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At least 163 records · Page 9Linked to original sources
PubMed1989

Enamel hypoplasia of a maxillary central incisor.

This article describes a case of a permanent central incisor with enamel hypoplasia. A 7-year-old patient had suffered an injury in a car accident when she was 2 1/2 years old. The maxillary right central deciduous incisor was lost in the accident. At the time of examination a fistula was present buccally to the maxillary right permanent incisor, which had erupted only 3 mm into the mouth. The maxillary left central incisor had erupted fully. After clinical and radiographic examination the lost deciduous incisor was found in the bone buccally to the permanent incisor. The deciduous tooth was extracted surgically, the fistula healed and the gingiva became normal. The permanent incisor had a 3-mm-wide zone of hypoplastic enamel on the buccal surface of the crown.

Child↗
PubMed2005

Managing congenitally missing lateral incisors. Part I: Canine substitution.

UNLABELLED: Dentists often encounter patients with missing or malformed teeth. The maxillary lateral incisor is the second most common congenitally absent tooth. There are three treatment options that exist for replacing missing lateral incisors. They include canine substitution, a tooth-supported restoration, or a single-tooth implant. Selecting the appropriate option depends on the malocclusion, specific space requirements, tooth-size relationship, and size and shape of the canine. The ideal treatment is the most conservative option that satisfies individual esthetic and functional requirements. Often the ideal option is canine substitution. Although the orthodontist positions the canine in the most esthetic and functional location, the restorative dentist often needs to place a porcelain veneer or crown to re-create normal lateral incisor shape and color. This article closely examines patient selection and illustrates the importance of interdisciplinary treatment planning to achieve optimal esthetics. It is the first in a three-part series discussing the three treatment alternatives for replacing missing lateral incisors. CLINICAL SIGNIFICANCE: Patients with congenitally missing lateral incisors often raise difficult treatment planning issues. Therefore, to produce the most predictable esthetic results, it is important to choose the treatment that will best address the initial diagnosis. This article is the first in a three-part series that describes the different treatments available for patients with congenitally missing lateral incisors. This first article focuses on canine substitution as a method of tooth replacement for these missing teeth. The general dentist will learn to evaluate specific patient selection criteria and determine whether canine substitution is an appropriate treatment alternative for replacing missing lateral incisors. The orthodontist will understand how to position the canines to satisfy functional requirements and achieve proper esthetics. Finally, the importance of interdisciplinary team treatment planning is emphasized as a requirement for achieving optimal final esthetics.

Adolescent↗
PubMed1999

Equine dental disease part 1: a long-term study of 400 cases: disorders of incisor, canine and first premolar teeth.

A review of 400 horses referred because of dental disorders showed 44 cases to suffer from primary disorders of their incisors and 11 from canine or 1st premolar teeth disorders. The remaining 345 horses suffered from primary disorders of the cheek teeth. Disorders of incisors included traumatic damage to teeth and their supporting bones, retained deciduous, displaced and supernumerary incisors; brachygnathia and abnormalities of wear, with most of the latter disorders being secondary to primary disorders of the cheek teeth Only 3 cases of apical infection of incisors were recognised. Most cases of fractured incisors responded well to conservative therapy. Retained deciduous incisors were extracted, but most cases with supernumerary and displaced incisors, or brachygnathia were treated conservatively. Most disorders of the canine and 1st premolar were developmental displacements that caused bitting problems (abnormalities of head movement associated with the bit), and these cases responded well to extraction of the displaced teeth.

Animals↗
PubMed2004

Modulation of clinical expression of plaque-induced gingivitis: effect of incisor crown form.

Evidence indicates that incisor crown form correlates with clinical periodontal features. It was hypothesized that incisor crown form may explain subject differences in gingivitis expression. The present experimental gingivitis study aimed to assess the effect of incisor crown form on plaque accumulation and gingival inflammation, and on individual susceptibility to plaque-induced gingivitis. Eighty-five periodontally healthy subjects were evaluated. A negative correlation was found between incisor crown width/crown length ratio and bleeding score (p = 0.045). From the 85 subjects, two groups of subjects with either 'long-narrow' or 'short-wide' incisor form were identified. The 'long-narrow' group had a significantly higher bleeding score than the 'short-wide' group (p = 0.014). No significant differences were found in the incisor crown width/crown length ratio between previously identified 'high responder' and 'low responder' subjects (Trombelli et al., 2004a). In conclusion, incisor crown form appears to affect the bleeding response of inflamed gingival tissues, while it exerts no influence on explaining differences in individuals' susceptibility to plaque-induced gingivitis.

