Maxillary First Permanent Molars Research Articles

Case report: Endodontic treatment of a permanent maxillary first molar with three roots and six root canals

Purpose: This study aimed to report the diagnosis and management of a permanent maxillary first molar (PMFM) with unusually complex root canal morphology.
 Case report: A 30-year-old male patient was referred to the endodontic department to continue endodontic treatment of the left PMFM. The referring dentist could not establish the patency of the canals in the mesiobuccal and distobuccal roots. Radiographically, the tooth had three almost straight roots associated with periapical radiolucencies, indicating periapical periodontitis. The examination of the pulp chamber floor, using a dental operating microscope, revealed the presence of six root canal orifices, three in the mesiobuccal root, two in the distobuccal root, and one in the palatal root. No confluence of multiple canals was detected using the electronic apex locator and K-files. The canals were shaped and cleaned with reciprocating nickel-titanium instruments and obturated using gutta-percha cones and a bioceramic sealer. After 2 years, the patient was asymptomatic and the tooth was clinically and radiographically without pathological findings.
 Conclusions: Careful examination of the pulp chamber floor using magnification and illumination is important for successfully managing complex canal morphologies. During endodontic treatment, dentists must consider that the PMFM may have more than four root canals.

Prevalence of caries in first permanent molar among children in Saudi Arabia: a retrospective study.

This study investigated the prevalence of dental caries in first permanent molars among children aged 7-14 years in Saudi Arabia. This retrospective cross-sectional study included 6,089 panoramic radiographs of boys and girls aged 7-14 years who visited Riyadh Elm University Dental Hospital in Riyadh. All the panoramic radiographs were examined by five calibrated examiners for caries, filling, missing, and pulp therapy in the first permanent molars (FPMs). The Chi-square test was applied at a p<0.05. A total of 24,356 FPMs were evaluated from the panoramic radiograph, 69.5% of FPMs were sound, 22.5% were carious, and 7.3% were treated. The prevalence of decayed FPMs was 30.5%. A statistically significant difference in the status of FPM was observed across genders. Caries in the mandibular FPM was significantly higher than those in the maxillary FPM at p<0.05. The prevalence of caries in the FPM was relatively high, and females had more decay than males. Additionally, the mandibular FPMs showed higher levels of caries than the upper FPMs.

Investigating permanent first molars of a Turkish pediatric sample in the eastern mediterranean region: A radiagraphic study

The early loss of first permanent molars (FPMs) may cause various problems in the dentofacial region. In the present study, it was aimed to evaluate the conditions of FPMs of a Turkish pediatric sample living in the Eastern Mediterranean Region. Dental panoramic radiographs (DPR) with good diagnostic quality and demographic characteristics of patients aged 7-17 years were retrospectively reviewed. Accordingly, affected teeth were evaluated by caries, filling, root canal treatment, retained root, apical lesion, and extraction. FPMs were compared by mandible, maxilla, and right-left jaw positions. The study was carried out with a total of 929 children, 442 (47.60) females and 487 (52.40) males. The participants were between the ages of 7-17 (M=12.10 ± 2.92). Among 3,974 FPMs evaluated, 2,018 (50.79%) were determined to be healthy, while 1,956 (49.21%) were affected. DC1 and F1 were the most common conditions of all evaluated FPMs. Regarding mandibular and maxillary FPMs, 1.137 of the FPMs1+FPMs2 and 881 of the FPMs3+FPMs4 were discovered to be healthy, and the difference was statistically significant (p&lt;0.001). However, any significant differences were not found between right and left FPMs by treatment. While FPMs remained healthy significantly more in the age group of 7-9 years (Group-I), extraction, root canal treatment, and apical treatment were significantly higher in the age group of 16-17 years (Group-IV) (p&lt; 0.001). Ultimately, it was concluded that FPMs start to be affected from early ages and that incidences of root canal treatment, extraction, and apical lesions become more prevalent with advancing age. This situation emphasizes the importance of applying preventive therapies as soon as the eruption of these teeth in children and attempting to increase relevant awareness among families.

