Prenatal Correction of X-Linked Hypohidrotic Ectodermal Dysplasia.

Genetic deficiency of ectodysplasin A (EDA) causes X-linked hypohidrotic ectodermal dysplasia (XLHED), in which the development of sweat glands is irreversibly impaired, an condition that can lead to life-threatening hyperthermia. We observed normal development of mouse fetuses with Eda mutations after they had been exposed in utero to a recombinant protein that includes the receptor-binding domain of EDA. We administered this protein intraamniotically to two affected human twins at gestational weeks 26 and 31 and to a single affected human fetus at gestational week 26; the infants, born in week 33 (twins) and week 39 (singleton), were able to sweat normally, and XLHED-related illness had not developed by 14 to 22 months of age. (Funded by Edimer Pharmaceuticals and others.).

Reliability of prenatal detection of X-linked hypohidrotic ectodermal dysplasia by tooth germ sonography.

OBJECTIVE: In X-linked hypohidrotic ectodermal dysplasia (XLHED), dysfunction of ectodysplasin A1 (EDA1) due to EDA mutations results in malformation of hair, teeth, and sweat glands. Hypohidrosis, which can cause life-threatening hyperthermia, is amenable to intrauterine therapy with recombinant EDA1. This study aimed at evaluating tooth germ sonography as a noninvasive means to identify affected fetuses in pregnant carrier women. METHODS: Sonography, performed at 10 study sites between gestational weeks 18 and 28, led to the diagnosis of XLHED if fewer than six tooth germs were detected in mandible or maxilla. The assessment was verified postnatally by EDA sequencing and/or clinical findings. Estimated fetal weights and postnatal weight gain of boys with XLHED were assessed using appropriate growth charts. RESULTS: In 19 of 38 sonographic examinations (23 male and 13 female fetuses), XLHED was detected prenatally. The prenatal diagnosis proved to be correct in 37 cases; one affected male fetus was missed. Specificity and positive predictive value were both 100%. Tooth counts obtained by clinical examination corresponded well with findings on panoramic radiographs. We observed no weight deficits of subjects with XLHED in utero but occasionally during infancy. CONCLUSION: Tooth germ sonography is highly specific and reliable in detecting XLHED prenatally.

Two-Dimensional Identification of Fetal Tooth Germs.

OBJECTIVE: To demonstrate the efficiency and applicability of two-dimensional ultrasonography in the identification of tooth germs and in the assessment of potential pathology. DESIGN: Observational, descriptive, cross-sectional study. SETTING: Prenatal Diagnosis Unit of Centro Hospitalar de Vila Nova de Gaia / Espinho-Empresa Pública in Portugal. PATIENTS: A total of 157 white pregnant women (median age, 32 years; range, 14 to 47 years) undergoing routine ultrasound exams. MAIN OUTCOME MEASURE(S): Description of the fetal tooth germs, as visualized by two-dimensional ultrasonography, including results from prior fetal biometry and detailed screening for malformations. RESULTS: In the first trimester group, ultrasonography identified 10 tooth germs in the maxilla and 10 tooth germs in the mandible in all fetuses except for one who presented eight maxillary tooth germs. This case was associated with a chromosomal abnormality (trisomy 13) with a bilateral cleft palate. In the second and third trimesters group, ultrasonography identified a larger range of tooth germs: 81.2% of fetuses showed 10 tooth germs in the maxilla and 85.0% of fetuses had 10 tooth germs in the mandible. Hypodontia was more prevalent in the maxilla than in the mandible, which led us to use qualitative two-dimensional ultrasonography to analyze the possible association between hypodontia and other variables such as fetal pathology, markers, head, nuchal, face, and spine. CONCLUSIONS: We recommend using this method as the first exam to evaluate fetal morphology and also to help establish accurate diagnosis of abnormalities in pregnancy.

Determination of the mesio-distal tooth width via 3D imaging techniques with and without ionizing radiation: CBCT, MSCT, and µCT versus MRI.

