this movement the distance between fixed points along the leading edge of the front of labeled ameloblasts, and its positional relationship to the front of labeled odontoblasts, did not change appreciably. This indicated that cells of the tooth were being carried incisally at a uniform speed. It was concluded that renewal in the rat incisor consists of the generation by the bulbous part of the odontogenic organ of epithelial "U"-shaped cross-sectional segments which enclose a core of pulp. As this segment is transported towards the gingival margin, cellular differentiation and subsequent formation of hard tissue is seen to begin at the central labial side of the segment and to progress in a mesial and lateral direction towards the lingual side. In the process, the limits of the enamel organ at the mesial and lateral cemento-enamel junctions are established and the entire circumference of the segment is eventually enclosed by a rim of dentin.

Ameloblasts↗
PubMed1980

Sex differences in lingual marginal ridging on the human maxillary central incisor.

Although incisor dimensions are on average larger in males, at least one incisor trait, lingual marginal ridging, is significantly more common in females. This is documented for the upper central incisor in a collation of 38 samples of living populations representing six racial groups. Caucasian, Asian, Polynesian, Melanesian, and American Indian females each possess significantly higher frequencies than their male counterparts. American Blacks do not show a sex difference. Sex differences in the duration and rate of incisor crown development do not explain this dimorphism. Possible underlying genetic causes are reviewed, and the hypothesis is proposed that relevant portions of both X chromosomes in females are contributing to greater trait expression.

Asian People↗