Effects of ethnicity and birth month on localized enamel hypoplasia of the primary canine

Localized enamel hypoplasia of the primary canine (LHPC) is produced by a different mechanism from that causing linear enamel hypoplasia, and yet contributes disproportionately to epidemiological studies of enamel hypoplasia in childhood that do not separate the two etiological types. LHPC results from impact, probably self-inflicted by infants mouthing objects, to the unerupted primary canine crown through abnormally fenestrated cortical bone overlying the crypt. Examination of the primary teeth of ninety-six children whose mothers were enrolled in the Healthiest Babies Possible Program in Vancouver showed an average prevalence of 31 percent with LHPC (ranging from 19 percent in Vietnamese Canadians to 56 percent among Indocanadians). This is much higher than previously reported for unselected samples from Vancouver, but equivalent to studies in the USA. Mean hours of sunshine in the birth month of children with LHPC is 141.7 hours and those without is 169.4 hours; the difference is statistically significant (p = .0383). Seasonal increase in food costs and reduced availability of fresh foods containing vitamin A are thought to contribute to facial osteopenia predisposing the infant to LHPC.

Conservative multidisciplinary treatment approach in an unusual odontodysplasia

An unusual case of odontodysplasia is presented, involving both primary and permanent dentition, with oligodontia of permanent teeth and hypoplasia, taurodontism and incomplete eruption of a first permanent molar. In order to improve the patient's appearance, occlusion and function, his intra- and inter-arch relationships were altered. To accomplish this, a multidisciplinary treatment approach was adopted, involving restorative and prosthetic treatments by a pediatric dentist, accompanied by periodontal surgery, endodontics and orthodontics.

Children with hypoplastic enamel defects of primary incisors are not at increased risk of learning-problem syndromes

Developmental enamel defects of primary teeth have been associated in earlier reports with motor, hearing and psychological disturbances. The relationship between hypoplastic enamel defects and learning problems had not been evaluated previously. For a total of 149 girls and 196 boys we collected a primary tooth shortly after shedding and approximately 2 years later a teacher-completed questionnaire about function in school. Children with a hypoplastic enamel defect of one of their primary incisors were no more likely than their peers without an enamel defect to have any of 7 different learning problem syndromes. In the absence of reason to suspect selection bias, confounding, or misclassification of hypoplastic defects or school problems, we conclude that hypoplastic enamel defects are not associated with teacher-identified learning problems.

Dental and craniofacial findings in a child affected by glycogen storage disease type III

This paper reports on previously undescribed dentofacial features a child suffering from Glycogen-Storage Disease type III with hepatomegaly and hypertransaminasemia with muscular involvement. Deficient craniofacial development, reduced width of the upper jaw resulting in posterior cross-bite, and taurodontism of the primary dentition were found. Pathogenetic basis for craniofacial abnormalities is discussed. Cooperation between pediatricians and pediatric dentists is strongly recommended for an early diagnosis and treatment of the dentofacial defects of the syndrome.

Split hand/split foot deformity and LADD syndrome in a family: overlap between the EEC and LADD syndromes

A mother and daughter are reported with apparently dissimilar syndromes. The mother has a split hand/split foot deformity and the daughter a condition consistent with a diagnosis of LADD syndrome. Absence of clefting and deficient formation of saliva and tears are the main signs that differentiate the LADD from the EEC syndrome. However, no distinct feature is constant between these two autosomal dominant disorders that show great phenotypic variability. This report emphasises the overlap between the LADD and the EEC syndromes.

Congenitally missing permanent mandibular incisors and their association with missing primary teeth in the southern Chinese (Hong Kong)

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.

The absence of correlations between a clinical classification and ultrastructural findings in amelogenesis imperfecta

This study was performed to examine whether a clinical classification of different phenotypes of amelogenesis imperfecta could be discernible at the ultrastructural level. Seventeen primary teeth from 16 children with hypomineralization, hypomaturation, or hypoplastic variants of the disease were collected for histologic studies of the enamel by means of polarized light microscopy, scanning electron microscopy (SEM), and secondary ion mass spectrometry (SIMS). Polarization microscopy showed that the enamel was hypomineralized; in six teeth a wavy configuration of the enamel prisms also appeared. Three histomorphologic main types could be discerned. In 10 of the teeth extensive hypomineralization of the bulk of the enamel was found. One tooth had an unusually thick enamel with only a thin normally mineralized surface layer. SIMS images showed less pronounced signals from Ca2+ and Na+ but with stronger signals from Cl- and CN-, representing the organic component of enamel. The SEM images showed an irregular prism pattern with marked interprismatic areas. Irrespective of the clinical appearance or the hereditary pattern the main findings were hypomineralized enamel with or without wavy bands. Neither of the analytical methods used in this paper distinguishes between the clinical phenotypes of amelogenesis imperfecta.

