Orthodontic intrusion can be effective in adult patients with periodontal disease,1,2 as long as light, continuous forces are used and excellent oral hygiene is maintained.3,4 Such treatment can reduce infrabony defects and improve periodontal health,5-7 but requires a multi-disciplinary approach8,9 and a highly motivated patient.
Stable posterior anchorage can be difficult to achieve in patients with missing teeth.10 Although skeletal anchorage may be useful, the following case demonstrates intrusion of the upper incisors using only removable Invisalign appliances in an adult patient with periodontal disease.
Diagnosis and Treatment Planning
A 43-year-old female presented with extruded, protrusive, and labially inclined upper incisors and generalized anterior spacing (Fig. 1). A fixed prosthesis had replaced the upper right bicuspids and molars. Bleeding was evident on periodontal probing, and the patient had a flat upper labial frenum.
Invisalign treatment was planned for derotation and intrusion of the upper incisors and canines and uprighting of the upper right central incisor. The lower arch required slight intercanine expansion to allow the alignment and uprighting of the upper incisors.
The final ClinCheck provided 15 aligners for the upper arch and 10 for the lower (Fig. 2). The predicted duration of treatment was about eight months.
Scaling and root planing were performed before the start of orthodontic treatment, with the scaling repeated every eight weeks.
The first through 10th aligners were worn for 15 days each, except that a frenectomy was scheduled during the sixth aligner period to reshape the gingival marginal without traction from the upper frenum (Fig. 3). This aligner was worn for three weeks as the tissue healed.
The last five upper aligners were changed every three weeks, while the last lower aligner was being worn, to allow root movements. At the end of active treatment, the patient wore the last set of aligners for an additional four weeks. The entire Invisalign treatment lasted 11 months (Fig. 4). Fixed lingual retainers were then placed in both arches.
Invisalign appliances provided a viable alternative to conventional orthodontic intrusion in this patient, aligning the extruded incisors in a relatively short time with no need to remove the posterior prosthesis. The post-treatment radiographs clearly showed upper incisor intrusion and a reduction of the infrabony defect.
Moving the teeth at a rate of about .25mm per aligner, Invisalign applies a light, continuous force.11 Attachments are bonded to the teeth adjacent to the extruded teeth to provide a mechanical lock for the aligners and to allow pure sectional intrusion, using the same biomechanics as the segmented-arch technique. The aligner dissipates the reactive force over the entire posterior segment, which serves as the anchorage unit.
In contrast to fixed orthodontic appliances, the aligners can be removed for eating and brushing, allowing optimal daily hygiene.12 The comfortable, esthetic appliances have been enthusiastically accepted by patients. Chairtime for aligner replacement is minimal, and the clinician can compare the patient's results with the virtual ClinCheck images to immediately verify treatment progress.