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Clinical Section |
Department of Orthodontics, St. George's Hospital, London SW17 0QT, U.K.
Introduction
This award was established in 1988, the first year in which the Membership in Orthodontics was examined at the Royal College of Surgeons of England. It was presented to the college by the British Society for the Study of Orthodontics. A medal and certificate are presented to the candidate at the examination with the highest overall mark in Part II of the examination. The prize is only awarded if the examiners believe the candidate's performance is of a sufficiently high standard.
As part of the examination, which includes a long clinical case, diagnostic tests, oral examinations and a written paper, the candidate must present three personally-treated, fully documented cases on which the candidate is examined orally. Details of two of the treated cases are presented in this paper.
Case Report 1
A 12-year 2-month-old Caucasian female was referred by her General Dental Practitioner complaining of her overlapping front teeth.
On examination, she presented with a Class II division 2 incisor relationship on a mild skeletal II base with bimaxillary retrognathia. The FMPA and lower anterior face height was increased. Clinically, her lips were apart at rest, with upper and lower lip well behind Ricketts' aesthetic ‘E’ line. The nasolabial angle was obtuse.
Intra-oral examination revealed that she was in the permanent dentition stage with good oral hygiene and dental condition. Her lower arch had mild crowding anteriorly with retroclined incisors and upright canines. The buccal segments were generally well aligned with mild mesiolingual rotations of the first and second premolars. The upper labial segment was moderately crowded with retroclined incisors. The upper left canine was mesially angulated and the upper right, distally angulated. Both upper buccal segments were well aligned. The upper lateral incisors were measured to be slightly diminutive relative to their counterparts and a Bolton tooth size discrepancy revealed the maxillary labial segment to be deficient by 3 mm.
In occlusion, the incisor relationship was Class II division 2, with an overjet of 4 mm and an increased overbite, complete to the palate. The first permanent molars in the left buccal segment were in crossbite. The molar relationship was full unit Class II on the right and three-quarter unit Class II on the left. Both upper and lower centre lines were coincident with the facial midline (Figure 1a–h
).
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The panoramic radiograph revealed congenital absence of both lower third molars. The upper third molars were developing in a normal position. The upper anterior occlusal radiograph confirmed the upper incisors to have normal root morphology. The lateral cephalogram confirmed a mild skeletal II pattern. Using an Eastman conversion, the ANB difference was 5 degrees and the Wits analysis difference was 4 mm. The upper incisors were retroclined at 100 degrees to the maxillary plane and the lower incisor were inclined at 84 degrees to the mandibular plane. The inter-incisor angle was increased at 144 degrees and the lower incisor tip was just behind the centroid of the upper incisor. Cephalometric analysis is presented in Table 1.
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For this patient, the Dental Health Component (DHC) score on the Index of Treatment Need (IOTN) was 4d as there was a contact point displacement of greater than 4 mm. The pretreatment weighted Peer Assessment Rating (PAR) score was 32.
The aims of treatment were:
The treatment plan was as follows:
Treatment was planned without extractions as space analysis calculated 8 mm of space requirement in the upper arch. This was gained using extra-oral traction to distalise the buccal segments. Active treatment required 22 visits over a 26-month period. The upper removable appliance was worn for the first 8 months and combination pull safety headgear was fitted once the unilateral crossbite had been corrected. Headgear wear was maintained throughout the remaining treatment period. Once the buccal segment relationship had been corrected, bands were cemented to the upper first molars and the headgear was adjusted to apply an intrusive high pull force. Pre-adjusted Edgewise brackets (0•022 x 0•028-inch slot, Andrew's prescription) were bonded to the upper teeth and levelling and alignment was achieved using superelastic nickel titanium wires. The lower fixed appliance was commenced when a round 0•018-inch stainless steel arch wire was ligated in the upper arch. The patient's original archform was maintained, whilst some expansion was allowed in the upper molar region to maintain correction of the unilateral cross bite. The arch wire sequence was progressed until 0•019 x 0•025-inch stainless steel wires were ligated in both arches. After allowing the flat arch wires to be expressed, overbite reduction was achieved by bending an increased curve of Spee in the upper archwire. The second permanent molars had been included in the appliance by this stage.