Adult↗
PubMed2000

The origin and development of the upper lateral incisor and premaxilla in normal and cleft lip/palate monkeys induced with cyclophosphamide.

OBJECTIVE: Cleft lip/palate (CLP) is a common human congenital defect in which the maxillary lateral incisors are often absent, malformed, and malpositioned. The present study was designed to examine the origin of the upper primary lateral incisor relative to the medial nasal process (MNP) and maxillary process (MP) fusion area and to the premaxillary/maxillary (incisive) suture in monkeys. METHOD: Scanning electron microscopy, histology, skeletal staining, and drying techniques were used to study facial development in embryo and fetal monkey specimens. A teratogenic dose of cyclophosphamide was administered to pregnant monkeys prior to fusion of the MNP and MP and fetuses were examined for CLP. RESULTS: Formation of the anterior maxilla involved fusion of the MNP and MP at stages 14-18. At stages 18-20, the palatal portion of the MNP had formed the medial and lateral incisive mounds. By stage 22, the upper primary lateral incisor has formed within the MP, lateral to the MNP/MP fusion area and to the ossifying premaxilla. Ossification of the premaxilla begins in the MNP and subsequently spreads laterally across the MNP/MP fusion area into the MP. Accordingly, the lateral incisor undergoes a complex positional shift (mainly medial) relative to the incisive suture both prenatally and postnatally and is finally located medial to the suture. Examination of the cyclophosphamide-induced CLP fetuses showed that the lateral incisor is located lateral to the alveolar cleft and does not shift medial to the incisive suture. CONCLUSION: Understanding the origin of the lateral incisor (the tooth closest to the cleft) and the shift after its formation provides clues to high incidence of malformations and ectopia of this incisor in cleft patients.

Alveolar Process↗
PubMed2003

Dental anomalies of the permanent lateral incisors and prevalence of hypodontia outside the cleft area in complete unilateral cleft lip and palate.

OBJECTIVE: To determine in complete unilateral cleft lip and palate (UCLP) subjects the characteristics (location, shape) of the cleft-side lateral incisor. The presence of a supernumerary tooth at the cleft side and the prevalence of hypodontia outside the cleft area were evaluated. A comparison was made of the shape of the cleft side lateral incisor to its contralateral incisor. SETTING: Hospital for Rehabilitation of Craniofacial Anomalies (HRCA), Sao Paulo, Brazil. PATIENTS: Orthopantomograms of 203 subjects with UCLP and without syndromes were chronologically selected from the HRCA data bank, within an age range of 5 to 10 years. OUTCOME MEASURE: Orthopantomograms were analyzed by the same observer according to established criteria. RESULTS: There were no statistically significant differences between sexes for any of the criteria studied. The cleft-side lateral incisor was present in 50.2%, and it was more commonly located at the distal side (76.5%). The congenital absence of the cleft-side lateral incisor was observed in 49.8% of the sample, and its antimere was congenitally missing in 10.9%, this difference being statistically significant. The most commonly missing tooth outside the cleft area was the maxillary second premolar. CONCLUSIONS: The high prevalence of hypodontia of the permanent lateral incisor in the cleft side showed that the cleft could play an important role in this absence. There were different patterns for the presence of the cleft-side lateral incisor.

Anodontia↗
PubMed2000

Labiolingual and mesiodistal positioning of maxillary permanent incisors during the eruption process.

