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A case is described in which bilateral supplemental maxillary central incisors were found in a 9-year-old boy. The occurrence has been reported previously of bilateral supplemental maxillary lateral incisors but not of central incisors.
A study of 1016 12-year-old Nigerian children was carried out to assess the relationship between traumatic injuries of anterior teeth, incisor overjet and lip competence. The prevalence of dental injuries was 10.9% which confirmed the results of previous studies. More boys than girls sustained injuries to their teeth. There were, however, no significant sex differences in increased overjet or lip competence. Of the 111 children with traumatic dental injuries, 71 (64.0%) had increased incisor overjet (> 3 mm) compared to 257 of the 905 children (28.4%) in the non-trauma group. Similarly, 72 (64.9%) of the trauma group had inadequate lip coverage compared to 224 (24.8%) in the non-trauma group. These differences were statistically significant (P < 0.001). It is concluded that incisor overjet of more than 3 mm and incompetent lips are significant predisposing factors to anterior dental injury in Nigerian children.
This paper describes talon cusp in an ancient skeleton and is a rare report of its occurrence in a primary lateral incisor. As well as talon cusp, the affected incisor also shows abnormal widening, probably representing a double tooth. There is also a supernumerary permanent incisor. The report shows that talon cusp existed in British populations more than 600 years before the first written description. A brief review of the literature on the occurrence of talon cusp in the primary dentition is presented.
OBJECTIVE: To assess the outcome of treatment of hypomineralized molars and incisors of unknown aetiology (MIH) in 18-year-olds. DESIGN: A follow-up study including clinical examination, panoramic radiography and intraoral photos. SAMPLE AND METHOD: Seventy-six individuals treated at the Eastman Dental Institute in Stockholm during 1978-2001 with the diagnosis MIH. Severity of enamel defects in molars and incisors, prevalence and distribution of extracted molars, type, quality and median duration of restorations, periradicular condition of affected molars, dental occlusion and space closure in cases of extraction, as well as the individual's satisfaction with the treatment, were assessed. RESULTS: Severe defects with enamel surface breakdown in all four molars occurred in 42% of the individuals and 29% had at least one incisor with yellow/brown opacity in the enamel. At follow up, 42% of the individuals had at least one molar extracted; 18% had all four molars extracted. The median duration of the molar restorations (n = 153) was 5 years. Of the individuals with restored molars, 48% had at least one unacceptable restoration. Periradicular pathology was observed in three molars. The sagittal relations did not differ between individuals with and without extraction of molars. Space closure was acceptable in 87% of the individuals with extracted molars. Eighty percent were satisfied with the treatment. CONCLUSIONS: Extraction of molars with severe enamel defects gave good or acceptable results in a majority of the patients while conservative restorative treatment resulted in a need for additional treatment in approximately half of the patients.
Humans with normal occlusion usually perform gum-chewing movements in a characteristic manner. The purpose of present study was to examine whether the variability of masticatory jaw movement in children with incisor crossbite is greater than that in children with normal occlusions, and if so, to examine whether correction of the crossbite results in a significant reduction in the variability. The variance in masticatory jaw movement trajectory was investigated in 10 children with acceptable occlusion and 11 children with crossbite of one or two incisors. The lower incisor-point movements during chewing of standardized gum were monitored using a 3D tracking device. The deviation of the jaw-closing trajectory from a best-fit plane was then evaluated for each chewing cycle. Subsequently, variance in angles of the best-fit planes and variance in the instantaneous curvature of the jaw-closing trajectories were evaluated. Pitch angles of the best-fit planes and curvature of the trajectories during closing in patients were more variable than those in control subjects (P < 0.05). After treatment, the variances decreased significantly (P < 0.05). These findings suggest that the achievement of good occlusion is associated with a reduction of variability of jaw movements in a gum-chewing task.
