Lingual Orthodontic treatment of periodontal cases with reduced bone level. 

Silvia Geron D.M.D., M.Sc, Moshe Davidovich D.D.S., M.M.Sc

www.lingualnews.com, Volume 1, Number 3 - July 2003

INTRODUCTION

Orthodontic patients with advanced periodontal disease (APD) are a special group with special treatment needs. Such patients often present with very high esthetic concerns, making them ideal candidates for lingual orthodontic treatment. This article briefly summarizes the anticipated problems in Lingual Orthodontic treatment of APD patients, and how to avoid and/or overcome these problems.

Essentially, the periodontal condition necessarily effects the treatment options of the adult lingual patient. Comprehensive treatment should routinely be restricted to adult slowly progressing periodontitis in order to simplify, shorten the treatment and avoid mechanical difficulties.

Special considerations have to be made in their orthodontic treatment in general (i.e. efficacy of treatment, adaptation of biomechanics, etc.), and specifically with Lingual appliances.

A. Case Selection

The first problem is identifying and adjusting patient's expectations. Patients seeking the reestablishment of esthetics with completely invisible orthodontic appliance may be disappointed to see the visible wires behind the large anterior spaces, at least at the beginning of treatment. They should also be made aware of the possibility of unesthetic outcomes such as long clinical crowns, or papilla-less gingival embrasures (i.e. "black triangles"). The latter which cannot be resolved due to gingival recession and marginal bone loss (Fig 1).

Fig 1: Case A: a. Flaring, numerous spaces, and gingival recessionin before treatment b. During alignment with upper lingual appliance, note the visibility of the wire behind the large anterior space. c. Black triangles and ong clinical crown at the end of space closure. d. Camouflage of anterior spaces by combination of orthodontics and restoration with composite materials.

B. Occlusal considerations
Occlusal relationships should be examined in centric occlusion for accurate evaluation of the overjet available for incisor retraction and anterior space closure. For example, case A (Fig 2) demonstrates a very small overjet in the initial dental photos due to an eccentric anterior slide. The numerous inter-dental spaces were eliminated without creating a negative overjet, because the mandible was repositioned during the improvement of posterior occlusion, thus eliminating the anterior slide.

Fig. 2: Case A, Before and after orthodontic treatment. The numerous inter-dental spaces were eliminated without creating negative overjet,  because the mandible was repositioned during the improvement of posterior occlusion, thus eliminating the anterior slide.

C. Aggravation of periodontal condition
The risk of exacerbation of the periodontal disease during orthodontic treatment. (1, 2,3) is a relatively greater risk in Lingual Orthodontic treatment because the lingual brackets are larger occluso-gingivally than labial brackets, and the clinical crowns are shorter on the lingual aspect than the labial. Therefore, retraction or palatal movement of the incisors tends to compress the gingiva against the brackets causing gingival swelling. (Fig 3) Therefore, it is extremely important to control the periodontal condition of lingual  patients before and during orthodontic treatment. (4)

Fig 3: Case B. Retraction or palatal movement of the incisors tends to compress the gingiva against the brackets causing gingival swelling.

D. Soft tissue considerations
A dentomuscular imbalance such as parafunction of the lip(s) (Fig 4) and/or tongue may also influence the pathogenesis of incisor flaring. The tongue crib effect of the lingual appliance is advantageous for this problem, especially if the patient is educated to position the tongue behind the brackets.

Fig 4: Case B. Parafunction of the lip(s) and/or tongue may alsoinfluence the pathogenesis of incisor flaring.

E. Intrusion forces
A universal problem in APD cases is the magnitude and direction of intrusive forces. In Lingual Orthodontics an intrusive force is applied to the incisors immediately after bonding the upper brackets due to the contact of the lower incisors on them which acts as an anterior bite plane (Fig 5), while the posterior teeth are disarticulated. (Fig 6) Intrusive force may improve periodontal cases with pathologic migration and extrusion of the incisors (5,6), However, the loss of attachment and alveolar bone support of the dentition due to the periodontal disease directly influences the biomechanics of any such treatment. intrusive forces are now applied labial to the center of resistance creating labial movement of the incisors and additional flaring. (Fig 7)
The occlusal loading force may be controlled by using posterior occlusal stops that reduce the initial contacts of the lower incisors on the upper bite plane. The height
the posterior occlusal stops has to be adjusted during the retraction and intrusion of the incisors. (Fig 8).

Fig 5: Case B. An intrusive force is applied to the incisorsdue to the contact of the lower incisors on the upper brackets bite plane.