This study aimed to establish radiographical parameters concerning the tipping, the labiolingual positioning and the angulation of the maxillary permanent incisors in the mixed dentition. Three groups of 20 cephalograms and 20 orthopantomographic radiographs taken from children aging from 7 to 12 years old, with normal occlusion were compared. The Group I presented only the eruption of the central permanent incisors, the Group II presented both the central and lateral permanent incisors and the Group III presented central, lateral incisors and permanent canine teeth. The tipping and the labiolingual positioning were measured, respectively, using U1/PP and U1<-->AVERT. Mesiodistally, the angles between the teeth axis and the line that touched the lower border of the orbit in the orthopantomographic radiographs were measured. The mean values of tipping, labiolingual positioning and angulation of the central and lateral incisors obtained from Groups I, II and III were respectively 112 degrees, 1.2 mm, 90.4 degrees and 91.7 degrees; 112 degrees, 2.6 mm, 89.5 degrees and 96.8 degrees and 114 degrees, 2.7 mm, 87.4 degrees and 92.6 degrees. The tipping levels were similar for all groups, the mean values of the labiolingual positioning were significantly different at 5% when Group I was compared to both Groups II and III. And the mean values of the angulation were significantly different 5% for the central incisors between Groups I and III, and at 1% for the lateral incisors between Groups I and II, and, II and III.

Analysis of Variance↗
PubMed1999

Alterations in the incisor development in the Tabby mouse.

The X-linked tabby (Ta) syndrome in the mouse is homologous to the hypohidrotic ectodermal dysplasia (HED) in humans. As in humans with HED, Ta mice exhibit hypohidrosis, characteristic defects of hairs and tooth abnormalities. To analyze the effects of Ta mutation on lower incisor development, histology, morphometry and computer-aided 3D reconstructions were combined. We observed that Ta mutation had major consequences for incisor development leading to abnormal tooth size and shape, change in the balance between prospective crown- and root-analog tissues and retarded cytodifferentiations. The decrease in size of Ta incisor was observed at ED13.5 and mainly involved the width of the tooth bud. At ED14.5-15.5, the incisor appeared shorter and narrower in the Ta than in the wild type (WT). Growth alterations affected the diameter to a greater extent than the length of the Ta incisor. From ED14.5, changes in the shape interfered with the medio-lateral asymmetry and alterations in the posterior growth of the cervical loop led to a loss of the labio-lingual asymmetry until ED17.0. Although the enamel organ in Ta incisors was smaller than in the WT, a larger proportion of the dental papilla was covered by preameloblasts-ameloblasts. These changes apparently resulted from reduced development of the lingual part of the enamel organ and might be correlated with a possible heterogeneity in the development of the enamel organ, as demonstrated for upper incisors. Our observations suggest independent development of the labial and lingual parts of the cervical loop. Furthermore, it appeared that the consequences of Ta mutation could not be interpreted only as a delay in tooth development.

Animals↗
PubMed1999

Morphogenesis of the lower incisor in the mouse from the bud to early bell stage.

The development of the lower incisor in the mouse was investigated from histological sections using computer-aided 3D reconstructions. At ED 13.0, the incisor was still at the bud stage. At ED 13.5, the initial cap was delimited by a short cervical loop, the development of which proceeded on the labial side, but was largely retarded on the medial side. This difference was maintained up to ED 15.0. From ED 16.0, the bell stage was achieved. Metaphases had a ubiquitous distribution both in the enamel organ and in the dental papilla from the bud to early bell stage. Apoptosis gradually increased in the mesenchyme posteriorly to the labial cervical loop from ED 13.5 to 14.0 and then disappeared; this apoptosis was not related to the posterior growth of the incisor. From ED 13.5, a high apoptotic activity was observed in the stalk. A focal area of apoptosis was observed at ED 13.5 in the enamel organ, approaching the epithelio-mesenchymal junction at the future tip of the incisor. There, the inner dental epithelium formed a bulbous protrusion towards dental papilla, reminiscent of the secondary enamel knot of mouse molars. This epithelial protrusion was still maintained at the bell stage. The enamel knot in the incisor demonstrated specific features, different from those characterizing the enamel knot in the molar: the concentric arrangement of epithelial cells was much less prominent and the occurrence of apoptosis was very transitory in the incisor at ED 13.5. The disappearance of the enamel knot despite a low apoptotic activity and the maintenance of the protrusion suggested a histological reorganization specific for rodent incisor.

Animals↗
PubMed2005

An anterior tooth size comparison in unilateral and bilateral congenitally absent maxillary lateral incisors.

