British Journal of Orthodontics

ISSN: 0301-228X (Print) (Online) Journal homepage: http://www.tandfonline.com/loi/yjor19

Aesthetic Tooth Modification for Patients with Cleft Lip and Palate F. J. T. Burke M.Sc., M.D.S., B.D.S., F.D.S., M.G.D.S. & W. C. Shaw B.D.S., M.Sc.D., PhD., F.D.S., D.Orth., D.D.O. To cite this article: F. J. T. Burke M.Sc., M.D.S., B.D.S., F.D.S., M.G.D.S. & W. C. Shaw B.D.S., M.Sc.D., PhD., F.D.S., D.Orth., D.D.O. (1992) Aesthetic Tooth Modification for Patients with Cleft Lip and Palate, British Journal of Orthodontics, 19:4, 311-317, DOI: 10.1179/bjo.19.4.311 To link to this article: http://dx.doi.org/10.1179/bjo.19.4.311

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Date: 20 November 2016, At: 02:13

Brilish Journal of Or!hotlomics/ Vol.

19/1992/311~317

Aesthetic Tooth Modification for Patients with Cleft Lip and Palate F. J. T. BuRKE, M.Sc., M.D.S., B.D.S., F.D.S., M.G.D.S. Department of Restorative Dentistry, University of Manchester Dental School, Higher Cambridge Street, Manchester MI5 6FH

W. C. SHAW, B.D.S., M.Sc.D., PHD., F.D.S., D.ORTH., D.D.O. Unit of Orthodontics, Department of Oral Health and Development, University of Manchester Dental School, Higher Cambridge Street, Manchester M 15 6FH Received for publication July 1991

Abstract. Alongside orthodontic treatment, tooth shape modification may be indicated for teeth associated With clefts of the lip and alveolus, and in non-carious teeth, minimal tooth preparation techniques appear to be tnost appropriate. Two methods of tooth shape modification are described. In one, hybrid composite materials, bonded to tooth enamel using the acid-etch technique, may he considered to provide a permanent, low cost, aesthetically satisfactory result, often without tooth preparation and with minimal operating time. Alternatively, indirect t'eneers may he appropriate for treatment of more set,erely malformed teeth. Index words: Tooth Shape; Modification; Cleft Lip/Alveolus.

Introduction Anomalies of maxillary incisor size and form commonly accompany clefts of the lip and alveolus, and may impose limitations upon the final aesthetic result achievable by combined orthodontic and surgical procedures. The cleft side lateral incisor is commonly small and peg-shaped, and the adjacent central incisor may also be reduced in size. This tooth may also have a marked curvature of the crown and increased crown-root angulation. Since the advent of alveolar bone grafting, the maxillary canine may often be moved mesially to substitute for an absent lateral incisor. The purpose of this paper is to describe current techniques of tooth shape modification which may be used to remedy these anomalies, following the completion of orthodontic alignment.

Materials and Methods Composite restorative materials were first suggested by Bowen (1963), and in combination with the minimal tooth preparation/adhesive techniques Provided by acid etching, these materials would appear to be ideal for the minimal tooth shape modifications required in patients with clefts. It is essential that the chosen restorative material possesses sufficient strength and wear resistance to Withstand the applied masticatory forces, given that 030 1·228X;92/004000 + 00502.00

the tooth shape modification will often involve restoration of the incisal aspect. Good aesthetics is also of importance, and in this respect, microfilled composite materials, with filler particle size of 0·04 microns, have been considered to be superior. However, their resistance to fracture when used at the incisal edge has been questioned (Lambrechts et al., 1982). Alternatively, large particle composites, with filler particle size approaching 10 microns, have been considered to provide adequate strength for use at the incisal edge, but these materials are difficult to polish, giving poor aesthetics and the potential for surface staining (Jordan, 1988). The material of choice, therefore, is a hybrid composite, where particles of 1-5 microns are mixed with submicro.n particles (Fig. I). Such materials possess adequate strength for use in incisal restorations, alongside adequate 'polishability'. Light activated materials, rather than chemically activated, are indicated, because of their ease of use and long working time, the latter property being especially useful in cases of tooth shape modification where freehand build-up of the material to the desired shape may be possible. Furthermore, restorations using these materials may be expected to perform adequately in anterior teeth for at least 10 years, although this is dependent on factors such as technique of placement, size of restoration and patient's oral hygiene (O'Brien, 1989). Major reasons for eventual replacement include :u 1992 British Society for the Study of Orthodontics