A mid-treatment lateral cephalogram was taken. This showed that lower incisor inclination had increased by 3 degrees to the mandibular plane. Light interdental stripping of the lower labial segment was undertaken and the 0•019 x 0•025-inch stainless steel wire was religated with lingual crown torque. Additional palatal root torque was applied to the upper incisors. Intra-traction was necessary in the upper buccal segments to close space and provide anchorage for the palatal root torque applied to the upper labial segment. A 1-mm centre line discrepancy was corrected using unilateral light Class II traction on the right side only together with an asymmetric anterior elastic.
Following debond, a palatal fixed retainer in 0•0175-inch twistflex stainless steel was bonded to the upper incisors and a similar lingual fixed retainer was bonded to the lower incisors and canines. In addition, an upper Hawley style retainer was fitted to maintain arch width. (Figure 2a–h)
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Cephalometric superimposition revealed that a vertical pattern of growth continued despite high pull headgear worn. There was little change in the anteroposterior plane. Effective reduction of the overbite has been achieved. The interincisal angle has reduced to 131 degrees and the lower incisor tip now lies ahead of the centroid of the upper incisor, a position believed to be favourable in the long term stability of corrected Class II division 2 incisor relationships (Houston, 1989; Figure 3). Although the upper incisor inclination has been corrected, the patient continues to have a high lower lip resting line and this may influence the incisor inclination in the future. The lower labial segment has been slightly advanced, but the pretreatment malocclusion suggested that the incisors may have been trapped by the palatal mucosa and the deep overbite. Posttreatment, the lower incisors now lie on the APo line. The lower intercanine width has been maintained at 27 mm. On completion of treatment, the patient exhibited good functional occlusion with canine guidance on right and left lateral excursions, and anterior guidance on protrusion. There was an absence of non-working side interferences.
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Case Report 2
A 14-year-old Caucasian female was referred by her General Dental Practitioner complaining of the appearance of the gaps between her front teeth. She presented with a Class I malocclusion on a skeletal I base with bimaxillary proclination. Both upper canines were ectopically positioned. The FMPA and lower anterior face height were within the normal range. Her lips were apart at rest with the upper incisors controlled by the lower lip. She had a full convex facial profile with an average nasolabial angle.
With the exception of the upper canines and third molars, all the permanent teeth had erupted. The patient had excellent oral hygiene and dental condition. The lower labial segment was proclined relative to the mandibular base and exhibited mild crowding. Both lower canines were mesially angulated. The upper labial segment was spaced with proclined incisors. Both upper and lower buccal segments were reasonably well aligned.
In occlusion, the incisor and buccal relationships were both Class I. There was good buccal segment interdigitation of the teeth. The overjet was measured to 3 mm and the overbite was average and complete to the palatal surfaces of the upper incisors. Both dental centre lines were coincident with the facial midline. Occlusal examination revealed group functional guidance on both sides with non-working side interferences between both right and left second permanent molars. No symptoms of mandibular dysfunction were reported, nor could any clinical signs be determined (Figure 4a–h).
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.
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). In this case, the upper lateral incisors appeared to be smaller relative to the remaining dentition and a Bolton tooth size analysis revealed that the maxillary labial segment was deficient by 2•5 mm. This can be cited as a aetiological factor. The bimaxillary proclination of the teeth was due to the soft tissue morphology. The need for orthodontic treatment as expressed by the Index of Treatment Need was grade 5i due to the impacted teeth. The pretreatment weighted PAR score was 23.
The aims of treatment were:
The treatment plan was as follows:
Analysis of space requirements demonstrated that there was sufficient space in the maxillary arch to accommodate both upper canines. In the lower arch, the mild degree of crowding was relieved by tooth reduction of 1 mm in total.
