A midline diastema usually is part of normal dental development during the mixed dentition. However, several factors can cause a diastema that may require intervention. An enlarged labial frenum has been blamed for most persistent diastemas, but its etiologic role now is understood to represent only a small proportion of cases. Other etiologies associated with diastemas include oral habits, muscular imbalances, physical impediments, abnormal maxillary arch structure, and various dental anomalies . A possible genetic basis has been suggested for diastema, with a greater role of environmental factors in the Black, than the White population .
The incidence of midline diastema varies greatly with the age-group, gender, population and race. This condition is very common in the paediatric age-group at the early stages of dental development . Naturally, after the eruption of the permanent teeth, the gap closes in majority of them. However, where the diastema remains after the eruption of the permanent incisors and canine, such may not close on its own . Oesterle and Shellhart, in 1999, reported 97% incidence in 5-year-old patients, and this decreased with age . While midline diastema was found in 37% adolescent in Nigeria
There are divergent views on diastema. The aesthetic importance varies in relation to culture, age group and racial background. Influenced by such culture and social forms, individuals without a diastema may desire to have it created through cosmetic dentistry, while some others with diastema would rather want it closed or removed, because they find it aesthetically displeasing. [5, 6].
In Africa, maxillary midline diastema is regarded as an attractive dental feature, a sign of beauty, especially in the females, and is used as notable successful trademark. Meanwhile, a study by Oboro et al in 2008 reported that majority of patients interviewed did not support the artificial creation of midline diastema .
This study aimed to determine the prevalence, heredity and acceptance of diastema in a sample of Iraqi students in institute of medical technology in Baghdad.
Materials and Methods
Two hundred students were examined in this study,100 females and 100 males whose age range was 18-21 years. They were selected at random, and examined by millimeter vernier after sitting comfortably on dental chair and reflection of upper and lower lips by lip and cheek retractor, the space between central incisors more than 0.5mm was regarded as median diastema . All sample students are subjected to same criteria that should not have congenital deformity like cleft lip and /or palate, not had trauma to anterior teeth, also should not have caries or filling or veneer crowns in anterior region.
Participants were required to provide information on: the presence or absence of diastema; their perception and preference for diastema; and, the presence or absence of diastema in their parents who are invited to undergo the same examination and same criteria bymillimeter vernier after sitting comfortably on dental chair. The incidence and percentage of diastema were determined by simple percentage method, subjected to statistical analysis using the chi-square, with the SPSS software package.
Findings from the study showed that 28% of the study sample students had midline diastema (Table 1). Out of this percentage, the incidence of maxillary midline diastema was 22.5%, mandibular midline diastema was 2.3%, and that of co-existing maxillary and mandibular midline diastema was 3.2% (Table 2a).
Previous studies have shown that there are variations in the incidence of this dental feature from one population to another, among people of different racial background, age-group, gender, as well as the importance attached to it by people of different cultures [2,3,8].
Factors have been implicated as the possible aetiology of diastema among which are the presence of a superior labial frenum, a mismatch between teeth and jaws, tongue thrusting, or an abnormal jaw bone structure [1, 9,10].
In the current study of diastema in a sample of students in institute of medical technology in Baghdad, an incidence of 28% was found, of which 22.5% had maxillary midline diastema, 2.3% had mandibular midline diastema, and 3.2% had both maxillary and mandibular midline diastema.
The incidence of median diastema found in current study is close to that found in Kuwait (26.8%) . A study among Turkish population showed that midline diastema was observed in (4.5%) of the patients and it was almost equally distributed between the females and males, 35 in females and 33 in males  ,whereas a study among Tanzanians found the incidence to be 26%, 11% and 8% for maxillary, mandibular, and both arches midline diastema respectively (13). These figures were lower in these populations than in the current study. The percentage of median diastema 12.59 % is considerably higher in a study done in Pakistan  as compared to prevalence in United Kingdom 3.4 % of Caucasians and 1.6 % of South Indians.
This difference could be attributed to the difference in inclusion criteria, sampling technique or genetic predisposition.
Occurrence of diastema was less in the females, as 16 (16%) of the female sample had diastema, while only 40 (40%) of the male sample had it. This disagrees with an earlier study by Oji and Obiechina (1994) which found diastema to be more prevalent in females .
Studies in different population groups consistently showed that maxillary midline diastema occurs more frequently than mandibular midline diastema [2,3,14]. This was also observed in the present study where out of the 28% incidence of midline diastema, 22.5% was maxillary, 2.3% was mandibular, and the remaining 3.2% comprised of coexisting maxillary and mandibular midline diastema.
While the incidence of mandibular midline diastema in this study was lower than that of diastema occurring in both arches, the study by Athumani and Mugonzibwa (2006) showed higher incidence in the Tanzanian population .
Meanwhile, mandibular midline diastema occurred more in males 9(22.5%) than females 2 (12.5%), just as maxillary midline diastema occurred more in females 13(81.2%) than males 26 (65%).