Clinical evaluation of giomer- and resin-based fissure sealants on permanent molars affected by molar-incisor hypomineralization: a randomized clinical trial

BackgroundMolar-incisor hypomineralization (MIH) is a common condition among children that significantly increases the risk of caries. The objective of this research was to evaluate the clinical success of giomer- and conventional resin-based sealants applied on first permanent molars (FPMs) affected by MIH.MethodsOne-hundred FPMs with MIH which were indicated for non-invasive fissure sealant were selected in 39 children, aged 6–12 years. Using a split mouth design, the FPMs were randomized into two groups; Group 1. Resin sealant (etch-and-rinse + Conceal F) and Group 2. Giomer sealant (self-etch primer + BeautiSealant). Clinical evaluation was performed using the modified United States Public Health Service (USPHS) criteria at 1, 3, 6 and 12 months. The Log-rank, Fisher’s exact test and Kaplan–Meier analysis were used for statistical analysis.ResultsAt 12 months, the retention rates in Group 1 and Group 2 were 68% and %8, respectively (p = 0.000). The cumulative survival rates of conventional resin sealants were significantly higher than giomer sealants for all follow-up visits (p < 0.05). In Groups 1 and 2, the distribution of unsuccessful sealants on mandibular vs maxillary FPMs were 32.1% vs 31.8% (p = 0.612) and 91.7% vs 92.3% (p = 0.664), respectively. Although the success rate was higher for teeth with white opacities or lesions with less extension in Group 1, no significant difference was found. The average survival time was found as 10.46 ± 3.21 months in Group 1 and 4.02 ± 4.43 months in Group 2.ConclusionsThe conventional resin-based sealants yielded a better clinical performance over the 12-month evaluation period than the giomer sealants which were applied with self-etch primer. The high failure rate observed in giomer sealants could be explained by the possible deficiency in the etching capacity of self-etch primer on MIH-affected teeth.Trial registration ClinicalTrials.gov, NCT04929782. Registered 10 June 2021—Retrospectively registered, https://clinicaltrials.gov/ct2/show/NCT04929782.

The impact of caries status on supragingival plaque and salivary microbiome in children with mixed dentition: a cross-sectional survey

BackgroundSupragingival plaque and saliva are commonly used for microbiome analysis. Many epidemiological studies have identified deciduous teeth caries as a risk factor for caries development in first permanent molar (FPM); nevertheless, to the best of our knowledge, there are no reports on the effects of deciduous teeth caries on the microbiome of healthy FPM. Additionally, it remains unclear whether saliva can be used instead of supragingival plaque for caries microbial studies. Therefore, we aimed to elucidate this issue, and to characterize and compare the oral microbiome of healthy FPMs in children with different caries statuses and that from children with and without caries in a similar microhabitat, by PacBio sequencing. Currently, few studies have investigated the oral microbiome of children using this technique.MethodsThirty children (aged 7–9 years) with mixed dentition were enrolled; 15 had dental caries, and 15 did not. Supragingival plaques of deciduous molars and maxillary FPMs, and non-stimulating saliva samples were collected. DNA was extracted and the v1–v9 regions of 16S rRNA were amplified. Subsequently, PacBio sequencing and bioinformatic analyses were performed for microbiome identification.ResultsThe microbial alpha diversity of the saliva samples was lower than that of the supragingival plaque (p < 0.05); however, no differences were detected between deciduous teeth and FPMs (p > 0.05). In addition, the alpha and beta diversity of children with and without caries was also similar (p > 0.05). Nonmetric multidimensional scaling and Adonis analyses indicated that the microbial structure of salivary and supragingival plaque samples differ (p < 0.05). Further analysis of deciduous teeth plaque showed that Streptococcus mutans, Propionibacterium acidifaciens, and Veillonella dispar were more abundant in children with caries than in those without (p < 0.05); while in FPMs plaque, Selenomonas noxia was more abundant in healthy children (p < 0.05). No differences in microorganisms abundance were found in the saliva subgroups (p > 0.05).ConclusionWe have determined that supragingival plaque was the best candidate for studying carious microbiome. Furthermore, S. mutans, V. dispar, and P. acidifaciens were highly associated with deciduous teeth caries. S. noxia may be associated with the abiding health of FPM; however, this requires additional studies.

An In-Vivo cone-beam computed tomography analysis of root and canal morphology of maxillary first permanent molars in an Indian population.

