Retrospective analysis of factors influencing the eruption of delayed permanent incisors after supernumerary tooth removal

Transcription

1 Retrospective analysis of factors influencing the eruption of delayed permanent incisors after supernumerary tooth removal R.A.E. BRYAN*, B.O.I. COLE**, R.R. WELBURY* ABSTRACT. Aim This was to assess the predictability of eruption of delayed permanent incisors after supernumerary removal and creation of adequate space, in relation to: root maturity, degree of vertical impaction, and degree of angulation of impaction. Methods The dental records of children with supernumerary teeth delaying the eruption of permanent incisors were analysed. The type of a supernumerary tooth, its location and position were recorded, along with the stage of root maturation, angulation and vertical distance of impaction of the permanent incisor. At the initial surgery, the unerupted supernumerary tooth and any retained primary incisors were removed. The unerupted permanent incisor was not exposed. If necessary, the maxillary primary canines were removed to create sufficient space for eruption of the delayed permanent tooth. A secondary surgical procedure was planned after 18 months if there was no significant progress of the permanent tooth towards eruption. Statistics All data were entered onto a Microsoft Excel spread sheet and analysed using Fisher s Exact Tests throughout due to the small numbers. Results Sixty-six supernumerary teeth were removed, 22 from boys and 44 from girls with ages ranging from 6 to 10 years 6 months at the time of surgery. Primary canines were extracted in 59.1% of cases. Spontaneous eruption occurred in 89.4% of delayed permanent teeth. The mean time to eruption was 9.2 months (median = 7 months). There was no statistically significant association between tooth eruption and root maturity or the degree of vertical impaction. There was an association between eruption and the degree of the angle of impaction of the permanent incisor (p<0.05). Conclusion The majority of delayed permanent teeth erupt spontaneously if sufficient space is available or created at the time of removal of the unerupted supernumerary. The angulation of impaction of the permanent incisor is associated with a delay in eruption. KEYWORDS: Supernumerary teeth, Delayed incisor eruption. Introduction Supernumerary teeth are those that are additional to the normal complement. They occur in both the primary and permanent dentitions, and in any region of either dental arch. The aetiology is not clearly understood, and their classification is usually based on their morphology and location within the arch. Several hypotheses have been suggested for the development of supernumerary teeth. Both environmental factors and a genetic component are thought to be associated, with siblings and twins more often affected [Liu, 1995; Di Biase, 1969]. *Department of Child Dental Care, Glasgow Dental Hospital and School, Glasgow, Scotland **Department of Child Dental Health, Newcastle Dental Hospital and School, Newcastle, England r.bryan@leeds.ac.uk Prevalence. There is a wide range of reported prevalence depending on the method of detection, the population assessed and their age. In those studies where radiographs have not been used, the prevalence is greatly underestimated. Brook [1974] surveyed approximately 2,000 predominately Caucasian schoolchildren, and reported a prevalence of 2.1% in the permanent dentition and 0.8% in the primary dentition. The occurrence of supernumeraries shows a predilection for males (2:1) [Brook, 1984]. Supernumeraries are more often found in the maxilla, with a ratio of maxilla to mandible of 9:1, and are especially frequent in the maxillary incisor region [Luten, 1967; Mitchell and Bennett, 1992]. They occur singly in approximately 76-80% of cases, doubly in 12-23% and as multiples in less than 1% [Luten, 1967]. Multiple supernumeraries are associated with several syndromes, most common of these being cleft lip and palate, cleidocranial dysostosis and Gardners 84 EUROPEAN JOURNAL OF PAEDIATRIC DENTISTRY 2/2005

