Evaluation of enamel thickness of mandibular incisors

ABSTRACT Objective: To measure enamel thickness at the proximal surfaces of the mandibular incisors, using micro-computed tomography (micro-CT) scans. Material and Methods: Forty-one single-rooted mandibular incisors were selected and analyzed according to anatomical characteristics, to form three groups: Group 1 - central incisors (n = 18); Group 2 - right lateral incisors (n = 10); and Group 3 - left lateral incisors (n = 13). First, enamel thickness at the proximal contact areas of the mandibular incisors was measured. Second, the mesial and distal surfaces of the lateral incisors were compared. Finally, the relationship between the tooth width and the mean enamel thickness was determined. Each tooth was scanned with a micro-CT scanner, and the image was processed with SCANCO micro-CT onboard analysis software. Results: There were no statistically significant differences in mean enamel thickness between the mesial and distal surfaces for each lateral incisor, or between contralateral lateral incisors. In all surfaces analyzed, the upper zones had statistically significantly thinner enamel (0.52 ± 0.10 mm) when compared to the middle and lower zones (0.60 ± 0.08 mm and 0.59 ± 0.08 mm, respectively). There was no correlation (r =0.07) between enamel thickness of the mandibular incisor and the tooth width. Conclusions: The enamel thickness of the mandibular incisors is similar on the mesial and distal surfaces, with the thinnest layer located at the upper zone.

RESUMO Objetivo: Medir a espessura do esmalte nas superfícies proximais dos incisivos inferiores, usando imagens de microtomografia computadorizada (micro-CT). Material e Métodos: Quarenta e um incisivos inferiores com raiz única foram selecionados e analisados de acordo com as características anatômicas, formando três grupos: Grupo 1 - incisivos centrais (n = 18); Grupo 2 - incisivos laterais direitos (n = 10); e Grupo 3 - incisivos laterais esquerdos (n = 13). Primeiro, foi medida a espessura do esmalte nas áreas de contato proximal dos incisivos inferiores. Em segundo lugar, as faces mesial e distal dos incisivos laterais foram comparadas. Por fim, foi determinada a relação entre a largura do dente e a espessura média do esmalte. Cada dente foi escaneado com um scanner micro-CT, e a imagem foi processada com o software de análise SCANCO micro-CT. Resultados: Não houve diferenças estatisticamente significativas na espessura média do esmalte entre as superfícies mesial e distal de cada incisivo lateral, ou entre os incisivos laterais contralaterais. Em todas as superfícies analisadas, as zonas superiores apresentaram esmalte significativamente mais fino (0,52 ± 0,10 mm) quando comparadas às zonas média e inferior (0,60 ± 0,08 mm e 0,59 ± 0,08 mm, respectivamente). Não houve correlação (r = 0,07) entre a espessura do esmalte do incisivo inferior e a largura do dente. Conclusões: A espessura do esmalte dos incisivos inferiores é semelhante nas faces mesial e distal, com a camada mais fina localizada na zona superior.

Expecting The Unexpected

Report of unusual presentation of two root canals in all the mandibular anterior teeth in a single patient.Incidence of two canals in individual mandibular anterior teeth ranges from 5-37% but all six anterior teeth showing two canals is a rare finding and is seen in less then 5% of the population. We report Endodontic management of such case. Conclusion:Successful endodontic therapy of a tooth demands that a dentist should have a thorough knowledge of the root canal morphology, making it mandatory towards proper radiographic evaluation and diagnosis of the status of the pulp canals as well as periapical areas. Improper diagnostic protocol may lead to failure of Endodontic treatment. The case presented here shows successful root canal treatment of all the mandibular anterior teeth with two root canals each. The frequency of mandibular anterior teeth havingtwo root canals varies from 5% to 37 % in different populations.Pulp space anatomy of mandibular anterior teeth shows high incidence of complexity which includes variation in canal configurations, number of canals and presence of isthmus. Thorough knowledge of root canal anatomy and morphology, additional radiographs taken at different angles and correct interpretation of radiographs is mandatory

Application of strip crown form in aesthetic restoration of mandibular deciduous incisors in severe childhood caries / 中华医学美学美容杂志

Objective To explore the feasibility and effectiveness of aesthetic restoration of caries of mandibular deciduous incisors with strip crown form of maxillary deciduous incisors.Methods A total of 64 patients (202 teeth) with symmetrical caries of bilateral mandibular central incisors or lateral incisors were randomly selected.The opposite maxillary incisors were restored with strip crowns form and the opposite incisors were restored with resin composite.The effects of the two methods and the incidence of complications were compared three months,six months and twelve months after treatment.Results Three months after treatment,there was no significant difference in the success rate between the two groups.Six months after treatment,there was significant differencein the marginal adaptation between the two groups (x2 =3.919,P =0.048);12 months after treatment,there was significant difference in the restoration integrity of the two groups and the incidence of secondary caries (x2 =5.027,P =0.025;secondary caries x2 =4.369,P =0.037).Conclusions The strip crown form of maxillary primary incisors can be used for aesthetic restoration of caries of mandibular primary incisors,and its effect is better than that of direct resin filling.The strip crown form for mandibular primary incisors needs to be developed and produced urgently.