The root and canal morphology of maxillary first permanent molars (MFPMs) is a very widely studied issue in endodontics. However, only one study has been conducted to date on this issue using cone-beam computed tomography (CBCT) in India, and the sample consisted of extracted teeth. To investigate the root and canal morphology of MFPMs in an Indian population, by using CBCT. 487 bilateral MFPMs (974 teeth) were assessed and the root and canal morphology were determined according to Vertucci's classification. In addition, the prevalence of a second mesiobuccal canal in the mesiobuccal root (MB2) was correlated with gender, age and arch side. Three roots were most commonly found in the MFPMs regardless of gender (P > 0.05), but this prevalence varied according to the side of the dental arch (P < 0.05). MB2 was present in 77.5% of 3-rooted teeth. Patients above 60 years had a higher incidence of these canals (84.7%) (P < .05). The occurrence of bilateral MB2 was 71.8% in 3-rooted MFPMs. Gender had no significant impact on the occurrence of bilateral MB2 in 3-rooted MFPMs (P > .05). The most common canal configuration was type IV (46.5%) and I (98.9%) in the mesiobuccal and distobuccal roots, respectively (P < .05). The prevalence of MB2 in 3-rooted MFPMs was higher in patients above 60 years of age. The root and canal morphology of MFPMs in an Indian population may have significant variations depending on the dental arch side and patient age.

Prevalence of Dental Caries and Fissure Sealants in the First Permanent Molars among Male Children in Riyadh, Kingdom of Saudi Arabia.

AimsTo evaluate the prevalence of dental caries and the presence of fissure sealants on the first permanent molars (FPMs) among 6 to 9 years old primary school boys in Riyadh, Kingdom of Saudi Arabia.Materials and methodsThe carious status and the presence of fissure sealants on the FPMs were examined in 1844 schoolboys, aged 6-9 years (the first three grades), from 17 randomly selected primary schools in Riyadh city, Kingdom of Saudi Arabia.Chi-square test was used to assess the significance of differences in prevalence and proportions.ResultsA total of 5394 FPMs were assessed in the 1844 children. Eighty-three point five percent of children were caries free. Only 0.8% of the children had at least one fissure sealant applied. At tooth level, the decayed FPMs counted for 10.6%. There was obvious underuse of fissure sealants on the FPMs; 0.5% (n = 25). The caries prevalence in the mandibular FPMs (14.4%), was significantly higher than in the maxillary FPMs, 7.7% (p < 0.01). The proportion of carious FPMs increased with age of the children significantly (p < 0.01). There was no significant difference in the proportion of the presence of fissure sealants among the three different grade/age groups (p > 0.05).ConclusionCaries prevalence in the FPMs was moderate but serious amongst this cohort of young students. This was opposed with very low use of fissure sealants.Clinical significanceCareful examination of the first permanent molars among children is mandatory because of their high caries susceptibility. It is important to increase public and dental professionals’ awareness of the effectiveness of fissure sealants and encouraging more placement.How to cite this article: Aldossary MS, Alamri AA, Alshiha SA, Hattan MA, Alfraih YK, Alwayli HM. Prevalence of Dental Caries and Fissure Sealants in the First Permanent Molars among Male Children in Riyadh, Kingdom Saudi Arabia. Int J Clin Pediatr Dent., 2018;11(5):365-370.

A survey of fissure sealants and dental caries prevalence in the first permanent molars among primary school girls in Riyadh, Saudi Arabia.

Objectives:To investigate the prevalence of caries and fissure sealants on the first permanent molars (FPMs) among 6–9-year-old girls in Riyadh, Saudi Arabia.Materials and Methods:The FPMs of 17,891 school girls from 120 randomly selected public primary schools were evaluated by visual and tactile examination for the carious status and the presence of fissure sealants. Chi-square test was used to analyze the data at level of 5%. Results:A total of 58,140 FPMs were assessed in the 17,891 children. Nearly 64.6% of the children were caries free. Only 1.3% of the children had at least one fissure sealant applied. At tooth level, the decayed FPMs counted for 24.6%. There was obvious underutilization of fissure sealants on the FPMs; 0.8% (n = 478). The caries prevalence in the mandibular FPMs (33%) was significantly higher than in the maxillary FPMs, 18.2% (P < 0.01). The proportion of carious FPMs increased with age of the children significantly (P < 0.01). There was no significant difference in the proportion of the presence of fissure sealants among the three different grade/age groups (P > 0.05).Conclusions:Caries prevalence in the FPMs was high and serious among this cohort of young students. This was contrasting the very low prevalence of fissure sealants.