2 DELAYED INCISOR ERUPTION WITH SUPERNUMERARY TEETH syndrome, with reported frequencies of up to 22% [Garvey et al., 1999]. Classification. Supernumeraries are classified according to their morphology and location. In the primary dentition, they are usually of normal morphology (supplemental) or conical, and generally erupt. In the permanent dentition, the morphology is more varied. They are classified as conical, tuberculate, supplemental or odontome. Conical supernumeraries are the most common form [Liu, 1995; Rajab and Hamdan, 2002], accounting for approximately 75%, followed by tuberculate (12%), supplemental (7%) and odontomes (6%). True midline conical supernumeraries are often referred to as mesiodens. Their orientation is described as vertical (i.e. normal), inverted (upside-down) or transverse (horizontal). Several studies have shown inverted supernumeraries to be the most common [Tay et al., 1984; Liu, 1995] although Rajab and Hamdan [2002] showed 83% to have a normal vertical orientation. Diagnosis. The presence of supernumerary teeth may be diagnosed as the result of a clinical problem, or may be an incidental finding on a radiograph. Clinical problems may be associated with both erupted and unerupted supernumeraries, and include the following: - failure of eruption of a permanent tooth; this occurs most frequently in the maxillary incisor region. Tuberculate supernumeraries are more likely to impede eruption, especially if they are palatally placed [Mason et al., 2000], - displacement or rotation of a permanent tooth [Howard, 1967], - crowding, especially in the maxillary lateral incisor region with the eruption of a supplemental incisor,. - abnormal diastema, associated with an erupted or unerupted mesiodens, - dilaceration, delayed or abnormal root development; occasionally, the presence of a supernumerary may lead to resorption of the roots of adjacent permanent teeth, - cyst formation, - eruption into the nasal cavity of an inverted supernumerary. Treatment. The options for dealing with supernumerary teeth depend on their position and orientation, the age of the patient and any associated clinical problems. Early surgical intervention carries the risks of psychological disturbances to the child, and damage to the adjacent unerupted developing teeth. Late intervention may be associated with loss of the eruptive potential of the unerupted permanent teeth, loss of anterior arch space and curvature, and a midline shift, with a subsequent need for orthodontic treatment. The aim of this study was, therefore, to assess the predictability of eruption of delayed permanent incisors, after supernumerary removal and creation of adequate space, in relation to: root maturity, degree of vertical impaction, and degree of angulation of impaction of the permanent tooth, and the type, location and orientation of the supernumerary tooth removed. Materials and methods Children were assessed in the Department of Child Dental Health at Newcastle Dental Hospital following referral for the management of unerupted supernumerary teeth, either as a chance finding or as the result of the delayed eruption of a permanent incisor. The data for children attending between May 1994 and December 2000 were identified from the Paediatric Dentistry National Audit Package [Royal College of Surgeons of England, 2000]. The children were included in the present study if they fulfilled the following criteria: - medically fit and well, - delayed eruption of a permanent incisor associated with one or more unerupted supernumerary teeth. In this context, delayed eruption is defined as a tooth delayed more than 6 months beyond the eruption of its altemere, or beyond the eruption of the next tooth in the series. Fifty-five patient records were available for analysis. All children had been assessed and treatment planned by a paediatric dentist. Details of their hospital number, gender, date of birth, date of first assessment, and reason for referral were identified from the dental hospital records, and entered onto specially prepared data collection sheets. Radiographic assessment and localisation of the supernumerary and unerupted permanent teeth were completed by two observers using panoramic and maxillary standard occlusal views. Some children also had parallax periapical views taken. From the radiographs the following assessments were made: - the permanent tooth (or teeth) delayed (FDI notation), - the type of supernumerary (conical/tuberculate/ odontome/supplemental), - the location of the supernumerary (maxillary central/maxillary lateral/mandibular central/ mandibular lateral), - the orientation of the supernumerary (inverted/ EUROPEAN JOURNAL OF PAEDIATRIC DENTISTRY 2/