Facial profile of patients with congenitally missing 2 mandibular incisors and changes of facial profile before and after orthodontic treatment by extraction of 2 maxillary premolars / 吉林大学学报(医学版)

Objective: To analyze the facial profile of the patients with congenitally missing 2 mandibular incisors, and to investigate the changes of facial profile of the patients before and after orthodontic treatment by extraction of 2 maxillary premolars. Methods: The cephalometrics of 64 patients with congenitally missing 2 mandibular incisors were collected. The initial cephalometrics of 64 patients were used to characterize the facial profile. A total of 38 cases among all the 64 patients underwent the orthodontic treatment by extraction of 2 maxillary premolars, and the initial and final cephalometrics were used to compare the changes of facial profile before and after treatment. The cephalometric measurement (including hard tissue and soft tissue items) was performed and the results were analyzed statistically. Results: Compared with the normal values, the overjet, overbite, ANB, U1-NA angle, face angle, Y axis, Pg-NB, face convexity, soft tissue facial angle, H angle, and men to labial sulcus to H-Line in the patients with congenitally missing 2 mandibular incisors were increase d, SNB, L1-NB angle, L1-NB distance, L1-MP, occlusal plane angle, mentolabial sulcus angle were decreased, and the differences were statistically significant (P<0. 05). After orthodontic extraction treatment, the overjet, overbite, U1-NA angle, U1-NA distance, U1-SN, H angle, and subnasale to H-Line of the patients were decreased, the L1-NB angle, L1-NB distance, L1-MP, occlusal plane angle, Pg-NB, and mentolabial sulcus angle were increased; the differences were statistically significant (P<0. 05). Conclusion: The mandibular development is insufficient but the chin development is adequate in the patients with congenitally missing 2 mandibular incisors, with larger overjet and overbite, lingually inclined mandibular incisors, deeper and sharper mentolabial sulcus. After treatment by extraction of 2 maxillary premolars, the overall appearance of the lateral profile of the patients remains unchanged, but the occlusion of anterior teeth is significantly improved.

Bilateral Mandibular Centrals with Rare Type IV Canals

The aim of this study was to report the endodontic management of maxillary incisors having two canals with rare type IV vertucci canal configuration. Internal morphology of root canals is variable and often complex. Therefore, to achieve a technically satisfactory endodontic outcome, the clinician must have an adequate knowledge of the internal canal morphology and its variations to debride and obturate the root canal system thoroughly. This case report describes the successful endodontic treatment of both the mandibular central incisors having two-root canals in same individual.

Relating Mandibular Incisor to the Lingual Frenum in Dentulous and Edentulous (Complete Denture Wearers) Subjects: An in vitro Study.

Aim and Objectives: This study is determined the vertical distance between lingual frenum and incisal edge of mandibular central incisors in dentulous subject and edentulous denture wearer subjects and their variation in different age groups and sex. Materials and Methods: This study involved 120 dentulous subjects (60 men, 60 women) and 20 complete denture wearers. Depending upon the age, the dentulous subjects were divided into three groups. Each group consisted of 40 subjects (20 men, 20 women). Group I consisted of 20-30 yr age, group II 30-4 0yr age and group III consisted of more than 40 yr age. Mandibular impressions of dentulous and denture wearers were made with irreversible hydrocolloid and cast retrieved. The vertical distance between the anterior attachment of lingual frenum and incisal edges of the mandibular central incisors for both the dentulous and edentulous subjects was measured on the casts with the help of dental surveyor. Data were tabulated and stastically analysed. Results: Overall (irrespective of gender) normative range for vertical distance between the anterior attachment of the lingual frenum and mesioincisal edge of mandibular central incisor among dentulous subjects is 9.52-10.24 mm. If we consider gender it is 10.00-11.13 mm for male and 8.82-9.58 mm for female. Conclusion: This study indicated that the distance between the antero-superior most point on the lingual frenum and the mesio-incisal edges of mandibular central incisors can be used as a reliable landmark when the frenum is recorded during function.