Geometric features of second mesiobuccal canal in permanent maxillary first molars: a cone-beam computed tomography study

Background/purposeInadequacy to locate the second mesiobuccal canal (MB2) canal leads to the highest probability of endodontic failure in permanent maxillary first molars (PMFMs) and still remains a constant challenge for many clinicians. The aim of this study was to characterize the geometrical features between MB2 and other orifices of examined PMFMs using cone-beam computed tomography images. Materials and methodsA total of 108 teeth qualified in the cone-beam computed tomography image archives were enrolled in the present study. The intersecting point (T) was determined as the perpendicular line (h, altitude of triangle) projected from the vertex of the MB2 canal orifice to mesiobuccal canal orifice-palatal canal orifice line (MB1-P). We measured the geometric features of PMFMs with the MB2 canal, including the interorifice distances, area, altitude, and the ratio between the canal orifices. ResultsThe average interorifice distance was found to be 1.91±0.59 mm for MB1-MB2, 5.73±0.66 mm for MB1-P, and 4.11±0.79 mm for MB2-P, with significant gender difference for MB1-MB2 distance. For the MB1-T distance, a significant difference was found between genders (P=0.02), with males averaging 1.78±0.07 mm, and females 1.48±0.11 mm. For the MB1-P distance, the majorities of both genders were found in the 20–40% cut-off. A portion of the males exhibited a tendency towards the 40–80% cut-off, while females shifted in the reverse direction towards the 0–20% cut-off. ConclusionIn clinical scenarios, these anatomical characteristics of the root canals system could be beneficial to locating the MB2 canal.

Nonsyndromic form of oligodontia in a Chinese male patient: A rare case report

Oligodontia is one of the developmental disturbances seen in human with more than six congenitally missing teeth. Two forms of oligodontia which exist are the syndromic form and the nonsyndromic form. Mutation or deletion of MSX and PAX genes are implicated in oligodontia. Missing teeth often compromises patient's esthetics, function, and causes mental stress. Here, we highlight a rare case report of a nonsyndromic form of oligodontia with concomitant dental anomalies like taurodontism in maxillary permanent first molar and congenitally missing canine in a 17-year-old apparently normal Chinese male patient.

Canines are affected in 16-year-olds with molar-incisor hypomineralisation (MIH): an epidemiological study based on the Tromsø study: "Fit Futures".

This was to determine the prevalence, distribution of affected teeth and severity of MIH in adolescents from Northern Norway. It was part of a cross-sectional health survey Fit Futures including 16-year-olds from two neighbouring municipalities, Tromsø and Balsfjord. The prevalence of MIH was 13.9% (110 of 794). The maxillary first permanent molars (FPMs) were 1.6 times more frequently affected than in the mandible (P < 0.001). The FPMs on the right side were 1.2 times more often affected than the FPMs on the left side (P = 0.038). The maxillary incisors were 2.5 times more often affected than the incisors in the mandible (P < 0.001). The proportions of participants whose canines and incisors were involved were 22.8 and 41.8%, respectively. Altogether 201 FPMs were affected; 54.0% of these had opacities only, 24.3% had posteruptive breakdown (PEB), 18.8% had atypical restorations, and 3.0% had been extracted due to MIH. The buccal surfaces were most often affected in FPMs. More severe lesions were found in the mandibular FPMs compared with the maxillary FPMs (P = 0.002). In the lower canines, only opacities were recorded, while in the upper jaw 13.0% of the affected canines showed PEBs. The distribution of MIH in the dentition was not symmetrical. The prevalence of MIH (13.9%) in the study population of 16-year-olds from Northern Norway is consistent with previous Scandinavian reports. The distribution pattern shows that one participant in four with MIH had at least one affected canine. Further studies are needed to describe the localisation of defects on the enamel surface and to relate these findings to enamel thickness and the duration of amelogenesis.