3 R.A.E. BRYAN, B.O.I. COLE, R.R. WELBURY horizontal/normal), - the total number of supernumeraries (one/two/three or more), - the stage of maturation of the root of the delayed permanent tooth (divergent/parallel/convergent/ closed), - the vertical distance from the nasal spine to the lowest point of the incisal edge of the unerupted permanent tooth, - the angle of the long axis of the unerupted permanent tooth to the mid-sagittal plane. The initial surgery was carried out under general anaesthetic. At the time of surgery, the unerupted supernumerary tooth, and any retained primary incisors, was removed. The unerupted permanent tooth was not exposed. If necessary, the primary canines were also removed to create sufficient space to allow spontaneous eruption of the delayed permanent tooth. Following surgery, orthodontic treatments included space maintenance or the creation of space in the region of the delayed permanent incisor with either a removable or fixed orthodontic appliance. All cases were reviewed 3-6 monthly. The date of eruption of the permanent tooth was recorded as the date of the recall appointment at which the tooth was first noted as being present in the mouth. A second surgical procedure was planned if 18 months after the initial surgery there appeared to be no significant progress of the permanent tooth towards eruption. This consisted of either soft tissue removal to expose the permanent tooth, or exposure via a mucoperiostial flap, with or without bonding of an orthodontic bracket and gold chain attachment. Some cases had additional space created by removal of the primary canines at this stage, and some required removable or fixed orthodontic appliances to maintain or create further space. The time from the second surgery to eruption was recorded. No case required a third intervention. Statistics. All data were entered onto a Microsoft Excel spread sheet and analysed using Fisher s Exact Tests throughout due to the small numbers. Results Sixty-six supernumeraries were identified in the 55 children. The children s ages ranged from 4 years 7 months to 10 years 6 months at the time of their initial assessment, with 22 supernumeraries in males and 44 in females (male:female = 1:2). Of the 55 children, 44 had 1 supernumerary, 10 had 2, and 1 had 3 or more. Table 1 shows the distribution of type, location and orientation of the supernumeraries. The vertical distance of the incisal edge of the delayed permanent incisor from the anterior nasal spine was grouped into 5 mm bands for ease of analysis. Table 2 shows the distribution of the vertical distances, angulation and apical development of the delayed permanent incisor. None was at more than 60 to the vertical as measured on the panoramic radiograph. Maxillary central incisors were the most frequently delayed permanent teeth, 62/66 (94%). Only 4 maxillary lateral incisors were affected, and no mandibular incisors. The ages ranged from 6 years to 10 years 6 months at the time of the surgery. Supernumerary type Number % Conical Tuberculate Odontome Supplemental Supernumerary location Maxillary central Maxillary lateral Supernumerary orientation Inverted Horizontal Normal TABLE 1 - Distribution of type, location and orientation of a series of supernumerary teeth in an English child population. Vertical distance (mm) Number % Angulation of long axis <30 degrees degrees Apical development Divergent Parallel Convergent TABLE 2 - Vertical distance, angulation and apical development of the delayed permanent incisors in relation to supernumerary teeth. 86 EUROPEAN JOURNAL OF PAEDIATRIC DENTISTRY 2/2005

4 DELAYED INCISOR ERUPTION WITH SUPERNUMERARY TEETH Additional space was created at the time of the first surgery by extraction of the primary canines in 33/55 (60%) cases. A space maintainer was fitted in 10 cases (15.2%), and additional space created with a fixed or removable appliance in 21 cases. Spontaneous eruption occurred in 59 of the 66 delayed permanent teeth (89.4%), without the need for further intervention. Eruption occurred in less than 12 months in 42 teeth (66%), 11 (18.6%) in months, and 6 (10.2%) in months. The mean time from first instance of surgery to eruption was 9.2 months (median = 7 months, range 1-27 months). In the seven cases where further treatment was needed, this was carried out between 18 and 34 months after the initial surgery. In three children, only soft tissue removal was required. In the remaining four cases, a mucoperiostial flap was raised and either apically repositioned or an attachment bonded to the unerupted incisor prior to replacement of the flap. Five of the secondary surgical procedures were carried out under general anaesthesia, and the remaining two under local analgesia. Only one child required the creation of additional space by the extraction of primary canines. Following the secondary surgical procedure, space was controlled with a maxillary fixed orthodontic appliance in four instances. The time from secondary surgery to eruption ranged from 1 to 25 months, with four teeth erupting within 3 months. The mean time to eruption was 8.1 months (median 3 months). For the whole group, there was no statistically significant association between tooth eruption and vertical distance or apical development (Table 3). However, there was a statistically significant association between eruption and the angle of the long axis of the permanent incisor (p=0.048). In those