Fig 6: The posterior teeth are disarticulated due to the anterior brackets bite plane

Fig 7: Intrusive forces applied labial to the center of resistance treating labial movement of the incisors and additional flaring

Fig 8 :Case B The occlusal loading force may be controlled by using posterior occlusal stopsthat reduce the initial contacts of the lower incisors on the upper bite plane

F.Anchorage control
One of the mechanical difficulties that should be considered in APD patients is anchorage control. (7) The quality of anchorage supplied by posterior teeth is decreased due to reduced bone level caused by periodontal disease. Reinforcement of anchorage should undertaken in treatment of these patients. This can be done by using hopeless teeth prior to their loss, impacted teeth, or implanting support anchorage (i.e. implants or onplants).

G. Incisor inclination
Under the best of circumstances it is a challenge to achieve ideal incisor inclinations during retraction using the Lingual Orthodontic technique. These teeth have a
tendency to retrocline when retracted. (8) With APD patients incisor inclination is even more difficult to control because of the change in the Center of Resistance due to apical migration of the level of alveolar bone support. This change necessitates an increase in the Moment-to-Force ratio of the applied biomechanical system in order to achieve translation. (9,10) (Fig 9)
Therefore, tipping movements must be avoided because they produce localized high stresses that increase the risk of tissue damage. Hence, a rectangular archwire
should be used in lingual orthodontic treatment of these patients from initial alignment, and when undertaking en mass sliding mechanics. Alternatively, control of incisor
inclination can be improved by using combination wires (AJ Wilcock, Victoria, Australia) or by using bidimensional brackets size (11). Mechanics with extrusive side effects (i.e. Class II elastics) should be avoided.
The aforementioned confounding mechanical and biological factors precludes that a conservative, nonextraction treatment plan for the lingual APD case be pursued. The treatment plan should be minimized and concentrated on achieving improved esthetics and occlusal goals to improve the prognosis of the compromised dentition.

CONCLUSIONS
Lingual orthodontic treatment of ADP patients requires additional considerations regarding case selection, treatment plan, aesthetics during and after orthodontic treatment, periodontal maintenance and mechanics of orthodontic treatment.

References:
1. Artun J, Urbye K. The effect of orthodontic treatment on periodontal bone support in patients with advanced loss of marginal periodontium. Am J Orthod Dentofacial Orthop 1988;93:143-8
2. Thilander B. Infrabony pockets and reduced alveolar bone height in relation to orthodontic therapy. Semin Orthod 1996;2:55-61
3. Polson A, Caton J, Polson AP, Nyman S, Novak J, Reed B. Periodontal response after tooth movement into infrabony defects. J Periodontol 1984;55:197-202.
4. Horwitz J., Lingual Orthodontics and Periodontal Treatment. www.lingualnews.com  Vol 1 No 2 March 2003
5. Melsen B. Tissue reaction following application of extrusive and intrusive forces to teeth in adult monkeys. Am J Orthod 1986;89:469-75
6. Melsen B, Agerbaek N, Eriksen J, Terp S. New attachment through periodontal treatment and orthodontic intrusion. Am J Orthod Dentofacial Orthop 1988;94:104-16
7. Diedrich PR : Orthodontic procedures improving periodontal prognosis. Dental Clinics of North America I Vol 40 No 4 ) 875-887 October 1996
8. Takemoto K. Anchorage control in lingual orthodontics. In: Romano R, editor. Lingual orthodontics. Hamilton, Canada: BC Decker; 1998. p.75-82.
9. Sitakowski RE :Lingual lever arm technique for enmasse translation in pateients with generalized marginal bone loss. J. Clin. Orth. XXXIII No12, Dec 1999
10. Sitakowski RE: optimal orthodontic space closure in adult patients. Dental Clinics of North America Vol 4o No 4 837-873 October 1996
11. Gianelly AA, Bednar JR, Dietz VS. A bidimensional edgewise technique. J Clin Orthod 1985;19:418-21

Fig 9:  Apical movement of the Center of Resistance
in APD patients due to apical migration of the level
of alveolar bone support. This necessitates an
increase in the Moment-to-Force ratio of the applied
biomechanical system in order to achieve translation

www.lingualnews.com 
Adult and Lingual Orthodontics
EDITORS:
Dr. Silvia Geron D.M.D., M.Sc
Dr. Rafi Romano D.M.D., M.Sc
Dr. Pablo Echarri D.M.D., M.Sc