312 F. J. T. Burke and W. C. Shaw

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FIG. I. Diagrammatic representation of hybrid composite materials, with large > 5 micron particles surrounded by submicron filler.

wear, secondary caries, and stammg (O'Brien, 1989), although the newer hybrid materials are considered to be colour stable (Jordan, 1988). Tooth Dimension Alterations: Principles

While achievement of the ideal tooth form may be desirable, some variation from the ideal occlusion and tooth shape may not always have a negative effect on aesthetics. However, shapes and forms may appear aesthetically superior when correctly proportioned. With regard to tooth length/width ratio, ideally the teeth should be longer than they are wide in the ratio (length to width) of 5:4, i.e. if a central incisor is 11·25 mm long, it should be 9 mm wide (Miller, 1989). However, although this is an ideal to aim for, it has been considered that it is only essential that both central incisors are the same width and that their length exceeds their width. With regard to the ratio of the size of a tooth to others in the same quadrant, the 'Golden Proportion' of 1·618 to 1·0 has been considered to be the most aesthetically pleasing proportion when viewed by the human eye. It was formulated as one of Euclid's elements, it occurs frequently in nature, and has been used through history, for example in Greek architecture (e.g. The Parthenon on the Acropolis in Athens, where the ratio of the length of the sides is in the ratio of the Golden Proportion;

FIG. 2.

Levin, 1978). An illustration of the Golden Proportion was made by Leonardo da Vinci in 1509, and Euclid showed how to divide a straight line by means of the Golden Proportion, also named the Divine Proportion by Kepler (Levin, 1978; Ricketts, 1982). A famous Greek sculptor, Phidias, used the Golden Proportion so much that it was called Phi, the Greek letter for the first part of his name. This was later shortened to pi, which is now used in the mathematical analysis of circles and spheres. Mathematical scholars through the ages have discussed this concept. In 1202, Filius Bonacci showed that a series of numbers could be obtained (Fibonacci numbers), first by adding 0 and I, to obtain a total of 1, then adding the last two numbers, giving a score of 2. Two and I are 3, and thus the numbers increase as; 0, I, 1, 2, 3, 5, 8, 13, 21, etc. When larger numbers are reached, each new addition is precisely 1·618 times the previous number, the ratio proposed in the Golden Proportion (Ricketts, 1982). When applied to tooth dimenson, the Golden Proportion would make the combined width of the centrals and laterals 1·618 times the width of the centrals alone. This principle was explained by Levin ( 1978), the width of the central incisor being in the Golden Proportion to the lateral incisor, while the width of the lateral incisor should be in a similar ratio to the canine (Fig. 2). Not only has this principle been applied to teeth, but it has been considered that the Golden Proportion may also be applied to the eyes and smile, where the central incisors dominate but with a canine or premolar dominating at the corner of the mouth. Finally, to ensure that the orientation of the anterior teeth is consistent with the remainder of the face, the anterior occlusal plane should be parallel to the interpupillary line. This may be checked using a small bite plane or disposable ruler. Ideal proportions may be aimed at and achieved by restorative techniques, but in cases of cleftrelated anomalies, some compromise may be inevitable. In this respect, measurement of teeth which are to be treated, and comparison with contralateral teeth, will assist in determining the aesthetic prognosis of treatment. While tooth shape modification may be considered by some to be the remit of the

Diagrammatic representation of The Golden Proportion.

Aesthetic Tooth Modification 313

BJO Norember /992

restorative dentist, the ease of handling of presentday light activated composite materials makes such treatment readily achievable to the orthodontic specialist, who in his everyday operating is already familiar with bonding technology. Case Report A

The patient presented for restorative treatment, following a course of treatment involving the repair of an incomplete cleft on the left side and a complete cleft on the right side, both lateral incisors being absent. Following expansion, and alveolar bone grafting on the right side, both maxillary canines Were moved mesially (Figs 3, 4, and 5). At this stage the patient was considered to be ready for tooth shape modification procedures. Consideration of the patient for such procedures showed not only the absence of lateral incisors, but also that the right maxillary central incisor had an abnormally curved disto-incisal corner; measurement showed that this tooth could be widened to the same dimension as the contralateral tooth by a distal build-up of composite. The canine teeth appeared suitable for 'lateralisation' by the mesio-

FIGS.