Objective: The purpose of this study was to estimate the feasibility and accuracy of mesio-distal width measurements with magnetic resonance imaging (MRI) in comparison to conventional 3D imaging techniques [multi-slice CT (MSCT), cone-beam CT (CBCT), and µCT]. The measured values of the tooth widths were compared to each other to estimate the amount of radiation necessary to enable orthodontic diagnostics. Material and Methods: Two pig skulls were measured with MSCT, CBCT, µCT, and MRI. Three different judges were asked to determine the mesio-distal tooth width of 14 teeth in 2D tomographic images and in 3D segmented images via a virtual ruler in every imaging dataset. Results: Approximately 19% (27/140) of all test points in 2D tomographic slice images and 12% (17/140) of the test points in 3D segmented images showed a significant difference (P ≤ 0.05). The largest significant difference was 1.6mm (P < 0.001). There were fewer significant differences in the measurement of the tooth germs than in erupted teeth. Conclusions: Measurement of tooth width by MRI seems to be clinically equivalent to the conventional techniques (CBCT and MSCT). Tooth germs are better illustrated than erupted teeth on MRI. Three-dimensional segmented images offer only a slight advantage over 2D tomographic slice images. MRI, which avoids radiation, is particularly appealing in adolescents if these data can be corroborated in further studies.

Surgical Template to Minimize the Damage of Tooth Buds in Young Children With Mandibular Distraction Osteogenesis.

BACKGROUND: Mandibular distraction osteogenesis has become one of the most powerful reconstructive techniques for the treatment of mandibular deformities in young children. Damage to the tooth buds is often cited as a complication of it. The purpose of this study was to precisely design the osteotomy line and avoid the damage of tooth buds at the mandibular angle area with the help of surgical template. METHODS: Six patients aged from 6 to 10 years were selected in this study. Three-dimensional computed tomography data was put into Mimics software for preoperative planning the osteotomy line and the accurate placement of the distractor based on the exact position of tooth follicle. And then the surgical template was manufactured by a three-dimensional printer with rapid prototyping technique. The surgeons were guided to perform the osteotomy aided with the prefabricated template through an intraoral approach. Distraction began 7 days postoperation with a rate of 1 mm/d and the distractor was removed after a 6 to 8 months consolidation period. The tooth buds were observed through radiographs that were performed at 5 time intervals: before distraction, at the end of latency, at the end of distraction, at the end of consolidation and 2 years of the postoperation to remove the distractor. RESULTS: The average follow-up time is 24 months. Facial appearance and occlusal plane of all the young patients were greatly improved without complications. From the radiological observation, the tooth buds was intact after the surgery and the second molar normally erupted after removing the distractor. CONCLUSIONS: The surgical template was considered to be helpful in improving the surgical accuracy and avoiding the tooth buds damage during mandibular distraction osteogenesis.

Cone-Beam Computed Tomography Study Of Crown Dilaceration With a Talon Cusp in an Unerupted Permanent Maxillary Tooth.

This article describes a rare case of crown dilaceration with a talon cusp in an unerupted permanent maxillary central incisor. Our patient was a 7-year-old boy with a history of trauma to his primary maxillary teeth (#51 and 52), at 3 years of age complaining of failure of eruption of tooth #11. Periapical radiography showed incomplete formation of tooth root #11 and more superior position of tooth bud #11 relative to tooth bud #12. A cone-beam computed tomography was ordered, which revealed crown dilaceration with a talon cusp in tooth bud #11. The patient was scheduled for follow-up at 6 months.

Noninvasive Prenatal Diagnosis of Hypohidrotic Ectodermal Dysplasia by Tooth Germ Sonography.