teeth that did not erupt, four had an angle of <30, compared with three at In contrast, in those teeth that did erupt, 53 (90%) had an angle of <30, compared with only 6 (10.2%) with an angle of Of the teeth that erupted spontaneously (Table 4), there was a statistically significant difference between time to eruption and vertical distance (p=0.022). There were 42/59 teeth that erupted within the first 12 months from initial surgery (71%), and 25 of these (60%) were 16 mm or more from the nasal spine (i.e. closer to the alveolar ridge). Neither the angle of the long axis nor the apical development were statistically significantly associated with the time to eruption in those teeth which erupted spontaneously. The effect on the subsequent eruption of the permanent teeth of the type, location and orientation of the supernumerary teeth prior to their removal could not be assessed because of the small numbers involved. The type of supernumerary associated with the teeth that did not spontaneously erupt after surgery was 4 conical, 2 tuberculate and 1 odontome. One supernumerary was inverted; 4 were single and 3 were double. Tooth erupts? Fisher s Yes % [N] No % [N] Exact Test Vertical distance (mm) [9] 14.3 [1] [21] 28.6 [2] [15] 57.1 [4] [14] Angulation <30 degrees 89.8 [53] 57.1 [4] degrees 10.2 [6] 42.9 [3] Apical development Divergent 32.2 [19] 28.6 [2] Parallel 42.4 [25] 57.1 [4] Convergent 25.4 [15] 14.3 [1] TABLE 3 - Association between tooth eruption and vertical distance, angulation and apical development of the permanent incisors in relation to supernumerary teeth. EUROPEAN JOURNAL OF PAEDIATRIC DENTISTRY 2/

5 R.A.E. BRYAN, B.O.I. COLE, R.R. WELBURY Eruption times (% [N]) Fisher s Exact Test months months months Vertical distance (mm) [8] [1] [9] 72.7 [8] 66.6 [4] [12] 18.2 [2] 16.7 [1] [13] 9.1 [1] Angulation <30 degrees 92.9 [39] 81.8 [9] 83.3 [5] degrees 7.1 [3] 18.2 [2] 16.7 [1] Apical development Divergent 26.2 [11] 35.4 [4] 66.7 [4] Parallel 42.9 [18] 45.5 [5] 33.3 [2] Convergent 31.0 [13] 18.2 [2] TABLE 4 - Association between time to eruption and vertical distance, angulation and apical development in the permanent incisors that erupted spontaneously following supernumerary removal [N=59]. Discussion Previously reported studies have indicated a prevalence ratio of 2:1 male:female. In this study, however, the complete opposite was found. The distribution of single or multiple supernumeraries was similar to that reported by Luten [1967] with 80% single, 18.2% double and 1.8% multiple. The distribution of the type of supernumerary was similar to Liu [1995] and Rajab and Hamdan [2002], with conical supernumeraries occurring most frequently (57.6%). In our study normally orientated supernumeraries occurred most frequently (63.6%), as reported by Rajab and Hamdan [2002]. Although statistical significance was not reached for vertical distance and apical development, there may still be a clinically significant association. The numbers are small in this study and subtle effects may have been missed due to a lack of statistical power. Munns [1981] showed that irrespective of the degree of displacement of the unerupted incisor, the prognosis for being able to bring it into a good arch position and occlusal relationship was better with early diagnosis and treatment. Howard [1967] found that the amount of apical displacement of the unerupted incisor was related to whether it had erupted spontaneously following the removal of the supernumerary, or had required further exposure. Mitchell and Bennett [1992] showed a trend toward an increase in the time taken for an incisor to erupt with an increase in the initial degree of its displacement. This trend was not statistically significant, possibly due to the relatively small numbers of teeth in this study. In a retrospective study of unerupted maxillary incisors associated with supernumerary teeth, Mason et al. [2000] concluded that the maturity of the unerupted incisor root was an important factor in the outcome following removal of the supernumerary. They suggested that all unerupted incisors should be exposed (with or without bonding and orthodontic traction). However, this may be associated with loss of supporting bone and increased scar tissue formation. Our study found no such relationship with apical maturity. However, it should be noted that the numbers in our study are small even though they were cases collected over six years in a major referral dental hospital. Studies of this nature are not easy to complete because of the low prevalence recorded in individual centres. Patchett et al. [2001] showed a statistically significant difference in the eruption of delayed permanent incisors depending on the type of supernumerary removed. Fifty-five out of eighty seven (63%) incisors erupted spontaneously following the removal of a conical supernumerary. In the group from whom tuberculate supernumeraries had been removed, only 31/85 (36%) permanent incisors erupted spontaneously. Of the teeth requiring further treatment, 46 (54%) were surgically exposed. In this study, there had been no assessment of 88 EUROPEAN JOURNAL OF PAEDIATRIC DENTISTRY 2/2005

