International Journal of Clinical Dentistry ISSN: 1939-5833 Volume 7, Number 4 © Nova Science Publishers, Inc. TOOTH ABNORMALITIES: AN OVERVIEW OF MORE THAN 20 DEVELOPMENTAL AND ACQUIRED DISORDERS Abbas Shokri1, Hamed Mortazavi2,, Maryam Baharvand, and Amir Movahhedian3 1Department of Oral & Maxillofacial Radiology, Dental School, Hamadan University of Medical Sciences, Hamadan, Iran 2Department of Oral & Maxillofacial Medicine, Dental School, Shahid Beheshti University of Medical Sciences, Tehran, Iran 3Shahid Beheshti University of Medical Sciences, Tehran, Iran ABSTRACT This paper was aimed to describe a number of tooth abnormalities, which dental practitioners in every discipline might encounter.To accomplish this review article the last versions of dental textbooks addressing the topic were first studied. Thereafter, the MeSH keywords of "tooth", "tooth abnormalities", "dental anomalies", "tooth disease", and "teeth disease" were searched in databases of Pubmed/Medline, Scopus, and EMBASE to find relevant original, review, and case reports. Finally, the subjects from articles were compared with authorized textbooks and compiled to the present review.We described 28 entities of teeth abnormalities of developmental and environmental origin as well as their treatment modalities. This article as a practical review could help dentists renew their knowledge about the field and arrive at more accurate diagnoses and treatment plan. Keywords: tooth, tooth abnormalities, dental anomalies, tooth disease, teeth disease Clinical Significance Every dental practitioner is very likely to encounter patients having abnormalities in their teeth in terms of structure, number, size, position, and morphology. Hence, appropriate knowledge of such pathologies is mandatory for correct diagnosis and treatment plan. Correspondence to: Department of Oral & Maxillofacial Medicine, Dental School, Shahid Beheshti University of Medical Sciences, Daneshjoo Blvd, Tabnak St, Chamran Highway,Tehran, Iran. Zip code: 1983963113, Work phone: +98-21-29902311, Work fax: +98-21-22403194, E-mail: [email protected] 348 Abbas Shokri, Hamed Mortazavi, Maryam Baharvand et al. INTRODUCTION Dental anomalies represent a wide spectrum of disorders divided into two subgroups: acquired and developmental abnormalities [1]. The etiology of dental anomalies has not been known thoroughly yet [2, 3], but it seems that both environmental and genetic factors could be involved [4-6]. Developmental anomalies are categorized into five groups including abnormalities in size, number, morphology, structure, and position of teeth [6-12]. This paper was aimed to describe a number of tooth abnormalities, which dental practitioners in every discipline might encounter. LITERATURE SEARCH We used various general search engines such as Google, Google Scholar, and Yahoo as well as bibliographic databases such as PubMed, PubMed central, Medline Plus, Med Know, EBSCO, Science Direct, Scopus, WebMD, EMBASE, and three authorized textbooks to find relevant topics by means of medical subject headings keywords such as "tooth", "tooth abnormalities", "dental anomalies", "tooth disease", and "teeth disease". The search was accomplished in 2013 and limited to English-language articles published over the last 50 years in both medical and dental journals. Totally, 312 articles were identified. After provisional assessment of the titles and abstracts by two reviewers, 110 articles were selected as relevant to the topic, and 80 were available for us of which 75 were used in our review. After compilation of information from relevant articles and updated textbooks, we categorized tooth abnormalities into two subgroups of acquired and developmental abnormalities with further sub classifications in each subgroup. Meanwhile, a brief treatment modality for each entity was provided. DEVELOPMENTAL DISORDERS Teeth Number Anomalies Hypodontia Lack of tooth formation is one of the most common developmental disorders with a prevalence of 1.6-9.6% in permanent teeth. However, this rate increases to 20% when third molar is considered. Hypodontia is uncommon among deciduous teeth with a prevalence of 0.5-0.9%, and if happens usually lateral incisors are involved. Missing of a primary tooth increases the chance of its succeeding permanent tooth to be missed [1]. Hypodontia is associated with microdontia, increased freeway space and the remaining deciduous teeth. The most common form of hereditary hypodontia is autosomal dominant, which the mean number of missing teeth is more than two. Except for the third molar, mandibular second premolars, maxillary second premolars and mandibular central incisors are the most commonly missing teeth [1]. Tooth Abnormalities 349 Hypodontia affects women more than