Study of root canal morphology of mandibular incisors by micro-computed tomography in vitro / 实用口腔医学杂志

Objective:To investigate the anatomy of mandibular incisors using microcomputed tomography(Micro-CT).Methods:62 extracted mandibular incisors were selected from dental clinic and observed by Micro-CT.The anatomy of the teeth was analyzed. Results:83.9% of mandibular incisors had a single canal,72.6% had no accessory canal.The location of the apical foramen varied considerably.The mean distance from the root apex to the major lateral apical foramen was (0.613 ±0.298)mm.Of the canals the bucco-lingual diameter were greater than the mesio-distal diameters and the root bucco-lingual canal tapers were greater than the me-sio-distal.Conclusion:The morphology data of mandibular incisors were obtained using Micro-CT.

Non-syndromic oligodontia in permanent dentition: a rare case report / Oligodontia não sindrômica nad entição permanente: relato de caso raro

Tooth agenesis is one of the most common congenital anomalies seen in humans. Although absence of one or more teeth is common, absence of multiple teeth is rare. Oligodontia is a rare developmental anomaly, involving agenesis of six or more permanent teeth, excluding the third molars. The reported prevalence of oligodontia in permanent dentition is 0.14%. Oligodontia can be presented as an isolated condition or as a part of a syndrome. Discussion: The present case report highlights a unique case of non-syndromic oligodontia, with agenesis of four permanent incisors, left permanent canine and right second premolar in the mandibular arch and its management with a novel fixed functional prosthetic appliance. Conclusion: Prosthetic rehabilitation is an urgent need for these kind of patients so that they do not suffer from masticatory and esthetic problems which can eventually lower the self esteem of individuals...

A agenesia dentária é uma das anomalias congênitas mais comuns em humanos. Embora a ausência de um ou mais dentes seja comum, a ausência de vários dentes é rara. A oligodontia é uma anomalia de desenvolvimento rara, envolvendo agenesia de seis ou mais dentes permanentes, excluindo os terceiros molares. A prevalência de oligodontia na dentição permanente é de 0,14%. A oligodontia pode apresentar-se como uma condição isolada ou como parte de uma síndrome. Discussão: O presente relato destaca um caso único de oligodontia não sindrômica, com agenesia de quatro incisivos permanentes, canino permanente esquerdo e segundo pré-molar direito no arco inferior, e seu manejo com um novo aparelho de prótese fixa funcional. Conclusão: A reabilitação protética é uma necessidade urgente para este tipo de paciente para que ele não sofra de problemas de mastigação e estética, os quais podem eventualmente reduzir a autoestima do indivíduo...

Prevalence of two root canals in human mandibular anterior teeth in an Iranian population.

Background: Complete debridement and obturation of the root canal system is a key factor in successful endodontic treatment and the operator should therefore have thorough knowledge of the root canal morphology of the teeth. Numerous studies have been carried out to investigate the canal configuration of different tooth types in various populations. Aims: The aim of the present study was to investigate the internal anatomy of mandibular incisors and canines in an Iranian population. Materials and Methods: A total of 463 mandibular anterior teeth, including 186 centrals, 128 laterals, and 149 canines, were examined. A standard clearing technique was used to make the teeth transparent. India ink was injected into the canals of the teeth and the samples were examined with a magnifying glass. The root canal configurations were categorized according to the Vertucci classification. Results: All the incisors in this study had one root, and 12.08% of the canines had two roots. We found a slightly higher prevalence of the second canal in incisors than in canines (36.62% vs. 20.48%). However, the probability of canines having two separate apical foramina was higher than that for incisors (12.08% vs. 0.64%). Conclusions: In view of the high prevalence of two-canaled mandibular anterior teeth found in this study, it would be prudent to assume that any mandibular anterior tooth being treated is two-canaled until a thorough search proves otherwise.

In vitro incidence of root canal bifurcation in mandibular incisors by radiovisiography

Objective: The aim of this study was to verify, in vivo and in vitro, the prevalence of root canal bifurcation in mandibular incisors by digital radiography. Material and Methods: Four hundred teeth were analyzed for the in vivo study. Digital radiographs were taken in an orthoradial direction from the mandibular incisor and canine regions. The digital radiographs of the canine region allowed visualizing the incisors in a distoradial direction using 20o deviation. All individuals agreed to participate by signing an informed consent form. The in vitro study was conducted on 200 mandibular incisors positioned on a model, simulating the mandibular dental arch. Digital radiographs were taken from the mandibular incisors in both buccolingual and mesiodistal directions. Results:The digital radiography showed presence of bifurcation in 20% of teeth evaluated in vitro in the mesiodistal direction. In the buccolingual direction, 17.5% of teeth evaluated in vivo and 15% evaluated in vitro presented bifurcation or characteristics indicatingbifurcation. Conclusions: Digital radiography associated with X-ray beam distally allowed detection of a larger number of cases of bifurcated root canals or characteristics of bifurcation.