3 & 4.

Case A prior to orthodontic treatment.

FIG. 5. Case A, post-orthodontic treatment, showing increased curvature of distal corner of upper right central incisor, and missing lateral incisors.

incisal addition of composite, with minimal incisal contouring required to reduce these teeth slightly in length. The proposed treatment was, therefore, as follows: Addition of composite to the distal corners of the

Fws 6 & 7. Case A: completed composite build-ups on upper right central incisor and canines.

314 F. J. T. Burke and W. C. Shaw

upper central incisors, to provide a more 'ideal' shape. Minimal incisal reduction of the canine teeth, followed by addition of composite to allow these teeth to simulate lateral incisors. Examination showed that this treatment would not interfere with the occlusal relationship. The patient had previously been shown the diagnostic wax-up of the proposed tooth shape modifications. It is possible that, in future, new technology imaging equipment, for extraoral cosmetic simulation, may ultimately be of value. (Clinical Research Associates, 1991 ). Accordingly, acid-etch retained composite restorations were added to the central incisor and canine teeth, as per the proposed treatment plan, with the central incisors, being the aesthetically dominant anterior teeth, being treated first (Figs 6 and 7).

BJO Vol. /9 No. 4

FIG. 9. Case B: the upper left central incisor has a defective incisal aspect and the mesial corner of upper left lateral incisor is excessively curved.

Case Report B This patient had a repaired complete unilateral cleft of lip and palate, a palatally displaced left lateral incisor and exaggerated curvature of the left central incisor crown (Fig. 8). Following expansion and alveolar bone grafting, the anterior teeth were aligned, and it was considered that tooth shape modification procedures could be undertaken (Fig. 9). Treatment was carried out to restore the central incisor to an ideal contour, and to 'lateralize' the upper left canine (Fig. 10). Case Report C This patient had repaired complete bilateral clefts with absent lateral incisors and enamel hypoplasia affecting the left central incisor in particular (Fig. 11). Following maxillary expansion and alveolar

FIG. 8 Case B prior to orthodontic treatment.

FIG. I 0. Case 8: completed composite build-ups on upper left central and lateral incisors.

FIG.

11.

Case C prior to orthodontic treatment.

Aesthetic Tooth Modification

BJO November /992

;.Ia . I~· Case C post orthodontic treatment, showing defec•ve InCisal aspect of the upper left central incisor and labial

315

FIG. 14. Case C: side view showing Jateralisation of upper right canine.

enamel hypoplasia.

bone grafting, the maxillary canines were moved tnesially, and at this stage, tooth shape modification Procedures were commenced (Fig. 12). A directPlacement composite veneer was placed on the ~pper lef~ central in an attempt to mask t?e enamel YPoplasm and to lengthen the tooth. Usmg mesial composite build-ups, 'lateralization' of the canine teeth was carried out. The result appeared satisfactory when viewed from the front of the mouth, even though the canine teeth, when viewed from the side, could be seen to be wider than aesthetically desirable (Figs 13 and 14).

present, indirect veneers of porcelain or composite may be indicated. However, while composite buildup techniques do not often require tooth preparation, veneers require some removal of tooth substance, although indirect composite veneers may be considered to require less tooth reduction than those of porcelain. Accordingly, it has been considered that although indirect composite veneers suffer ~ ~umber of inherent limitations, they may be mdtcated where the provision of porcelain veneers should be delayed (Wilson and Wilson, 1991). Case Report D

~n Alternative Approach to Composite Build-up echniques Where considerable tooth shape modification is required, and where extensive enamel defects are

Fio_. 13. Case C; side view showing lateralisation of upper left and direct placement composite veneer to cover enamel Ypoplasia and lengthen upper left central incisor.

This patient had a repaired bilateral cleft associated with severely retroclined hypoplastic central incisors. Both lateral incisors were missing (Fig. 15). Following orthodontic repositioning of the premaxilla and lateral maxillary segments, and alveolar bone grafting, the anterior teeth were aligned

~anme

FIG. 15.

CaseD prior to orthodontic treatment.

316 F. J. T. Burke and W. C. Shaw

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FIG. I 6. Case D post orthodontic treatment with porcelain veneers placed on the central incisors and composite build-ups to lateralize the canines.