Laser Doppler flowmetry (LDF) is a non-invasive method to assess pulpal blood-flow (PBF). Dental injury has been associated with significant PBF reduction. The purpose of this study was to assess whether (i) the type of luxation trauma may affect PBF measurements and (ii) whether luxation type-related measurements may show short- and long-term changes of PBF values. In 41 trauma patients, 69 maxillary incisor treated by repositioning and splinting, and the respective contralateral homologous tooth were investigated by LDF to assess local PBF values. Perfusion units were recorded in four sessions, on the day of splint removal, and 12, 24 and 36 weeks after splint removal. Statistical analysis consisted of univariate analysis of variance for repeated measurements. For the LDF measurements, the main effect of the variable 'session' was not significant (P = 0.119). However, there was a significant 'session'/'luxation type' interaction (P = 0.000). Analysis of simple session-within-luxation type effects revealed intrusive luxations to be associated with a significant decrease in PBF values (P = 0.000), while subluxations (P = 0.568), lateral luxations (P = 0.980), extrusive luxations (P = 0.910), and avulsions (P = 0.996) showed no significant difference between session-related values. The PBF measurements did not change over time for the contralateral incisors (P = 0.996). The LDF may become useful in the detection of pulpal ischaemic episodes in luxated maxillary incisors after repositioning and splinting. Further studies are warranted to assess the validity of the diagnosis of post-traumatic 'ischaemic episodes' by comparing it with histological tooth pulp changes, and by determining how well it may predict course and response to treatments in clinical trials.
This study evaluated the fracture resistance of crown-restored incisors with different post-and-core systems and luting cements. Fifty intact maxillary central incisors were randomly assigned to five groups of 10 teeth each. Group 1 was restored with fibre posts (Snowpost) luted with an adhesive composite resin cement (Panavia F). Group 2 was restored with titanium alloy posts (Parapost) luted with the resin cement, and Group 3 with titanium alloy posts and a glass-ionomer cement (Fuji I). Composite cores (Clearfil Photocore) were built up in groups 1, 2 and 3. Group 4 was restored with cast post-and-cores luted with the resin cement, and group 5 with the cast post-and-cores and the glass-ionomer-cement served as a control group. All teeth were restored with metal-ceramic crowns. After thermal stressing, the specimen was then secured in a universal testing machine. Fracture loads and modes were recorded. One-way ANOVA and a Tukey test were used to determine significant differences between the failure loads of groups. Chi-square test was conducted for evaluation of the fracture modes. The fracture loads of groups 1 and 2 were significantly higher than that of the control group (P<0.05). Group 1 had a significantly higher number of repairable fractures than the other four groups (P<0.001). Within the limitations of this study, the results suggest that fibre posts can be recommended as an alternative to cast and prefabricated metallic posts. Composite resin cement cannot significantly improve fracture resistance of metallic post and crown-restored incisors.
A single mandibular incisor and an unusually narrow mandible and tongue were noted in an 8-year-old moderately retarded boy with 18p- (45, XY, der dic (18) (18qter-p11.2::22p 11.2-qter). While a single maxillary incisor, considered a minor feature of holoprosencephaly, was reported in three cases of 18p-, reduction of mandibular incisors has been a very rare finding and has never been noted in similar cases.
Mouse incisor tooth organs express the genes responsible for enamel extracellular matrix formation exclusively on the labial surface of the organ. A previous investigation has suggested that lingual inner dental epithelium of mouse incisor did not contain potential ameloblasts. The present work extends our histological observations, by analyzing the presence of mouse amelogenin mRNA in heterotopic mouse incisor tissue recombinations using in situ hybridization to 35S-labelled asymmetric complementary RNA probes from a cDNA specific to the mouse Mr 26 x 10(3) amelogenin. Labial polarized ameloblasts located in front of the lingual predentin layer were associated with numberous hybridization signals indicating an increased density of amelogenin mRNA. In contrast, the lingual inner dental epithelium in contact with labial predentin never showed amelogenin hybridization signals, indicating the absence of amelogenin transcripts. These results confirm our observation that the lingual inner dental epithelium does not contain potential ameloblasts, since these cells do not transcribe nor accumulate mRNA amelogenin even when in contact with a favorable microenvironment provided by the labial predentin.