PURPOSE: Hypohidrotic ectodermal dysplasia, a potentially life-threatening heritable disorder, may be recognized already in utero by characteristic features such as oligodontia and mandibular hypoplasia. As therapeutic options and prognosis depend on the time point of diagnosis, early recognition was attempted during routine prenatal ultrasound examinations. SUBJECTS AND METHODS: Fetuses of nine pregnant women (one triplet and eight singleton pregnancies) with family histories of hypohidrotic ectodermal dysplasia were investigated by sonography between the 20th and 24th week of gestation. RESULTS: In 4 male and 2 female fetuses reduced amounts of tooth germs were detected, whereas 5 fetal subjects showed the normal amount. Three-dimensional ultrasound evaluation revealed mandibular hypoplasia in 5 of the 6 fetuses with oligodontia. Molecular genetic analysis and/or clinical findings after birth confirmed the prenatal sonographic diagnosis in each subject. CONCLUSION: In subjects with a family history of hypohidrotic ectodermal dysplasia, the diagnosis of this rare condition can be established noninvasively by sonography in the second trimester of pregnancy. Early recognition of the disorder may help to prevent dangerous hyperthermic episodes in infancy and may allow timely therapeutic interventions.

Fast and Early Mandibular Osteodistraction: The Long-Term Follow-Up of Mandibular Distraction Osteogenesis on Teeth Position.

Pierre Robin Sequence is a congenital pathology defined by the triad micrognathia, glossoptosis and often a U-shaped cleft of soft palate. Newborns affected by airways obstruction may necessitate more invasive options: tongue-lip adhesion, tracheostomy and mandibular distraction osteogenesis. The authors analyzed the effect of fast and early mandibular osteodistraction on deciduous dental development in patients affected by Pierre Robin Sequence. Analysis of the patients treated for severe form was performed by a team composed by maxillofacial surgeons and dentists. Five patients were included for the analysis: before and long term clinical and radiological assessments were considered. All patients underwent fast and early mandibular osteodistraction; two years follow up computed tomography and panorex reconstructions showed bone consolidation, 33 of 35 teeth analyzed before ostedistraction are present after distraction protocol; no positional changes were detected at the follow up analysis either deciduous teeth and molar permanent buds. No deformities regarding molar buds were detected. In conclusion external mandibular distractor devices have been associated with dental injuries and facial scaring. Even though, the dental complications identified can not be unambiguously connected to the external distractor devices.

Association between mesially displaced maxillary first premolars and early displaced maxillary canines.

AIM: To evaluate the association between the mesially displaced maxillary first premolar (MDP) and the early displacement of the adjacent permanent canine (EDC) before their eruption. MATERIALS AND METHODS: A sample of 1247 subjects in the intermediate mixed dentition stage was assessed for the presence of MDP and EDC. All subjects were divided into two groups: MDP group and noMDP group. For each subject two angular measurements (premolar-occlusal plane η and л premolar-midline angles) were analysed on panoramic radiographs. The chi-square test with Yates correction was performed to compare the prevalence rate of EDC in MDP (MDP-EDC) and noMDP groups. The statistical comparisons for the values of η and л angles between MDP vs noMDP, MDP vs MDP-EDC, and noMDP vs MDP-EDC groups were performed by means of ANOVA with Bonferroni correction. RESULTS: The prevalence rate of EDC in the MDP group was significantly greater than in the noMDP group (66% vs. 12.1%). MDP-EDC group showed a significantly larger л angle than in the MDP group resulting in an increased mesial inclination of displaced premolars. CONCLUSION: MDP can be considered a dental anomaly associated to maxillary canine displacement.

Fetal age estimation using MSCT scans of deciduous tooth germs.

Evaluation of fetal age is an essential element in many fields such as anthropology, odontology, paleopathology, and forensic sciences. This study examines the correlation between fetal age, femoral diaphyseal length (considered as the gold standard), and deciduous tooth germs of fetuses aged 22 to 40 weeks amenorrhea (WA) based on computed tomography (MSCT) reconstructions. Qualitative and quantitative studies of femoral and deciduous tooth germ lengths were performed on 81 fetuses (39 females and 42 males). R software was used for statistical analyses. Intra-observer and inter-observer variabilities and the interclass correlation coefficient (ICC) were calculated. Correlation coefficients (R (2)) and linear regression equations were calculated. Intra- and inter-observer variabilities were very satisfactory (intra-observer ICC ≥ 0.96, inter-observer ICC ≥ 0.95). Femoral length was significantly correlated with age (R (2) = 0.9). The correlation coefficient between age and height, width, and dental volume was R (2) ≥ 0.73. Tooth germs were good indicators of fetal age. Our method appears to be reliable and reproducible, and the results of this study agreed with those of the literature. The dental formula provided a precise estimation of fetal age between 25 and 32 WA. Tooth germs were reliable indicators of fetal age, and multislice computed tomography was shown to be an innovative and reliable technology for this purpose.