FIG. I 8. Case E post-orthodontic treatment with porcelain veneers placed on the central incisors and composite build-ups to lateralize the canines.

with the maxillary canines in the lateral incisor positions. To improve the shape of the central incisors and at the same time to mask the hypoplastic enamel, porcelain veneers were placed. The canines were 'laterilized' by placement of mesio-incisal composite build-ups (Fig. 16).

hypoplasia. To lengthen the upper right central incisor, 'lateralisation' of the upper canine teeth had previously been carried out. Accordingly, the central incisors were prepared for porcelain veneers and it may be anticipated that these will provide a satisfactory long-term result (Fig. 18). Discussion and Conclusion

Case Report E This patient had a bilateral cleft of lip and palate, absent lateral incisors and ectopic central incisors, both of which were hypoplastic (Fig. 17). Following expansion, incisor traction and alveolar bone grafting, the anterior teeth were aligned with the maxillary canines adjacent to the incisors. At this stage, examination showed that for aesthetic improvement, removal of the aesthetically poor composite veneers was indicated, followed by the provision of porcelain veneers to mask areas of

FIG. I 7.

Case 3 E prior to orthodontic treatment.

Composite resin build-ups provide a conservative approach to tooth shape modification, with advantages such as conservation of tooth structure, reversibility, low cost, low treatment time and the possibility of further incremental additions if required. While these restorations may, in the past, have been considered to be semi-permanent, present day materials show good reliability and low potential for staining, although slight marginal staining may become apparent in time, with the attendant need for polishing a:t recall visits. Furthermore, the minimal intervention nature of the technique makes it a popular treatment with patients (Asher and Lewis, 1986). Alternative treatments such as indirect composite or porcelain veneers, while less invasive than preparation for a jacket crown, still involve some tooth preparation and require unnecessary coverage of the entire facial surfaces of teeth, with the attendant problems of colour harmony and soft tissue compatibility at the gingival margin (Heymann and Hershey, 1985). However, such veneers may be indicated in cases of gross tooth shape abnormality or where the enamel is aesthetically poor due to discolouration or hypoplasia. The minimal intervention techniques described above do not preclude the placement of long-term retainers on the palatal aspect of the central incisor

BJO Not>ember /992

and canine teeth, Retention may be necessary in cases such as those described above, especially Where extensive movement of the anterior teeth has been necessary, with derotation and uprighting of teeth adjacent to the cleft. A multistrand bonded retainer may be placed and retained for as long a period as possible. Acknowledgements

The authors wish to thank Mr G. A. Smith, Consultant, Department of Restorative Dentistry, University Dental Hospital of Manchester, for his Permission to use case D, Mr Alan Jack for Producing Fig. 2, and acknowledge the co-operation of the Department of Medical Illustration, ~niversity of Manchester, in providing some ofthe Illustrations. References Asher, C. and Lewis, D. H. (1986) The integration of orthodontic and restorative procedures in cases with missing maxillary incisors, British Dental Journal. 160,241-245. Bowen, R. L. (1963) Properties of a silica-reinforced polymer for dental restorations, Journal of the American Dental Association, 66, 57-64.

Aesthetic Tooth Modification 317 Clinical Research Associates (1991) Newsletter, IS, 1-4. Heymann, H. 0. and Hershey, H. G. (1985) Use of composite resin for restorative and orthodontic correction of anterior interdental spacing, Journal of Prosthetic Dentistry, 53, 766-771. Jordan, R. E. (1988) Esthetic Composite Bonding; Techniques and Materials B. C. Becker Inc., Ontario, Canada. Lambrechts, P., Ameye, C. and Vanherle, G. (1982) Conventional and microfilled composite resins. part 11; Chip fractures Journal of Prosthetic Dentistry, 48, 527-538. Levin, E. I. (1978) Dental esthetics and the golden proportion, Journal of Prosthetic Dentistry, 40, 244-252. Miller, M. B. (1989) Diastema Closure, Reality; the information source for esthetic dentistry 4, 133-135. O'Brien, W. J. (1989) Dental Materials. Properties and selection. Quintessence Publishing Co., Inc., Chicago. Ricketts, R. M. (1982) The biologic significance of the divine proportion and Fibronacci series, American Journal of Orthodontics 81, 351-370. Wilson, N. H. F. and Wilson, M. A. (1991) Composite veneers; The indirect approach, Dental Update, 18, 185.