Nerve growth factor (NGF), a target-derived neurotrophic substance, may have broader biological functions in various types of non-neuronal differentiating cells. The effects of NGF are dependent on initial binding of NGF to specific cell-surface receptors (p75NGFR and p140prototrk) on responsive cells. The continuously growing rat incisor offers an excellent model demonstrating defined territories of differentiation of specific cell populations. We used immunohistochemistry to determine sites of NGF, proNGF and p75NGFR accumulation in the rat incisor, whereas NGF mRNA expression was visualized by in situ hybridization in the developing rat molar and incisor. Strictly similar patterns of NGF mRNA, proNGF and NGF expression were observed in differentiating cells responsible for the production of the main structural matrices of the tooth. Thus, proNGF-like and NGF-like immunoreactivity, as well as the NGF mRNA signal were observed in preameloblasts and young ameloblasts of the dental epithelium and in polarizing odontoblasts of the dental mesenchyme. In contrast, the distribution of p75NGFR was correlated with differentiation event only in dental mesenchyme: polarizing odontoblasts expressed p75NGFR whereas the molecule was absent in functional odontoblasts. In dental epithelium, the restricted expression of p75NGFR in ameloblast precursor cells was correlated with proliferative phenomena. The patterns of proNGF, NGF and p75NGFR expression in epithelium and mesenchyme implicate both an autocrine and paracrine mode of action of the NGF molecule in dental tissues. The findings reported here are important for understanding NGF action in specific dental cell populations and suggest that this molecule is involved in the cascade of events that directs tooth development.
OBJECTIVES: The present study aimed at evaluating the marginal bone resorption and the peri-implant tissue conditions around Narrow-Neck ITI implants in the implant-prosthetic treatment of the agenesis of maxillary lateral incisors. MATERIAL AND METHODS: Thirty patients affected by monolateral or bilateral agenesis of the maxillary lateral incisors were selected. Thirty-four ITI-SLA Narrow Neck implants were inserted and loaded about 4 months after the surgical procedure. The final restorations were realized using Aureo Galvan Crowns veneered with feldspathic ceramics. The follow-up period ranged from 24 to 39 months. Both marginal bone resorption and soft tissue quality were evaluated. The data were statistically analysed using analysis of variance (ANOVA) for repeated measures, one-way ANOVA and Tukey's post hoc test (P=0.05). RESULTS: During the 24-39-month follow-up period, no implant showed either pain and sensitivity or mobility. After 39 months of functional loading, a cumulative survival rate of 97.06% and a cumulative success rate of 94.12% were calculated. CONCLUSIONS: In case of maxillary lateral incisor agenesis, the implant-prosthetic approach has proved to be a reliable and predictable treatment for both re-establishment of function and aesthetics. Satisfactory values of marginal bone resorption over time and optimal conditions of peri-implant tissue around Narrow-Neck ITI implants were found.
It has been suggested that the variation in the morphology of the human periodontium may be related to the shape and form of the teeth. Furthermore, the severity of symptoms of periodontal disease have been proposed to differ among these various morphologic entities or "biotypes". The aim of the present study was (i) to identify individuals with markedly different crown forms and (ii) to determine probing pocket depth, probing attachment level and amount of gingival recession that had occurred at different teeth and tooth surfaces in such individuals. Clinical photographs of the maxillary incisor tooth region of 113 subjects who had been recruited for a long-term study on periodontal disease were available. The length (CL) and width (CW) of the crowns were determined and the CW/CL ratio was calculated for each tooth. 10% in each tail, 11 subjects in each group, were arbitrarily chosen as having either a long-narrow (N) or a short-wide (W) form of the central incisors. The probing pocket depth, probing attachment level and gingival recession data available from all subjects and subjects in groups W and N were compared and analyzed using the Student t-test and multiple regression analysis. The result from the analyses demonstrated that: (1) subjects with a long-narrow form of the upper central incisors had experienced more recession of the gingival margin at buccal surfaces than subjects who had a short-wide tooth form; (2) there was a significant influence of the CW/CL-ratio on the probing attachment level (p less than 0.05) and the amount of gingival recession (p less than 0.01) on buccal tooth surfaces.(ABSTRACT TRUNCATED AT 250 WORDS)
28 children aged 6-13 years, with gingival recession localized to mandibular incisors, were monitored longitudinally to evaluate any changes of the labial periodontal tissues. Measurements included dental plaque, gingival inflammation, gingival recession, probing depth, probing attachment level, keratinized and attached gingiva. Following baseline examination, the incisors were observed at yearly intervals over 3 years. The results showed that a high level of oral hygiene was maintained and that gingival inflammation occurred only to a minor degree throughout the observation period. Gradual reductions in the amount of gingival recession and probing attachment levels took place in all children except for 1 of the subjects with 1 severely malpositioned tooth. Probing depths and widths of keratinized and attached gingiva remained relatively unchanged. The finding that gingival recession in mandibular incisors in young children often improves over time suggests that preventive or reparative treatment in this part of the developing dentition may not be necessary. Decisions about such treatment should be postponed until any spontaneous improvement has taken place.