Cultural influence was one of the reasons why some people considered diastema as a disfiguring dental feature requiring treatment, while some others saw it as an advantage to their personality, an enhancement of their beauty, giving them an admirable look and smile [16,17]. In this current study about half students who showed median diastema 26 (46.4%) were satisfied and saw it not affecting the beauty and refused any kind of the treatment by orthodontic ,cosmetic light cure or ceramic crowns, while others 30(53.6%) were dissatisfied and seeking treatment.
Fourteen out of sixteen(87.5%) of females found with median diastema were unpleasant ,while only 16 out of 40 males ( 40%) were dissatisfied , this could be attributed to sex difference in esthetic interest at this age in our society.
However, people that see diastema as an aesthetic problem have the opportunity of closing the space. Procedures for closure include frenectomy, orthodontics, restorative dentistry, use of veneers, and various combinations of several dental treatments [1,18,19].
The heredity of midline diastema from the present study was 62.5%, with a equal probability for both males and females (62.5%) to inherit it.
Variations abound in the occurrence of midline diastema from one population to the other. This study shows that maxillary midline diastema occurs more frequently than mandibular midline diastema, and that females are more likely to have a maxillary midline diastema, while males are more likely to have a mandibular midline diastema. Diastema runs in families.
1. Koora K, Muthu MS, Rathna PV. Spontaneous closure of midline diastema following frenectomy. Journal of Indian Society of Pedodontics and Preventive Dentistry 2007;25:23-6
2. Nainar SMH and Gnanasundaram N. Incidence and etiology of midline diastema in a population in South India. The Angle Orthodontics 1989;59:277-282.
3. Oji C and Obiechina AE . Diastema in Nigerian society. Odonto- Stomatologie Tropicale 1994;17,68,4-6.
4-Mohammad KhurshedAlam The multidisciplinary management of median diastema Bangladesh Journal of Medical Science , 9, No 4 (2010)
5. Oesterle LJ and Shellhart WC. Maxillary midline diastema: a look at the causes. Journal of American Dental Association 1999;130:85-94.
6-Hang WJ, Creath CJ. The midline diastema: a review of its etiology and treatment.Pediatr Dent. 1995 May-Jun;17(3):171-9. Review.
7-Oboro HO, Umanah AU, Chukwumah NM, Sede M . Creation of artificial midline maxillary diastema: opinion of Nigerian dentists. (online) 2008 (cited 2009 Nov 16).
8. Almog D, Marin CS, Proskin HM, Cohen MJ, Kyrkanides S. The effect of esthetic consultation methods on acceptance of diastema closure treatment plan. Journal of American Dental Association 2004;135(7):875-881.
9. Bergström K, Jensen R, Mårtensson B. The effect of superior labial frenectomy in cases with midline diastema. American Journal of Orthodontics 1973;63(6):633-638.
10. Tait CH. The median frenum of the upper lip and its influence on the spacing of the upper central incisor teeth. Dent Cosmos 1934;76:991-992.
11. S. Al Enezi1 - Dr. E Zaatar1 - Dr. N O Salako2. Prevalence of Selected Dental
Anomalies in Kuwaiti OrthodonticPatients.orthodontics journal; DENTAL NEWS, Volume IX, Number IV, 2002
12-MevlutCelikoglu 1, SemaAkpınar 1, Ibrahim Yavuz 2 The pattern of malocclusion in a sample of orthodontic patients from Turkey.Journal section: Clinical and Experimental Dentistry doi:10.4317/medoral.15.e791
13.Athumani AP and Mugonzibwa EA. Perception on diastema medialle (mwanya) among dental patients attending Muhimbili National Hospital. Tanzania Dental Journal 2006;12 (2)50-57.
14. HamedullahJan ,Sadia Naureen, AyeshaAnwar: Frequency and etiology of midline diastema in orthodontic patients reporting to armed forces institute of dentistry Rawalpindi Pakistan: Armed Force Medical Journal 2010;1,4-10
15. Gass JR, Valiathan M, Tiwari HK, Hans MG, Elston RC. Familial correlations and heritability of maxillary midline diastema. American Journal of Orthodontics and Dentofacial Orthopedics 2003; 123 (1): 35-39. 16. Kaimenyi JT. Occurrence of midline diastema and frenum attachments among school children in Nairobi, Kenya. Indian Journal of Dental Research 1998;9:67-71
17. Onyeaso CO Prevalence of malocclusion among adolescents in Ibadan, Nigeria, [2004, 126(5):604-607].
18. Gkantidis N, Kolokitha O, Topouzelis N. Management of maxillary midline diastema with emphasis on etiology. Journal of Clinical Paediatric Dentistry 2008;32(4):265-272.
19. Bram G. Diastema: getting rid of gaps between teeth. (online) 2005(cited 2009 Nov 16).