Enamel pearls in the primary dentition: report of two cases

Two cases of enamel pearls present in the furcation area of primary mandibular second molars are reported. Clinical and histologic examination revealed that the pearls were composite enamel pearls. Complications arising from this uncommon entity may include delayed exfoliation of the primary tooth and/or deviation of the succedaneous tooth. Radiographic interpretation and detection of the enamel pearl may be complicated by the superimposition of the developing permanent tooth, and their incidence may be higher than reported.

Prevalence of dental caries and enamel defects in the primary dentition of Antiguan pre-school children aged 3-4 years including an assessment of their habits

In 1989 a national survey was carried out on children aged 3 to 4 years attending nursery schools, to investigate the prevalence of caries experience, nursing bottle caries and enamel defects in the primary dentition, and these children's dentally related habits. In the first part of the study, examination of 482 Antiguan children showed that the dmft and dmfs values were 0.80 and 1.26 respectively, and that 77 per cent of the children were caries free; 4.6 per cent of children had nursing bottle caries; and enamel defects occurred in 24 per cent of children. No significant difference was found in oral health between urban and rural samples. In the second part, which was an interview survey, habits such as thumb sucking (13 per cent), not brushing their teeth (3 per cent), and swallowing fluoride toothpaste (13 per cent) were found among 369 children. In the third (a questionnaire) survey, a response rate of 63 per cent was obtained. Significantly more of the children with nursing bottle caries (78.6 per cent) had the habit of sleeping with a feeding bottle than occurred in caries free children (25.6 per cent), but there was no difference in the infant feeding pattern. The children with enamel defects were breast fed for a shorter period and had an earlier introduction to bottle feeding, compared with children without enamel defects. In the final part of the survey, an assessment of snack eating habits at school, a 58 per cent response rate was achieved. The majority of children often brought healthier snacks, together with daily sugar-rich drinks. Significantly more caries free children brought sugary snacks less frequently than children with caries experience.

[Secondary retention of permanent molars. I. Clinical, radiologic and histologic characterization]

The clinical, radiographical and histological aspects of secondary retention in permanent molars were studied in a group of 53 patients with 81 secondarily retained permanent molars. First molars turned out to be affected most frequently. The mean infraocclusion at the patients' first visit was 4.3 mm. After six months, infraocclusion had increased in adolescents. It seemed to be stable in adults. Tilting of adjacent teeth was observed in 39 cases of secondary retention. A solid, clear percussion sound and a partial absence of the periodontal ligament space on radiographs was only noted in less than 20% of the affected molars, while histological examination of 38 removed molars revealed that local areas of ankylosis were present in all cases. During a follow-up period of four years, six new cases of secondary retention were observed in the same population.

Fusion of primary mandibular teeth: report of case

The treatment and observation of a child with fused mandibular primary lateral incisor and canine are presented. Asymmetries such as those caused by fusions can lead to serious malocclusion.

Maxillary lateral incisor of subjects with cleft lip and/or palate: Part 1

As a pilot study, dental casts of 30 patients with unilateral cleft lip and palate were selected and examined from the longitudinal data in the Department of Orthodontics, Kyushu University Dental Hospital. Dental casts of the anterior teeth were sectioned at right angles to the long axis of the tooth 2 to 3 mm below the incisal edge. The teeth were differentiated according to their cross sections. They were classed as lateral incisors or other types by the ratio of labiolingual diameter to mesiodistal diameter and the flatness labiolingually. Dental casts of 309 additional patients with cleft alveolus were examined subjectively based on above findings. In primary dentition, 183 of 184 teeth on the cleft side were incisal type. One tooth was canine type. In permanent dentition, 42 of 78 teeth on the cleft side were conical type, 20 teeth were intermediate type, and 16 teeth were incisal type. As a conclusion, the tooth on the cleft side is almost certain to be a lateral incisor, not a supernumerary canine tooth. As well, their form was normal in the majority of the primary dentition, but malformed in the permanent one.