1,159 children (612 girls and 547 boys) aged 11-12 years were examined to determine the range and mean overjet values in four defined upper lip-maxillary central incisor relationships. No clinically significant differences were found on comparison of the data relative to each upper lip position. The findings suggest that upper lip posture is adaptive to the maxillary central incisor angulation and that the upper lip musculature is unlikely to influence the development of the incisor occlusion.
117 children who had experienced trauma to their primary incisors were re-examined in their transitional or permanent dentition stage. The control group consisted of 174 children with a corresponding dental developmental age. All the children were examined clinically and the intra- and interarch relations of the anterior segments were recorded. The prevalence of patients with at least one malposed incisor was higher in the trauma group. Trauma to the primary dentition was found to be a contributing factor affecting the alignment of the permanent successors. Early loss of the primary incisors did not cause loss of space in most of the cases; however, it was associated with malposition of their permanent successors. Lack of eruption guidance or the direct effect of the injury on the position of the developing bud could be considered as contributing etiologic factors. There was a very low prevalence of more serious malocclusion features, like impaction, in the trauma group.
A radiographic survey of a random sample of 454 girls aged 5.9 +/- 0.5 yr and 521 boys aged 5.8 +/- 0.4 y was undertaken to establish data on the incidence of congenitally missing mandibular incisor teeth amongst the Southern Chinese and to compare these figures with those of a similar previous study of 12-yr-olds so to eliminate factors such a trauma or extractions which may have artificially inflated the 12-yr-old incidence data. The proportion of 5-yr-old girls and boys affected by hypodontia in the permanent mandibular incisor region was 0.086 and 0.046 respectively (a significant difference between sexes, P < 0.02), compared with 0.047 and 0.034 for the 12-yr-olds (a non-significant difference) so other factors must have contributed to the discrepancy between the two groups of children. A very strong correlation (P < 10(-25)) between missing primary and missing permanent mandibular incisors is present in this group, and this has implications for prognosis and treatment planning. A fundamental developmental defect is implied.
Permanent incisors from fetal New Zealand white rabbits aged 27-29 in utero from offspring of New Zealand white rabbits until the 4th d after parturition were processed for scanning electron microscopy. Macroscopic examination and measurements on standardized scanning electron micrographs revealed that the lingual surface of unerupted teeth was covered with developing enamel extending about 2.1 mm from the incisal end as evidenced by the presence of typical Tomes' pits. Such structures were not observed more apically where the lingual tooth surface appeared to be covered by cementum. The permanent incisors erupted into the oral cavity at birth and attrition was initiated within a few hours after parturition, leading to an inverse correlation between attritional loss of tooth substance and extension of lingual enamel. The findings indicate that the enamel-covered, linguoincisal part of the rabbit permanent incisors is not a root-analogue surface. The results are discussed in the light of recent studies on rabbits and rodents.
Permanent incisors from fetal New Zealand white rabbits aged 25-30 d in utero were processed for light microscopy. Examination of transverse and longitudinal sections of demineralized specimens revealed the development of a complete enamel covering of the incisal tip and an enamel extension on the linguoincisal surface of unerupted teeth, as evidenced by the presence and distribution of ameloblasts, enamel matrix and enamel space. Formation of lingual enamel appeared to be completed within a few days before eruption of the incisor. The transition from the enamel-covered to enamel-free areas coincided with a gradual disintegration of the orderly ameloblast layer. The findings indicate that, histologically, the linguoincisal part of the rabbit permanent incisor is characterized by amelogenesis.