Tooth pattern, development, and replacement in the yellow catfish, Pelteobagrus fulvidraco.

Studies of teleost teeth are important for understanding the evolution and mechanisms of tooth development, replacement, and regeneration. Here, we used gross specimens, microcomputed tomography, and histological analysis to characterize tooth structure, development, and resorption patterns in adult Pelteobagrus fulvidraco. The oral and pharyngeal teeth are villiform and conical. Multiple rows of dentition are densely distributed and the tooth germ is derived from the epithelium. P. fulvidraco exhibits a discontinuous and non-permanent dental lamina. Epithelial cells surround the teeth and are separated into distinct tooth units by mesenchymal tissue. Tooth development is completed in the form of independent tooth units. P. fulvidraco does not undergo simultaneous tooth replacement. Based on tooth development and resorption status, five forms of teeth are present in adult P. fulvidraco: developing tooth germs, accompanied by relatively immature tooth germs; mature and well-mineralized tooth accompanied by one tooth germ; teeth that have begun resorption, but not completely fractured; fractured teeth with only residual attachment to the underlying bone; and teeth that are completely resorbed and detached. Seven biological stages of a tooth in P. fulvidraco were also described.

Single tooth odontodysplasia. Case report.

Odontodysplasia (ghost tooth) is an uncommon, nonhereditary developmental condition of unknown origin, affecting both mesodermal and ectodermal elements of the dental organ. To our knowledge, this case is unique in that it is only the second reported case of odontodysplasia affecting a single tooth. Based on clinical, radiographic and histologic findings, we diagnosed this tooth as a ghost tooth.

Radiographic study of delayed tooth development in patients with dental agenesis.

INTRODUCTION: The aims of this study were to compare the radiographic development of permanent teeth in a group of children affected by dental agenesis with an unaffected control group and to determine the effects of confounding factors including the severity of the dental agenesis, age, sex, ethnicity, and the number of stages used to estimate dental age. METHODS: A single-center retrospective cross-sectional study of dental panoramic tomographs was undertaken between July 2007 and April 2008 in a postgraduate teaching school. A total of 139 patients (aged 9-18 years) were recruited from the orthodontic clinic on the basis of predetermined inclusion and exclusion criteria to either a dental agenesis group or a control group. Dental panoramic tomograms were assessed, and the stages of development of the permanent teeth in the left maxillary and left mandibular regions were scored by using the 12 stages of Haavikko and the 8 stages of Demirjian and Goldstein. For each tooth scored, the mean dental age and standard error were determined by using the dental age assessment method, and an estimated dental age for each subject was derived by using the weighted average method. RESULTS: A statistically significant delay in dental age was found in the patients with dental agenesis compared with the control group. The dental age assessment method of Haavikko showed a delay of 1.20 years (SD, 1.74), and the method of Demirjian and Goldstein showed a delay of 1.64 years (SD, 1.75). It was also observed that older patients with dental agenesis had greater delays in tooth formation (P <0.001). With the Haavikko method, for every year of chronologic age, the delay in dental age increased by 0.53 year; with the Demirjian and Goldstein method, the delay increased by 0.48 year. A significant association was seen between the severity of dental agenesis and the delay in dental age (P <0.01). With both methods, for each additional developmentally absent tooth, the dental age was delayed by 0.13 year (lower confidence interval, -0.22; upper confidence interval, 0.35). There was no evidence that sex or ethnicity has an effect on the delay in dental age in patients with dental agenesis. CONCLUSIONS: The development of permanent teeth in children with dental agenesis is delayed when compared with a matched control group. The severity of dental agenesis affected the magnitude of the delay (P <0.01). This delay has implications in orthodontic treatment planning and in the estimation of age for legal, immigration, archaeological, and forensic purposes.

Uprighting of severely impacted mandibular second molars: a case report.