Maxillary lateral incisors of subjects with cleft lip and/or palate: Part 2

Maxillary lateral incisors on the alveolar cleft were investigated in 431 cleft children registered in the Department of Orthodontics, Kyushu University Dental Hospital. The majority of primary maxillary lateral incisors were located on the distal side of the alveolar cleft in both unilateral cleft lip and alveolus (UCLA) and unilateral cleft lip and palate (UCLP) subjects. Permanent teeth in UCLA tend to be located distally, but in UCLP they tend to be congenitally absent (p less than .01). The majority of primary teeth had normal shapes; the majority of permanent teeth were of intermediate type or were missing congenitally. One third of the UCLA and one half of the UCLP subjects who had primary maxillary lateral incisors were not followed by permanent replacements. The location of the majority of permanent maxillary lateral incisors tallied with that of the primary ones except in four UCLA, ten UCLP, and two bilateral cleft lip and palate (BCLP) subjects. Four UCLA and ten UCLP subjects who had primary lateral incisors on the distal side were followed by their permanent successors on the mesial side. Three UCLP and one BCLP subjects had permanent maxillary lateral incisors even though they had no temporary predecessors.

Antecedents and correlates of hypoplastic enamel defects of primary incisors

Four hundred and fifty-five exfoliated primary incisors were obtained from children whose mothers provided information about a wide range of pre-, peri-, and postnatal characteristics of both the mother and child. These teeth then were examined for the presence of hypoplastic enamel defects (HED). The basic form of the null hypothesis tested was that children who had HED of a primary incisor did not differ from those who did not have such a defect. Of the primary incisors examined, 18.5% had HED (25.0% maxillary and 10.1% mandibular). The following items were found to be associated most strongly (P less than 0.003) with an increase in a child's risk of developing HED; 1) maternal antenatal history of smoking, higher prepregnancy weight, and failure to obtain prenatal care during the first trimester; 2) prematurity, low birth-weight and their associated correlates; and 3) postnatal measles infection. Left-handedness, maternal tea and Tylenol (McNeil Consumer Products Co., Fort Washington, PA) consumption, and failure to screen for undue lead burden were associated less prominently (P less than 0.05) with HED prevalence. Season of birth and serum and dentin lead levels were not related to the prevalence of HED. Many of these risk factors are also covariates of low socioeconomic status such as suboptimal nutrition and increased risk of infection. Additional investigation is needed to delineate the associations between specific pre- and perinatal nutritional and infectious factors, socioeconomic status, and HED development.

Mesiodens in the primary dentition stage: a radiographic study

Five hundred and forty-three Chinese patients in the primary dentition stage were evaluated for mesiodens with maxillary, anterior occlusal films. Compared with other studies, a higher prevalence was found, using different age-groups and diagnostic methods. The distributions of mesiodens by sex, location, and direction were also studied. Because mesiodens could interfere with normal development of the occlusion, especially in the early mixed dentition stage, early diagnosis, using appropriate radiographs during the primary dentition stage, could lead to more comprehensive treatment planning.

Unusual dentinal changes in dentinogenesis imperfecta associated with osteogenesis imperfecta. A case report

A case is described of a boy with dentinogenesis imperfecta associated with osteogenesis imperfecta. The dentin of extracted deciduous teeth was found to show an abrupt transition to a normal tubular structure before a reversion to the more typical structure seen in dentinogenesis imperfecta. This change in the dentin appeared to have occurred in a chronologic manner. The possibilities that either a metabolic disturbance or a temporary reduced expression of the mutant gene had caused the abnormality and could account for the unusual histologic findings are discussed.

An unusual giant cell lesion in a child with vitamin D-resistant rickets

This paper reports the presence of a focus of giant cells in a sinus tract associated with an abscessed primary tooth in a patient with vitamin D-resistant rickets. The relevance of this giant cell lesion to the systemic disorder is discussed.

Hypodontia of the primary and permanent dentition

The prevalence, possible etiological factors and management of hypodontia was briefly reviewed. A report of a case of hypodontia affecting the primary and permanent lower incisors was described.

Dilaceration of a primary tooth

A case is presented in which a non-vital maxillary primary incisor failed to resorb, its root apex appeared in the labial sulcus and further investigation showed it to be dilacerated.

A primary double molar tooth in a child with Russell-Silver syndrome

The prevalence of double teeth in the primary dentition, for the British schoolchild, is 1.6%. Although primary double teeth in the anterior region of the mouth are not uncommon, double teeth in the primary molar region are rare. This case report describes the intra-oral findings, and in particular a case of a primary molar double tooth, in a young child who has Russel-Silver syndrome.