The purpose of this study is to compare the anterior tooth size width in patients with congenitally missing maxillary lateral incisors using the Bolton Index and divine proportion. The study sample consisted of thirty pairs of orthodontic models with unilateral (twelve patients; 7 females, 5 males) and bilateral (eighteen patients; 13 females, 5 males) absence of maxillary lateral incisors. The mean ages of the selected cases were 17.7 and 17.5 years, respectively. Descriptive statistics were used for the data analysis. The result showed the mean of the Bolton Index in cases with bilateral absence was closer to the Bolton mean than in cases with unilateral absence. In the unilateral absence cases the width of the existing lateral incisor (5.5 mm) was an average of 1.00 mm less compared to the standard mean (6.5 mm). The divine proportion showed the maxillary central incisors were small in width as indicated by the adjusted value or they were slightly larger in width than the mandibular central incisors. In cases with unilateral and bilateral absence the Bolton Index exhibited maxillary insufficiency, which was confirmed by evaluating the divine proportion of the maxillary and mandibular incisors. The result of the present study will be of great help to both the orthodontist, whether to open or close the space, and to the prosthodontist to restore the missing teeth of patients having missing maxillary lateral incisors.

Adolescent↗
PubMed2005

Labial-cervical-vertical groove in maxillary permanent incisors--prevalence, severity, and affected soft tissue.

OBJECTIVES: To investigate the prevalence and severity of a labial-cervical-vertical groove (LCVG) in maxillary permanent incisors and its effect on the associated gingival tissue. METHODS: A total of 600 adolescents (293 boys and 307 girls, mean age 13.6+/-1.99 years) were randomly selected and examined for the presence of LCVG. The deformity was classified as mild, moderate, or severe according to predetermined criteria. Gingival coverage at the groove site was defined as normal, partial, and irregular. RESULTS: LCVG was found in 27 adolescents (4.5%). It was unilateral in 24 (89%) and bilateral in 3 (11%). The ratio of central to lateral incisors was 29:1. No sexual dimorphism or side prevalence were found. Mild LCVG was found in 22 incisors, moderate LCVG in 7 incisors, and severe LCVG in one incisor. Moderate LCVG was 5 to 6 times more susceptible to partial or irregular coverage of the gingival margin than mild LCVG. The gingival sulcus in teeth with LCVG demonstrated a significant (P = .001) increase in depth compared to non-LCVG teeth (1.55+/-0.90 mm vs 1.18+/-0.75 mm). CONCLUSIONS: An LCVG is a deformity confined predominantly to a single permanent maxillary central incisor. Its prevalence is not connected with gender. Most LCVGs are mild and often difficult to detect. However, the greater the severity, the more gingival irregularity is associated. This and the increase in sulcus depth in LCVG incisors are adverse predispositions for periodontal sequelae, calling for cautious oral hygiene maintenance.

Adolescent↗
PubMed2005

Retrospective analysis of factors influencing the eruption of delayed permanent incisors after supernumerary tooth removal.

AIM: This was to assess the predictability of eruption of delayed permanent incisors after supernumerary removal and creation of adequate space, in relation to: root maturity, degree of vertical impaction, and degree of angulation of impaction. METHODS: The dental records of children with supernumerary teeth delaying the eruption of permanent incisors were analysed. The type of a supernumerary tooth, its location and position were recorded, along with the stage of root maturation, angulation and vertical distance of impaction of the permanent incisor. At the initial surgery, the unerupted supernumerary tooth and any retained primary incisors were removed. The unerupted permanent incisor was not exposed. If necessary, the maxillary primary canines were removed to create sufficient space for eruption of the delayed permanent tooth. A secondary surgical procedure was planned after 18 months if there was no significant progress of the permanent tooth towards eruption. STATISTICS: All data were entered onto a Microsoft Excel spread sheet and analysed using Fisher's Exact Tests throughout due to the small numbers. RESULTS: Sixty-six supernumerary teeth were removed, 22 from boys and 44 from girls with ages ranging from 6 to 10 years 6 months at the time of surgery. Primary canines were extracted in 59.1% of cases. Spontaneous eruption occurred in 89.4% of delayed permanent teeth. The mean time to eruption was 9.2 months (median = 7 months). There was no statistically significant association between tooth eruption and root maturity or the degree of vertical impaction. There was an association between eruption and the degree of the angle of impaction of the permanent incisor (p<0.05). CONCLUSION: The majority of delayed permanent teeth erupt spontaneously if sufficient space is available or created at the time of removal of the unerupted supernumerary. The angulation of impaction of the permanent incisor is associated with a delay in eruption.