Following surgical exposure of both upper canines, the palatal surfaces were visible close to the maxillary midline. Active treatment required 26 visits over a 30-month period. A transpalatal arch was used in the first instance to maintain the intermolar width. This was modified in design, with two springs soldered to it which inserted into eyelet attachments bonded on to the palatal surfaces of the maxillary canines. With activation, the springs gradually encouraged the canines to move towards the line of the arch (Figure 5). Pre-adjusted Edgewise brackets (0•022 x 0•028-inch slot, Andrew's prescription) were bonded to the upper teeth. Following levelling and alignment using superelastic nickel titanium wire, elastomeric chain was used to consolidate the anterior segment spacing on a 0•020-inch stainless steel wire. At this stage, one of the palatal springs fractured and it was decided to remove both whilst recementing the palatal arch to maintain intermolar width. The canines were progressively brought towards the arch wire using elastomeric thread, the pull being directed to derotate both canines so that brackets could be bonded to their buccal surfaces. As the teeth moved closer to the line of the arch, a 0•014-inch superelastic nickel titanium wire was passed through all the bracket slots and fully ligated to the canine brackets in a ‘piggy-back’ fashion. A 0•018-inch stainless steel wire was then ligated over the superelastic wire. This proved to be a very effective means of applying a light, continuous force to the canines and bring them towards their final position. At this stage, lower molar bands were selected and bonded together with brackets.
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).
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). Parallel periapicals radiographs of both upper canines exhibited good alveolar bone levels. There was pocketing less than 3 mm adjacent to these teeth.
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Case 2 Assessment
Ericson and Kurol (1988) have suggested that if the crown of the canine has crossed the midline of the central incisor on a radiograph then the canine is in an unfavourable position with respect to bringing it into alignment. In this case, both canines were in unfavourble positions. Despite being informed of the risks, the patient opted to attempt alignment of both canines. The degree of lower arch crowding was very mild and therefore, as extractions were not considered to be necessary as part of the treatment plan, it was decided to proceed with exposure of the canines.
As the patient was happy with her facial appearance, reduction of the bimaxillary proclination was not considered. Indeed, any correction would have to be retained on a long-term basis as stability would be questionable due to the soft tissue aetiology.
The duration of active treatment was two-and-a-half years. However, buccal root torque was applied to both upper canines for 9 months of this time. Although post-treatment periapical radiographs of these teeth showed good alveolar bone levels, an opinion was sought from a Periodontist. No treatment was suggested for the 3-mm pocketing and a further review was arranged after 3 months. Care had been taken to use very light forces throughout treatment and fortunately, the patient maintained an excellent standard of oral hygiene throughout treatment despite the difficulty encountered due to the palatal positions of the canines and auxilliary attachments. Gingival recontouring on the upper right canine was suggested to improve aesthetics, but was declined by the patient. The canines will require long-term retention in view of the magnitude of movement that was required. However, the prognosis is favourable as both canines had good buccal root torque at the end of treatment.
The post-treatment cephalogram showed that both upper and lower incisors had maintained their pretreatment labio-lingual inclination. The lower intercanine width has been maintained at 26 mm. Cephalometric superimposition revealed a mainly vertical pattern of growth.
On completion of treatment, clinical examination revealed that the non-working side interferences had been eliminated between the second permanent molars, and that the patient had group functional guidance on both right and left lateral excursions.
The post-treatment PAR score of 1 demonstrates a 96 per cent reduction in weighted PAR score which lies in the ‘greatly improved’ category of the PAR nomogram.
Acknowledgments
I would like to express my thanks to all clinical supervisors at the Royal London Hospital, Whitechapel, for their excellent teaching and continual encouragement throughout my postgraduate training. In particular, special thanks should go to Mr Robert Lee, Mrs Margaret Collins, and Mr Robert Kirschen who supervised these cases.
References
Becker, A., Smith, P. and Behar, R. (1981) The incidence of anomalous lateral incisors in relation to palatally-displaced cuspids, Angle Orthodontist, 51, 24–29.[Medline]
Ericson, S. and Kurol, J. (1988) Early treatment of palatally erupting maxillary canines by extraction of the primary canines, European Journal of Orthodontics, 10, 283–295.
Houston, W. J. B. (1989) Incisor edge-centroid relationships and overbite depth, European Journal of Orthodontics, 11, 139–143.
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