Nueva forma anatómica de cara oclusal en primeros molares superiores permanentes

Introducción: un surco no tipificado, en los primeros molares superiores permanentes (PMSP), permitió distinguir dos tipos de cara oclusal: la descrita por Figún y Garino, Tipo I para el grupo de investigación, y Tipo II, caracterizada por la presencia de un surco sobre la apófisis oblicua, que la discurre sin interrumpirla. Este elemento dio lugar a la realización de estudios con el fin de deter- minar su presencia e investigar origen, dirección y longitud para caracterizarlo y registrarlo como una nueva forma anatómica de cara oclusal. Métodos: se trabajó con PMSP naturales inertes y de pacientes para evidenciar la presencia del surco y con PMSP que presenten el surco para caracterizarlo. El método fue observacional y descriptivo. Resultados: existe un predominio de casos en los que la cara oclusal del PMSP presenta un surco que, sin cortar a la apófisis oblicua, la recorre parcialmente. Se origina en la fosa principal central triangular. La dirección es hacia distal y palatino y su longitud varía entre 1 y 2 mm. Esto ha permitido registrar esta cara oclusal, como PMSP Tipo II. Conclusión: el PMSP presenta dos tipos de cara oclusal: Tipo I y Tipo II.DOI: http://dx.doi.org/10.16925/od.v10i18.717

Clinical effects of modified Nance arch appliance in the treatment of ectopic eruption of maxillary first permanent molar

To evaluate the effect of modified Nance arch appliance in the treatment of ectopic eruption of maxillary first permanent molar. Thirty children with unilateral ectopic eruption of maxillary first permanent molar were treated with modified Nance arch appliance. The mesial angle of the maxillary first permanent molars and the magnitude of the primary second molar distal root lesion before and after treatment were measured on the panoramic radiographs and analyzed statistically. All 30 children completed the treatment. The mesial angle of the ectopic side significantly changed from (75.2 ± 7.6) ° before the treatment to (92.9 ± 5.2) ° after the treatment (t = -11.082, P < 0.05). The root lesion of the ectopic side significantly enlarged after the treatment, but there was no significant change on the normal side. The treatment of ectopic eruption of the maxillary first permanent molar using modified Nance arch appliance was successful. The attention should be paid to the magnitude of the primary second molar distal root lesion before and after treatment and it is suggested to start the treatment when mild root resorption appears.

Clinical analysis of the treatment of the second mesiobuccal canal of maxillary first permanent molars

Objective To analyze the treatment of the second mesiobuccal canal of maxillary first permanent molars.Methods 86 patients received maxillary first permanent molar treatment were colleted,all these patients took X-ray dental films before the treatment.Oblique quadrilateral were chosen in this group.All root canal of molars were explored by probe with eyes or under the root canal microscope.The root canal was prepared according to the stepback technique.Every root canal was treated with gutta-percha.Results 58-MB2 were found in all these 86-cases maxillary first permanent molar.55-MB2 located the mesial side of the line connected the mesiobuccal root and the palatal root.30d after the root canal therapy,the effective rate in the group with MB2 was 93.10％,while the effectiverate in the group without MB2 was 100.00％.There was significant difference between the two groups(x2 =48.377,11.924,all P ＜ 0.05).Conclusion The incidence of MB2 of maxillary first permanent molar is very high.During treatment,oblique quadrilateral should be chosen combined with the root canal microscope.This method could improve the detection rate.EDTA could reduce the difficulty of root canal preparation. Key words: Molar; Root canal therapy

The effects of unilateral premature loss of maxillary primary molars on the dental arch dimensions

Background: The aim of the study was to evaluate the amount of changes in the horizontal and vertical maxillary arch dimensions measurements following the premature loss of primary molars. Materials and methods: The sample consist of (50) children with unilateral prematurely extracted either first or second primary molars at the mixed dentition stage. Results and Conclusions: Results shows that there was an increase in the vertical incisor to canine distance (A) with both premature loss of first & second primary molars due to distal movement of primary canines and at the same time there were a significant loss of space in the extraction space with premature loss of second primary molar due to a mesial movement of maxillary first permanent molars which at the same time tip lingually and this is clear obvious from the decrease in the inter-molars distances horizontally.

Treatment of ectopic eruption of maxillary permanent fi rst molars with modifi ed halterman appliance

Treatment of ectopic eruption of maxillary permanent fi rst molars with modifi ed halterman appliance

Ectopic eruption of the maxillary first permanent molar: characteristics and occurrence in growing children.