Child↗
PubMed1990

[A study of dynamics of orthodontic archwire on the dental arch. 1. Distribution of orthodontic forces during labial movement of bilateral incisors].

The study on labial movement of maxillary unilateral incisor had been reported previously. This study was the case of maxillary bilateral incisors. Orthodontic forces during labial movement of maxillary bilateral incisors which were produced by stainless steel archwire with vertical loops and nickel titanium archwire, were measured and were examined the distribution of orthodontic forces to the dental arch in the experimental apparatus with strain gauges. The following results were found: 1. In nickel titanium archwire, orthodontic forces were distributed to the entire dental arch, and the distribution of orthodontic forces could be classified into three types, which were similar to the previous study. 2. In stainless steel archwire with vertical loops, orthodontic forces were distributed only to bilateral incisors and adjacent tooth to bilateral incisors. 3. When bilateral incisors displaced lingually, it showed that there were additional orthodontic forces distributions as if two unilateral distributions were overlapped. 4. For maxillary bilateral incisors were moved in optimum force, some consideration to adjust the loops of stainless steel archwire was needed.

Dental Stress Analysis↗
PubMed1989

[Comparisons of bioavailability of various calcium salts. Utilization incisor dentin in parathyroidectomized rats].

In the present study, we compared the bioavailability of various calcium salts in the diet such as calcium lactate, calcium carbonate and calcium phosphate by examining the effects of these calcium salts on serum calcium concentration and on the mineralization of incisor dentin in parathyroidectomized (PTXed) rats. Each rat was given daily 12 g of a low calcium (0.1% Ca) diet beginning from 3 days before the operation and continuing for 11 days after. Then the diet was changed to those containing various calcium salts (1.5% Ca). The serum calcium and phosphorous concentrations were examined every three days, just before feeding time and 6 hours after. The degree and site of the mineralization of incisor dentin were examined histologically by a time marking method using lead acetate. In the PTXed rats maintained on a low calcium diet, the serum calcium concentration decreased to about 4.5 mg/dl and the mineralization of incisor dentin was inhibited. On the 11th day, just before feeding on diets containing various calcium salts, the serum calcium concentrations were very similar for each group, but at 6 hours after feeding, concentration was 7.6 mg/dl in the calcium lactate group, 6.2 mg/dl in the calcium carbonate group and 4.8 mg/dl in the calcium phosphate group. On the 17th day following administration of the high calcium diets, the serum calcium concentrations were 9.8 mg/dl in the calcium lactate group, 8.4 mg/dl in the calcium carbonate group and 4.4 mg/dl in the calcium phosphate group. Mineralization of the incisor dentin was best in the calcium lactate group, moderate in the calcium carbonate group and poor in the calcium phosphate group. We also examined the effects of dietary phosphorus contents on serum calcium concentrations and on the mineralization of incisor dentin using PTXed rats. On the 17th day following the administration of diets (1.5% Ca, with calcium lactate) containing various amounts of phosphorus, the serum calcium concentrations in the calcium lactate group were 8.8 mg/dl (0.4% P), 6.9 mg/dl (0.8% P) and 4.2 mg/dl (1.6% P) respectively. Mineralization of incisor dentin was also inhibited in rats fed a high phosphorus diet. These results suggest that in PTXed rats, absorption of calcium from the intestines and mineralization of the incisor dentin is best by the administration of calcium lactate, moderate by calcium carbonate and poor by calcium phosphate, and that phosphorus in the diet inhibits calcium absorption from the intestines.

Animals↗
PubMed1989

[A case of horizontal impaction of mandibular left and right deciduous central incisors].