6 DELAYED INCISOR ERUPTION WITH SUPERNUMERARY TEETH the degree of crowding present prior to supernumerary removal, nor measurement of the initial displacement of the permanent incisor. A similar study in Scotland [Foley, 2004] showed 73% spontaneous eruption of delayed permanent teeth, with a significant difference following the removal of conical or tuberculate supernumeraries. In our study, a greater angle of displacement of the permanent tooth from the midline sagittal plane appears to lead to a greater delay in eruption (p=0.048). This has clinical significance in treatment planning and predicting eruption. With regard to time taken to eruption and angular displacement, some 73% of teeth erupted spontaneously within 0-11 months in the <30 group compared with 50% in the group. However, there was insufficient statistical power to detect differences between the eruption times, and collection of larger numbers of cases from additional centres using the same assessment criteria is required. Sufficient space availability, either naturally at the time of the initial examination or its incorporation into any treatment plan by the extraction of primary canines at the time of the removal of the supernumerary, can result in the eruption of most of the delayed permanent incisors without the need for further intervention. This concurs with the recommendation of Mitchell and Bennett [1992]. Of the seven cases that required further surgery in this study, only four needed a mucoperiosteal flap to be raised. The others were treated by localised soft tissue removal. It is possible that earlier soft tissue removal when a tooth is approaching eruption may result in earlier eruption. This is something to consider in future research. Conclusions The majority of delayed permanent incisors erupt spontaneously if sufficient space is created at the time of removal of the supernumerary tooth and maintained postoperatively. The angulation of the delayed tooth appears to be important in trying to predict eruption. However, more data are required from coordinated multi-centre studies to try and elucidate the important predictors of the prognosis for eruption. Acknowledgements The authors would like to thank Andrea Sherriff for the statistical analysis. References Brook AH. Dental anomalies of number, form and size: their prevalence in British schoolchildren. J Int Assoc Dent Child 1974 Dec;5(2): Brook AH. A unifying aetiological explanation for anomalies of human tooth number and size. Arch Oral Biol 1984;29(5): Di Biase DD. Midline supernumeraries and eruption of the maxillary central incisor. Dent Pract Dent Rec 1969 Sep;20(1): Foley J. Surgical removal of supernumerary teeth and the fate of incisor eruption. Eur J Paediatr Dent 2004 Mar;5(1): Garvey MT, Barry HJ, Blake M. Supernumerary teeth--an overview of classification, diagnosis and management. J Can Dent Assoc 1999 Dec;65(11): Howard RD. The unerupted incisor. A study of the postoperative eruptive history of incisors delayed in their eruption by supernumerary teeth. Dent Pract Dent Rec 1967 May;17(9): Liu JF. Characteristics of premaxillary supernumerary teeth: a survey of 112 cases. ASDC J Dent Child 1995 Jul- Aug;62(4): Luten JR Jr. The prevalence of supernumerary teeth in primary and mixed dentitions. J Dent Child 1967 Sep;34(5): Mason C, Azam N, Holt RD, Rule DC. A retrospective study of unerupted maxillary incisors associated with supernumerary teeth. Br J Oral Maxillofac Surg 2000 Feb;38(1):62-5. Mitchell L, Bennett TG. Supernumerary teeth causing delayed eruption--a retrospective study. Br J Orthod 1992 Feb;19(1):41-6. Munns D. Unerupted incisors. Br J Orthod 1981 Jan;8(1): Patchett CL, Crawford PJ, Cameron AC, Stephens CD. The management of supernumerary teeth in childhood--a retrospective study of practice in Bristol Dental Hospital, England and Westmead Dental Hospital, Sydney, Australia. Int J Paediatr Dent 2001 Jul;11(4): Rajab LD, Hamdan MA. Supernumerary teeth: review of the literature and a survey of 152 cases. Int J Paediatr Dent 2002 Jul;12(4): Tay F, Pang A, Yuen S. Unerupted maxillary anterior supernumerary teeth: report of 204 cases. ASDC J Dent Child 1984 Jul- Aug;51(4): Royal College of Surgeons of England. The Paediatric Dentistry National Audit Package. London: EUROPEAN JOURNAL OF PAEDIATRIC DENTISTRY 2/