INTRODUCTION: The incidence of mandibular first and second molar impaction is increasing but still recorded as rare. Treatment methods involving uprighting, extraction, or autologous tooth transplantation have been described. AIM: The present study describes the uprighting of 3 impacted mandibular second molars presenting with eruptive disorders. METHODS: The application of limited and appropriate orthodontic therapy completed treatment in 11 months, 5 months, and 2 years and 3 months, respectively. Although no absolute anchorage in the form of miniscrews was required, no significant anchorage demands were considered necessary. Although the third molar tooth germs were identified and preserved in each case, no adverse influence on the uprighting of the second molars was encountered. RESULTS: The favourable molar repositioning results were likely due to the youth of the 3 patients as the third molars were in early development and bone remodelling was marked. Furthermore, no problems related to anchorage or alveolar bone loss were identified after treatment. CONCLUSION: The results indicated the benefits of limited orthodontic treatment and early intervention for the uprighting of impacted mandibular second molars.

Supernumerary teeth in patients with cleft lip and palate: the tooth germs do not separate.

INTRODUCTION: Supernumerary teeth in cases of cleft lip and palate do not result from the division of normal germs before the formation of hard tissue. Deciduous and permanent teeth odontogenesis begins after the face has formed, either with or without the cleft. DISCUSSION: The most acceptable hypothesis to enable understanding of the presence of supernumerary teeth on one or both sides of the cleft palate is hyperactivity of the dental lamina in its walls. This hyperactivity, with the formation of more tooth germs, must be attributed to mediators and genes related to tooth formation, under strong influence of local epigenetic factors, whose developmental environment was affected by the presence of the cleft. CONCLUSION: The current concepts of embryology no longer support the fusion of embryonic processes for the formation of the face, but rather the leveling of the grooves between them. All human teeth have a dual embryonic origin, as they are composed of ectoderm and mesenchyme/ectomesenchyme, but this does not make it easy for them to be duplicated to form supernumerary teeth.

Distally displaced premolars: A dental anomaly associated with palatally displaced canines.

INTRODUCTION: The aim of this study was to evaluate the significance of association between distally displaced premolars (DDP) and palatally displaced canines (PDC) in the pattern of associated phenotypes of dental developmental disturbance. METHODS: A sample of 2811 subjects (mean age, 9 years 7 months +/- 1 year 3 months) was divided randomly into 2 groups. The first group of 500 subjects was the control group. The reference prevalence rates for the examined parameters were calculated for this group: DDP (measured with the distal angle theta and the premolar-molar angle gamma); PDC; and other dental anomalies, specifically, aplasia of the third molars, aplasia of the contralateral mandibular second premolar, aplasia of the maxillary lateral incisors, and small maxillary lateral incisors. Of the remaining 2311 subjects, the first 100 with a diagnosis of DDP of at least 1 mandibular second premolar comprised experimental group 1 (DDP group). In addition to sex distribution, the same variables that were examined in the control group were analyzed. In the subgroup with the concurrent DDP and PDC (experimental group 2, or DDP-PDC group), the presence of other dental anomalies was investigated. The prevalence rate for PDC in experimental group 1 was compared with that in the control group. The same was done for the prevalence rates for the 4 other dental anomalies in the PDC-DDP group (experimental group 2) vs the prevalence rates for these anomalies in the control group. All comparisons were performed with chi-square tests with the Yates correction (P <0.05), as were the comparisons between the sexes in experimental groups 1 and 2. The values for theta and gamma angles in experimental group 1 were compared with the values for these angles in experimental group 2, as well as with those in the control group. These statistical comparisons were made with analysis of variance (ANOVA) with the Bonferroni post-hoc test (P <0.05). RESULTS: The prevalence rate for PDC in experimental group 1 (28%) was significantly greater than in the control group (4.2%) (P <0.01). Significantly greater prevalence rates for aplasia of the second premolars, aplasia of the maxillary lateral incisors, and small maxillary lateral incisors were found in the PDC-DDP group (experimental group 2) compared with the control group. Significant sex differences (P <0.01) were found in both experimental groups. CONCLUSIONS: A significant relationship between distal displacement of unerupted mandibular second premolars and PDC was found. Because DDP is diagnosed earlier than PDC, it can be a developmental risk indicator for displaced maxillary permanent canines.