The purpose of this study was to determine the characteristics and occurrence of the ectopic eruption of the maxillary first permanent molar in a sample of growing Spanish children. A descriptive, observational, retrospective study was done using the radiographs of 509 consecutive patients, who were in the first phase of mixed dentition. A method was designed to evaluate the amount of pathologic resorption of the second maxillary primary molar and the impaction of the first permanent molar measured in millimeters. Statistical analysis of the studied variables was done using chi-square, analysis of variance, and Pearson correlation coefficient. The frequency of occurrence was 4.3% with no differences in both sexes. Of these, 36.4% were unilateral and 63.6% bilateral with a right:left relation of 3:1. Of the 36 ectopic molars, 69.4% self-corrected spontaneously. In such cases, the pathological resorption of the root of the second maxillary primary molar and its adverse clinical implications were persistent. The relation between self-correction and impaction was 2.27:1. The average impaction on the right side was 2.91 mm and 1.6 mm on the left side. Correlation between the magnitude of resorption and grade of impaction was not observed. Although resorption was found on grades I and II, spontaneous self-correction could occur without arch length loss. However, on grade III or more, therapeutic intervention has to be done. The benefit of early diagnosis and treatment of the maxillary first permanent molar is the prevention of the premature loss of second maxillary deciduous molar and the resulting malocclusion.

Statistical evaluation of possible factors affecting the sagittal position of the first permanent molar in the maxilla.

A cephalometric analysis was designed to evaluate several factors that may affect the sagittal position of the maxillary first permanent molar. A total of 184 Class II and Class I malocclusion patients were randomly selected before orthodontic treatment. The mandibular and palatal planes were related to Frankfort Horizontal and used to create the interjaw or B angle. Age and cephalometric landmarks (Ba, N, point A, pterygomaxillary fissure, and maxillary molars) were projected at right angles to the Frankfort Horizontal for effective length. Actual maxillary length and actual molar location were determined by projecting landmarks at right angles to the palatal plane. Correlation coefficients and P values were used to evaluate the data with a minimal significance value of .05 to determine a 95% confidence level. A statistically significant linear and proportional positive correlation (P < .0001) existed between molar location, age, and maxillary size. There was a strong negative correlation (P < .0001), both linearly and as a proportion of the actual length of the maxilla, between the actual position of the maxillary molar and the interjaw and mandibular plane angles. A significant correlation also existed between the molar position and palatal plane angles. The results show that increased interjaw, mandibular, and palatal plane angles are accompanied by a more posterior position of the maxillary first molar in the maxilla, whereas the molar occupied a continuing more forward position in the maxilla with increasing age, cranial base length, and maxillary size.

New regression equations for predicting the size of unerupted canines and premolars in a contemporary population.

The determination of a tooth-size to arch-length discrepancy in the mixed dentition requires an accurate prediction of the mesiodistal widths of the unerupted permanent teeth. This is an essential factor in treatment planning. The aim of this study was to validate Tanaka and Johnston's analysis on 600 Syrian patients aged 14-22 years. Tanaka and Johnston's tables, equations, and approximations were modified in order to improve the accuracy of the prediction. The correlation coefficients found between the size of the permanent mandibular central incisors and maxillary first molars (31, 41, 16, and 26) and the maxillary and mandibular canines and premolars were high (r = .72 and .74, respectively). New, more accurate prediction tables applicable at earlier ages, and new regression equations were constructed. In addition, new easier approximations were developed to allow the prediction of the size of the unerupted maxillary canines and premolars by adding 6 mm to the half-widths of teeth 31, 41, 16, and 26. The analogous prediction of the size of the unerupted mandibular canines and premolars was obtained by adding 5.5 mm to the half-widths of same teeth, 31, 41, 16, and 26.

Dental arch asymmetry in children with large overjets.

Little is known about asymmetry of children's dental arches. The purposes of this study were to quantify and describe dental arch asymmetry of 151 children with large overjets, and to determine if a spatial relationship exists between dental landmarks in opposing arches. The median palatal plane (MPP) was the reference for transverse measurements. A computer-constructed transverse palatal plane (TPP) was the reference for anteroposterior measurements. More than 30% of the children had transverse asymmetries > or = 2 mm at the maxillary first permanent molar (paired t-test; p = 0.0001). The highest mean transverse asymmetry (1.59 +/- 1.24 mm) and anteroposterior asymmetry (1.51 +/- 1.23 mm) were at the maxillary first permanent molars. A higher proportion of children with large overjets had clinically significant intra-arch asymmetries (> or = 2 mm) at several bilateral landmarks than norms (99% confidence intervals). Only 3% of these children exhibited interarch molar asymmetries > or = 4 mm. The position of the landmarks in one arch varied with the landmarks in the opposing arch (Pearson's correlation; p = 0.0001). Although many children with large overjets have significant intra-arch asymmetries, few exhibit asymmetric interarch asymmetries.