men. Apart from third molars, hypodontia has a range of 0.3-11.3% according to epidemiological studies. This wide range could be attributed to racial, age, and geographical differences among studied populations [2]. Based on another study, prevalence of hypodontia in deciduous and permanent teeth was reported 1% and 3- 8.5% respectively [13]. A study on 12-18 years old children found that white people were more affected by hypodontia compared to blacks, and the most common missing tooth among the study population was third molar [8]. Treatment of hypodontia would be replacing missing teeth by prostheses. In some patients, prior orthodontic treatment helps lessen need for restorative procedures or obtain better results [1]. Hyperdontia Prevalence of supernumerary teeth is 0.1-3.8% among white people, and a little higher in Asian population. Hyperdontia affects primary teeth less often (0.3-0.8%). Although single tooth hyperdontia occurs more frequently in permanent teeth and in 95% of cases in the anterior maxilla, numerous non-syndromic supernumerary teeth are quite common in mandible. Most supernumerary teeth are seen in the jaws;however some have been reported in gingiva, maxillary tuberosity, soft palate, maxillary sinus and nasal cavity. Despite hypodontia, hyperdontia is associated to macrodontia and is twice more common as in men than women [1]. The etiology is unknown, but it is seen in some families more commonly. An association between hyperdontia and some syndromes or developmental disorders such as cleidocranial dysplasia, Gardner’s syndrome and lip or cleft palate has been suggested [13]. A study in Turkey revealed that 84 supernumerary teeth were seen in 69 radiographs, which nine of them were deciduous and 75 were permanent teeth. The most common affected site and teeth were premaxilla (67%) and mesiodense respectively. Meanwhile, supernumerary teeth had a prevalence of 2.7% among Turkish children [11]. In a study in Greek population, prevalence of hyperdontia was reported 1.8% and mesiodense was the most common type among supernumerary teeth [14]. In a similar study in India prevalence of hyperdontia was reported 1.4% [5]. Extraction of supernumerary teeth in mixed dentition is the standard treatment of hyperdontia [1]. Size Abnormalities Microdontia This term is just used when teeth are smaller than usual; when the jaw is bigger than usual as a result of spacing between teeth and teeth look smaller this is called relative microdontia, which represents jaw enlargement but not true microdontia. True generalized microdontia is uncommon, but it can occur as a sporadic finding in Down syndrome, pituitary dwarfism and some rare hereditary anomalies. Single microdontia is often seen in maxillary lateral incisors, which usually has a peg-shaped crown on a normal-height root. The prevalence of microdontia has a range of 0.8-8.4% in different populations and it seems to be of autosomal dominant inheritance with incomplete penetration [1]. 350 Abbas Shokri, Hamed Mortazavi, Maryam Baharvand et al. Solitary microdontia often involves maxillary lateral incisors and third molars. In a survey in Japan, 1.9% of students had microdontia [15]. No treatment is necessary unless for esthetic reasons. In this case, peg-shaped lateral incisors could be restored by porcelain restorations [1]. Macrodontia The term macrodontia (megalodontia, megadontia) is justified when teeth are larger than usual, and not when teeth with normal size are placed in a small jaw or in case of gemination and fusion. True generalized macrodontia may be along with gygantism. True localized macrodontia may be seen in facial hemihypertrophy. The etiology is unknown, and there is no need for any treatment unless for esthetic reasons [1, 16]. Positional Anomalies Transposition This is a situation in which two teeth displace when teeth are not in their proper position in dental arch. Transposition is common in canines and first premolars followed by lateral incisors. Sometimes second premolar erupts between the first and second molar. Transposition of central and lateral incisors is rare. Transposition has not been reported among primary teeth. This anomaly can be associated with hypodontia, supernumerary teeth and remaining deciduous teeth [16]. A studyon Turkish population aged 12-27 years old demonstrated the prevalence of transposition as 0.27% with the female: male ratio of 2.2:1. In addition, the most common transposition occurred between canine and lateral incisors (60%), which was more frequent in the left side [17]. In another study, 88% of transpositions were unilateral with greater prevalence in maxilla than mandible. Moreover, the most common transposition occurred between maxillary canine and first premolar (83%) followed by maxillary