Rieger's syndrome

Rieger's syndrome which is a congenital progressive, autosomally dominant, ophthalmic anomaly has certain associated somatic dentofacial and systemic features. These extra dentofacial and systemic findings can play very important role in diagnosing this syndrome so as to prevent the ocular complications. This article reports such a case in a 20-yr-old woman and discusses somatic features along with the clinical importance of early diagnosis.

Treatment of a pseudo-class III relationship in the primary dentition: a case history

In conclusion, posterior and anterior crossbites of the primary dentition should be corrected, once recognized, to allow for normal dental base development and subsequent favorable skeletal growth, provided the analysis of the case reveals no gross boney discrepancies. To quiet any archaic ideas of delaying posterior crossbite correction until the eruption of the permanent first molars, a pilot is being undertaken to determine whether there is a statistical difference in the need for retreatment of patients, when the permanent first molars erupt with the use of either the Porter, Quadhelix, or R.P.E.-type appliances. It is hoped that this will support the low retreatment frequency of 7.6 percent reported by Kutin and Hawes.

Enamel hypoplasia in the primary dentition: a review

Clinical significance of enamel hypoplasia includes poor esthetics, tooth sensitivity, malocclusion and predisposition to dental caries. It may provide diagnostic clues as to genetic influences and systemic diseases, as well as to any trauma during the span of dental development. These systemic factors include birth trauma, infections, nutritional disorders, metabolic diseases, and exposures to chemicals such as tetracycline, lead, and fluoride. Inherited types form a relatively small component overall, including genetic abnormalities of enamel formation, or dental features of many inherited diseases or dysmorphic syndromes. Developmental enamel defects range in prevalence from 4 percent to 60 percent, depending on the criteria and the population studied. It is likely that many of these individual factors may in fact act through a central mechanism: mineral deficiency.

Macroscopic enamel defects of primary anterior teeth--types, prevalence, and distribution

A total of 40.7% of 509 exfoliated primary anterior teeth from children who were healthy products of uneventful pregnancies exhibited at least one macroscopic enamel defect. Twenty percent of the teeth exhibited hypoplastic defects (HD), 12.4% exhibited white-cream opacities (WCO), and 9.8% exhibited yellow-brown opacities (YBO). Slightly more than a third (33.6%) of the teeth had defects we considered to be developmental enamel defects (DED). The occurrence of DED did not vary with gender, side of mouth, individual tooth types, or racial background. DED occurred with increased frequency on maxillary teeth, facial surfaces, and the middle third of affected surfaces. These locations have thicker enamel than other sites and may be more susceptible to insult if vulnerability is a function of metabolic demand of the rapidly secreting ameloblasts. Twenty-five per cent of the maxillary incisors and 10.1% of the mandibular incisors exhibited HD whose locations coincided with enamel forming at birth. A third (33.3%) of the canines exhibited HD, which occurred most commonly in the middle third of the facial surfaces. These defects are believed to occur approximately six months postnatally and may be primarily due to mechanical trauma. YBO most commonly occurred on the middle third of the facial surfaces, while WCO on the gingival third. Neither YBO nor WCO followed a chronologic pattern.

[The congenital absence of the permanent upper lateral incisors with the persistence of the deciduous canines in a subject of the Iron Age from the Sulmona (AQ) necropolis]

The paper reports a case of bilateral agenesia of the permanent upper lateral incisors associated with the persistence of the deciduous eye teeth placed between the first premolars and the permanent canine teeth which, in turn, had emerged in place of the agenetic lateral incisors (situs dentis inversus) in a adult male from the Iron Age whose skeletal remains were exhumed from tomb no. 58 of the Sulmona necropolis (AQ). The authors place the case in the context of agenesia as found both in today's population and in ancient times.

Incontinentia pigmenti (Bloch-Sulzberger syndrome). A case report

Incontinentia pigmenti is a rare genodermatosis with multiple manifestations affecting the skeletal, ocular, dental, and other tissues. More than 95% of reported cases occur in females, and more than 60% of reported cases involve some dental abnormality. A brief review of the literature and a case in a 7-year-old girl with the disease are presented.

Bilateral birooted maxillary primary canines: report of two cases

X-ray examination disclosed bifurcation of both maxillary canine teeth in two unrelated patients, both four-year-old children. All other dental findings were unremarkable and their medical histories were noncontributory. Bifurcation of primary canines is an extremely rare condition.

