Congenitally Missing Upper Lateral Incisors treated by space closure: aiming for excellence

Ortho and Kids - Semi directs - Direct anteriors
11 Apr 2016

The prevalence of congenitally missing teeth has been studied and reported by many Authors: a presence ranging between 6 to 10% was found in the population, with a prevalence of congenitally missing upper lateral incisors (CMLI) between 1 and 2%. Furthermore, it has been found that agenesis of both maxillary lateral incisors is more common than the single one. Patients with congenitally missing maxillary lateral incisors (CMLI) often need challenging interdisciplinary treatment and the replacement of CMLI offers three treatment options: canine substitution, tooth-supported restorations, or single implants. The ideal treatment must fulfill individual esthetics, functional requirements and periodontal health: not only at the end of the treatment, but also in the long-term. The rationale, effectiveness and advantage for space closure treatment have been widely discussed in previous articles, and this treatment finds its greatest application since CMLI is usually diagnosed at young age. Space closure offers indeed the possibility of completing treatment before adolescence and achieving a long-term stable outcome at a young age. Hence, it is possible to avoid a long lasting period with temporary restorations waiting for the final restorative procedures at the end of growth. Long-term investigations on periodontal, functional and esthetic stability have shown that space closure can lead to an acceptable functional occlusion with no difference in prevalence of TMJ signs or symptoms and to a better periodontal condition with minor tendency to accumulate plaque and develop gingivitis when compared to prosthetic replacement. Moreover, in the last 15 years, gradual improvement in orthodontic finishing, supported by careful and minimally invasive restorative procedures, has led to high quality esthetic results, almost indistinguishable from natural dentition. The purpose of this article is to show the considerable improvement that can be nowadays achieved with the space-closure alternative by combining techniques from esthetic dentistry with carefully detailed orthodontic treatment. In order to obtain an ideal smile, a detailed orthodontic treatment is mandatory and thus includes:
– Extrusion of canine and intrusion of first premolar to reach optimal leveling of the gingival margins. This also allows not to have to grind the palatine cusp of first bicuspid during final build-up
– Root palatal torque of extruded canines in order to maintain proper thickness of the
periodontal labial plate and prevent the risk of recessions.
– Proper torque of intruded first premolars considering root anatomy to allow minimally invasive restorations.
Premolar intrusion and canine extrusion themselves can remodel the periodontal profile and properly locate the gingival margins, so that an optimal esthetic result can be achieved. This means the gingival margin of the new canine (i.e. the intruded first
premolar) is at the same level of the central incisor, while the gingival margin of the new lateral incisor (the extruded canine) is at a 2-3 mm lower level.
The intrusion of the first premolars was also performed in order to obtain a larger “canine” after the building-up of the generally short and small first premolars in the “normal” canine position.
About the difference in color between cuspid and bicuspid, cuspids are usually darker and/or more yellowish than the incisors, new home bleaching systems are available to achieve very good and stable results.
In order to explain how it is possible to achieve excellence in space closure, a case is shown step by step.

Fig. 1

Img. 1 – B.M., male aged 11y7m, comes at our observation in 2011 at the completion of permanent eruption, showing upper cuspid just in lateral incisors position.
The treatment plan was done, as well as the entire ortho treatment, by Dr. Marco Rosa, to provide the malocclusion correction, space closure and proper control of cuspid and bicuspid positions.

Fig. 2

Img. 2 – Occlusal view of the malocclusion

Fig. 3

Img. 3 – NiTi wires were used in first step of the alignment.

Fig. 4

Img. 4 – During gingival margin levelling and proper torque control of canines and first premolars, a cosmetic conturing of canine cusp and interproximal walls was made. As demonstrat­ed in 1970 by Tuverson, it is possible to recon­tour the cuspid to almost an ideal lateral incisor shape by grinding it with diamond instruments. Iatrogenic effects of grinding, such as increased sensitivity or pulp reactions, can be avoided by adequate and abundant water and air spray cooling, and prepara­tion of smooth and self-cleansing surfaces.

Fig. 5

Img. 5 – The grinding of the canine cusp can be performed during the orthodontic treatment but also at the end of the active treatment, immediately before restorative adjustments.

Fig. 6

Img. 6 – The debonding day could be called “the longest day”. In the same appointment, in fact, the patient will be debonded and the upper teeth will be restored.

Fig. 7

Img. 7 – After orthodontic space closure and debonding, a perfect plaque control is required, in order to obtain and maintain a good gingival profile.

Fig. 8

Img. 8 – When proper position of the “new laterals and the new canines” is achieved with the ortho treatment, no prep on the teeth surface will be necessary. Sandblasting under rubber dam will be performed, in order to clean the surface from biofilm and from residual orthodontic resins.

Fig. 9

Img. 9 Rubber dam view on the left side

Fig. 10

Img. 10 Rubber dam view on the right side

Fig. 11

Img. 11 – Using a caliber, different dimensions of upper right central and upper left central were detected. In order to achieve a proper tooth display, instead of direct restoration, a new protocol using prepolimerized composite shell was used. Four Componeer veneers, size L shade WO, were customized in shape and used for upper central incisors and bicuspid, and directly relined through preheated composite. After rubber dam isolation, each shell was luted one by one, starting from midline to upper first bicuspid, the “new” canine. Before luting the shell, it’s possible to improve esthetic results putting stains on the internal surface of the componeer. Perfect control in form, gingival margin and adaptation is thusly readily affordable. On the newly transformed canines (the “new lateral incisors”) only 2 direct restorations were made, in order to restore the mesial “black triangle”. To avoid color differences to show when compared at the interface with the cus­pid enamel, however, it’s possible to restore them using a brighter hue of dentin, followed by a home vital bleaching treatment.

Fig. 12

Img. 12 – A special focus must be paid in reshaping bicuspid in substitution of cuspid. The palatal cusp must not be cut as it functions as the cingulum of the new canine.

Fig. 13

Img. 13 – Final results immediately after rubber dam removing. Using fine diamond burs, disc, rubber points and diamond paste, macro- and micro-texture can be rendered on the componeer surface, hence obtaining secondary and tertiary anatomy features.

Fig. 14

Img. 14 – One week later, after the rehydration.

Fig. 15

Img. 15 – Smile display before orthodontic treatment and after composite restoration.

Fig. 16

Img. 16 – Occlusal view. The sulcus between buccal and palatal first premolar cusps was stuffed by the splint.

Fig. 17

Img. 17

Fig. 18

Img. 18 – Two-year follow-up