Influence of nutritional state on radiographic variables in upper canine teeth.

Permanent upper canine tooth impaction is related to both genetic causes and nutritional and local causes. Based on radiographic studies of children, Haavikko, 1974, calculated the median of the degree of calcification for each tooth according to age. The aim of our study was to establish associations between certain radiographic variables with respect to upper canine tooth buds and nutritional state in a population of schoolchildren. Thirty-three children of chronological ages 3 to 9 years from a population of rural schoolchildren took part in the study. The children were classified into three groups: malnourished, control and overweight. For the radiographic study we used a systematized technique using DSJ 70 kV radiographic equipment with 8 mA and Insight intraoral film (E F speed; Eastman Kodak, Rochester, NY). The images obtained from the 66 radiographic studies were scanned. The program Image tool for Windows was used to measure: (a) distance from the canine cusp to the intermaxillary suture, (b) outer angle formed between the aris of the canine tooth and the plane that cuts the intermaxillary suture perpendicularly, (c) degree of calcification (d) presence of supernumerary teeth. The values of these variables were analyzed statistically with the Kruskal-Wallis test of the SPSS program. The results were: (a) For the distance variable there is no significant difference between the malnourished and control groups (p > 0.05), although there are differences (p < 0.001) between the control and overweight groups; (b) There is no significant difference between nutritional states for the angle variable; (c) For the ratio between chronological age and dental age calculated according to degree of calcification, significant differences were found between the malnourished and overweight groups (p < 0.01), while the control group showed no difference regarding Haavikko's values (p > 0.05). Both the distance of the canine tooth bud and its degree of calcification vary in patients with nutritional disorders, therefore it would be useful to conduct a radiographic study at school age to detect tooth anomalies and reduce their consequences.

Bioengineered Tooth Buds Exhibit Features of Natural Tooth Buds.

Tooth loss is a significant health issue currently affecting millions of people worldwide. Artificial dental implants, the current gold standard tooth replacement therapy, do not exhibit many properties of natural teeth and can be associated with complications leading to implant failure. Here we propose bioengineered tooth buds as a superior alternative tooth replacement therapy. We describe improved methods to create highly cellularized bioengineered tooth bud constructs that formed hallmark features that resemble natural tooth buds such as the dental epithelial stem cell niche, enamel knot signaling centers, transient amplifying cells, and mineralized dental tissue formation. These constructs were composed of postnatal dental cells encapsulated within a hydrogel material that were implanted subcutaneously into immunocompromised rats. To our knowledge, this is the first report describing the use of postnatal dental cells to create bioengineered tooth buds that exhibit evidence of these features of natural tooth development. We propose future bioengineered tooth buds as a promising, clinically relevant tooth replacement therapy.

The characteristics of adjacent anatomy of mandibular third molar germs: a CBCT study to assess the risk of extraction.

This study aims to investigate the characteristics of adjacent anatomy of mandibular third molar germs (MTMGs). Three hundred Chinese patients aged 12 to 17 years old who received cone-beam computed tomography (CBCT) were enrolled. The continuity of cortical outline of inferior alveolar canals (IACs) in the region of MTMGs, the integrity of lingual bone cortex and the relationship between hard tissue part of MTMGs and IACs were investigated by observing CBCT data via the NNT viewer software. The age, degree of dental development, gender and location were recorded as variables. The associations between different variables and the observed data were analysed. The possibilities of disrupted cortical outline of IACs or the hard tissue part of MTMGs contacting IACs were significantly lower in 12 or 13 age groups, lower in Nolla stage ≤ 6. Males were significantly less than females in the incidence of disrupted cortical outline of IACs. As to the perforation of lingual bone cortex, no significant differences were observed in gender, ages, location or development stages. According to the CBCT images, anatomical factors contributed the lest to the risk of inferior alveolar nerve and lingual nerve injury in the 12 to 13 age group during removing the MTMG removal.