[Statistical studies on numerical anomalies of teeth in children using orthopantomograms. Hyperdontia]

Statistical studies on numerical anomalies of teeth using orthopanthomograms had been attempted. In this paper, hyperdontia had been researched using 4009 orthopanthomograms of pedodontic patients. The tested were following: Male: Age 2-5 1036, 6-11 905, 12-22 Total 1963 Female: Age 2-5 1032, 6-11 985, 12-29 Total 2046 respectively. And 119 hyperdontia cases (143 teeth -1 tooth: 95 cases, 2 teeth: 24 cases) were found. Male: 84 cases 104 teeth (1 tooth: 64 cases, 2 teeth: 20 cases) Female: 35 cases 39 teeth (1 tooth: 31 cases, 2 teeth: 4 cases). Form supplemental teeth (normal form) deciduous teeth 4 teeth (4 anteriors containing 2-3 C in a case.) permanent teeth 32 teeth (anteriors: 28, premolars: 4) supernumerary teeth (abnormal form) deciduous cuspid like, conical 97 teeth (upper incisors) queer form 10 teeth (upper anteriors) Eruption line normal 85 teeth inversive 46 teeth horizontal 12 teeth Depth in alveolus Hyperdontia are classified in following: 1. in the alveolus deeper than permanent dentition in deciduous teeth period type I 1.7% in permanent teeth period type I' 23.5% 2. in the same depth of permanent dentition in deciduous teeth period type II 24.4% in permanent teeth period type V 9.2% 3. in the depth between permanent dentition and deciduous dentition type III 38.7% 4. in the deciduous dentition type IV 3.4% Type I, Type I', and Type III (total 63.9%) possibly belong to different teeth generation from deciduous and permanent teeth.

Talon cusp in primary dentition--case report

A case of talon cusp in the primary maxillary left central incisor is reported. This dental anomaly was not associated with any other somatic or dental abnormality. Though pulpal extension into the cusp was detected radiographically, clinical examination after the cusp was ground failed to reveal any pulpal extension. The tooth was badly carious and was restored with a polycarbonate crown.

[Statistical studies on numerical anomalies of teeth in children using orthopantomograms--congenital hypodontia]

Statistical studies on numerical anomalies of teeth using orthopanthomograms had been attempted. In this paper, congenital hypodontia had been researched using 4009 orthopanthomograms of pedodontic patients. The tested were following; Male: Age 2-5 1036, 6-11 905, 12-22 Total 1963 Female: Age 2-5 1032, 6-11 985, 12-29 Total 2046 respectively. Many interesting results have been acquired, i.e. A. Congenital Hypodontia of Deciduous Teeth total 62 cases (78 teeth) 1 tooth defect--46 cases 2 teeth defect--16 cases B. Congenital Hypodontia of Permanent Teeth total 314 cases (566 teeth) 1 tooth defect--150 cases 2 teeth defect--115 cases 3 teeth defect--23 cases 4 teeth defect--18 cases 5 teeth defect--6 cases 6 teeth defect--0 case 7 teeth defect--1 case 8 teeth defect--1 case C. Defect Position deciduous teeth i2--83.3% permanent teeth P2--42.4% I2--36.4% D. Rare cases Symmetric defect (upper and lower): 2 cases, bisymmetric defect (right and left): 93 cases, symmetric and bisymmetric defect: 7 cases, defect of deciduous teeth and the succeeding permanent teeth: 37 cases, or in other expression, 2 B 1 case, 5/5 1 case, B 2 B B 1 case, 2 2 17 cases, 2 2 4 cases, 1 1 1 case, 3 3 1 case, 5 5 1 case, 3 2 2 3 1 case, 5 2 2 5 1 case, 5 4 4 5 1 case, 7 2 2 7 1 case, 7 3 3 7 1 case, 7 5 5 7 1 case, 7 5 2/2 2/2 5 7 1 case, 5/5 5/5 7 cases and 2B 2B 1 case, 3C 3C 1 case, B2 B2 8 cases, C3 C3 2 cases, 2B 5 cases, 2B 1 case, B2 10 cases, A1 1 case, A1 1 case, B2 6 cases' E5 1 case... In addition, the data have no significant difference in right and left, male and female. And for many reasons, we criticize the established theory (?) that congenital hypodontia is a systemic degeneration in human evolution. So we propose a following, simple and not incompatible concept--eventually congenital hypodontia except hereditary cases appear in many chances when development of dental germs (I2, P2, M3) is later than the surroundings and the space for it is remarkably deficient.