This paper reports on a rare case of horizontal impaction of the mandibular left and right deciduous central incisors. The patient was a 4 year and 7-month-old-girl at the time of first visit to our clinic. She had no previous history, and there was no family history or anomaly in her general physical condition. All the deciduous teeth except the mandibular left and right deciduous central incisors had already erupted. The right deciduous central incisor was impacted completely and the left one erupted with its incisal edge about 2 mm at the lingual gingiva. In the X-ray examination, the horizontal impaction of the mandibular left and right deciduous incisors were noted. There were no cysts, odontoma or tumors. Both of them were extracted to prevent loss of space for the permanent central incisors. Each root of both teeth was curved 90 degrees in the lingual direction at half of length of the root. There was no anomaly of figure and color in their crowns. In the histopathologic examination, there was no anomaly except for the small root resorption at the labial and lingual sides. 3 years and 3 months after extraction of the deciduous central incisors, approximately two thirds of the crowns of the left and right mandibular permanent central incisors have erupted. Both of them incline to the lingual direction and rotate and there is a space of about 5 mm between them. This case is still under observation.

Child, Preschool↗
PubMed1989

[Access cavity preparation for mandibular incisors with suspected two canals].

One of the common reasons for endodontic failure is incomplete root canal obturation. According to previous studies, about 10-45% of all lower incisors have two canals. The purposes of this study were: 1. determine the incidence of double canals in the lower incisors among Chinese; 2. evaluate the usefulness of X rays for locating double canals in the lower incisors; and 3. propose a method of access cavity preparation for lower incisors when double canals are diagnosed. One hundred lower incisors were collected and checked by dental X ray, mesiodistally, buccolingually and at a 30 degrees mesial shift, in order to determine the incidence of double canals and evaluate their images on film. In addition, a method for drawing the pathway of the double canals from the apex to the incisal edge, as a reference for access cavity preparation, was proposed. The results of this study showed that 36 out of the 100 lower incisors had double canals and only two of them had two separate apical foramina. Clinically, when the X ray image of the lower incisor canal is obscure or missing at the middle third of the root, it is best to extend the access cavity to the incisal edge in order to find the lingual canal.

Dental Cavity Preparation↗
PubMed1989

[Long-term observation of two post-treatment cases with an impacted maxillary central incisor corrected by orthodontic treatment].

UNLABELLED: This article describes long-term observation of two post treatment cases with an impacted maxillary central incisor corrected by orthodontic treatment. [Case 1] Age at first examination: 11 years and 1 month. Chief complaint: Retarded eruption of a maxillary right incisor and crowding of teeth. DIAGNOSIS: No skeletal problems were identified. Crown axis inclination of the impacted tooth showed 104.0 degrees. Root axis inclination showed 87.0 degrees. Treatment plan: [formula; see text] extraction, traction of the maxillary right incisor, edgewise method. Treatment time: 4 years and 3 months. [Case 2] Age at first examination: 8 years and 8 months. Chief complaint: Retarded eruption of a maxillary left incisor. DIAGNOSIS: No skeletal problems were identified. Crown axis inclination of the impacted tooth showed 112.0 degrees. Root axis inclination showed 88.0 degrees. Treatment plan: Traction of maxillary left incisor, edgewise method. Treatment time: 5 years and 6 months. The findings were as follows; 1) When the active treatment was finished, no pulp necrosis nor any resorption of root or alveolar bone was found in the two cases. 2) At present, the crown axis inclination is restored to normal in both cases. 3) The impacted maxillary central incisors were treated to the normal position in the dental archs, and the condition and the tissues around are good. The foregoing results, we are sure, can be an important traction of the impacted maxillary central incisor.

Cephalometry↗
PubMed1994

Traumatic injuries to permanent incisors: a case report.

A case report involving traumatized maxillary incisors is presented. The right central and lateral incisors were avulsed by direct trauma and were not found. The left central incisor was luxated and the left lateral incisor was fractured at the coronal portion. Placement of implant fixtures was selected as treatment to prevent resorption of alveolar bone and to maintain the integrity of intact adjacent teeth. The right incisors were replaced with two osseointegrated implants. The left central incisor was endodontically treated and a cast post and core was bonded into the root canal. All three of these teeth were restored with porcelain-fused-to-metal crowns. A composite resin restoration was placed on the left lateral incisor. The esthetic and functional results were satisfactory.

Accidents, Traffic↗