Dental anomalies in cleft lip and palate: an unusual case

A cleft palate case is reported in which there is an unusual pattern of hypodontia involving aplasia of the primary second molars, but development of the corresponding second premolars. This paper discusses some of the implications of this situation and stresses the need for very thorough clinical and radiographic examination.

Triplication and twinning in one dental arch: report of a case

This report documents the case of a young patient who presented with dental conjoining anomalies in both sides of the maxillary arch. One defect involved primary incisor twinning and the other a rare instance of primary incisor triplication--three conjoined teeth.

Dental findings in mucopolysaccharidosis type IV A (Morquio's disease type A)

Dental examinations on nine patients with mucopolysaccharidosis type IV A (MPS IV A, Morquio's disease type A) were carried out. Detailed medical, radiologic, and biochemical studies of each case were also performed independently. Dental changes were present in all cases, although the severity varied. The severity of the dental changes did not correlate with the clinical or biochemical findings in all cases. These dental changes are seen only in MPS IV A (N-acetylgalactosamine-6-sulphate sulphatase deficiency) and are not found in MPS IV B (beta-galactosidase deficiency) or the recently delineated MPS IV C (enzyme defect unknown). The dental changes can aid in the diagnosis of patients affected by MPS IV A and are especially useful in mild atypical cases.

Dental twinning anomalies: the nomenclature enigma

Dental twinning results from abnormal events in the embryologic development of teeth. This paper describes the impossibility of assigning precise diagnostic terms, such as germination, fusion, macrodontia, and concrescence, to dental twinning anomalies because the entire course of odontogenesis cannot be witnessed. Traditional nomenclature is reviewed and seven cases that exemplify the principle are presented. Modification of nomenclature to describe dental twinning defects is suggested.

Anomalous morphologic formation of deciduous and permanent teeth in a 5-year-old 15th century child: a variant of the Ekman-Westborg-Julin syndrome

A gross morphologic anomaly affecting both the primary and secondary teeth of unknown cause is presented. A 5-year-old American Indian child exhibited macrodontia, extreme shovel-shaping, agenesis, three-rooted deciduous molars, dens invaginatus, and other less striking dental features. This case represents the earliest example of a variant of the Ekman-Westborg-Julin syndrome reported in the New World.

[Ankylosis of deciduous teeth]

The authors reviewed the literature concerning ankylosis of deciduous teeth, with emphasis on the diagnosis, the incidence, the aetiology and the treatment of this manifestation, illustrated with representative clinical cases.

Single maxillary central incisor in association with mid-line anomalies

A single maxillary central incisor may occur as an isolated dental finding. However, it has also been reported to occur in association with autosomal dominant holoprosencephaly, in association with growth retardation with or without growth hormone deficiency and occasionally in association with other mid-line developmental defects. Holoprosencephaly and pituitary dysfunction are two specific examples of mid-line defects and this report emphasises that other mid-line defects may be associated with a single maxillary central incisor. We recommend that patients with this dental anomaly should be referred for a detailed medical examination.

Enamel defects in the primary dentition of children born weighing less than 2000 g

The findings for enamel defects in the primary dentition of a group of low birthweight (LBW) children were related to their perinatal medical histories. Examination of 110 LBW children and 93 control children aged 5 years showed that significantly more of the LBW children (71%) had hypoplasia than controls (15%), but there was no difference in opacities alone (LBW 25%, control 26%). In the LBW group, defects were seen more often in children classified as ill during the perinatal period, who received ventilator support or intravenous alimentation and in those children born at less than 32 weeks gestation, compared to the LBW children without these perinatal problems. It is speculated that the high incidence and the cause of enamel defects in sick preterm infants may be due to oxygen deprivation and mineral substitute depletion.

Structural and radiographic evaluation of four cases of tooth fusion

Four cases of tooth fusion are presented. Three of the patients were female and one male. Radiographic examination revealed union of calcified tissues with discrete root canals and a common pulp chamber in Case 3 and the converse in Case 4. The finding of fused mandibular incisors and canines in both the deciduous and permanent dentitions is described in Case 1, while in two others unilateral fused tooth masses are described which are not repeated in the permanent dentition. The dentist should be aware of the possibility of finding fused teeth on routine dental inspection and once diagnosed the patient should be informed of the potential hazards as regards plaque accumulation and varied root canal morphology.

Bilaterally inverted impaction of upper primary central incisors

A case of bilaterally inverted impaction of the upper primary centrals of a 3-year-old Chinese girl is reported. This dental anomaly rarely occurs in primary dentition. To our knowledge, this is the first report to describe such a dental anomaly.