The Effectiveness of Low-level Laser Therapy in Orthodontic Retention for Periodontal-compromised Patients

The Effectiveness of Low-level Laser Therapy as an Adjunct Strategy in Orthodontic Retention for Periodontal-compromised Patients

The aim of the study is to evaluate the effects of low-level laser therapy (LLLT) on patients with chronic periodontitis during a post-orthodontic period for 12 months. Following aspects will be assessed: 1. Effects on tooth stability maintenance and bone remodeling. 2. Effects on periodontal inflammation status. 3. Effects on cervical dentin sensitivity and quality of life. The study design is a randomised controlled trail. To eliminate any bias, the investigator will initially hypothesis there is no significant difference in the aforementioned aspects between teeth retained with an adjunctive LLLT strategy and those retained in a conventional regimen.

The study design is a randomised split-mouth design based on the result of investigator's pilot study. Thirty-five non-smoking Ethnic Chinese patients (male and female, age: 25-65 years) with chronic periodontitis will be recruited. The teeth in experimental group will receive LLLT during orthodontic retention period for 12 months, while the teeth in the control (placebo) group will not receive laser therapy. Orthodontic occlusal indices will be measured to explore LLLT's role in maintaining tooth stability. The effects of LLLT on periodontal inflammation status will be evaluated by assessing clinical periodontal parameters and the levels of supra-gingival and sub-gingival bacteria. The effects of LLLT on bone remodelling will be explored by testing the biochemical biomarkers in gingival crevicular fluid (GCF). Cone-beam computed tomography will also be used to provide clinical evidence of periodontal status and bone remodelling. Possible effects of LLLT on patient's quality of life will be investigated via validated questionnaires, subjective assessment of tooth sensitivity, and objective measurement of bite force.

Inclusion Criteria:

Thirty-five non-smoking Ethnic Chinese patients (male or female; age: 25-65 years) will be recruited from the Prince Philip Dental Hospital, Faculty of Dentistry, the University of Hong Kong into the following selection criteria:

1. Systemically health (with special regard to disease affecting tissue repair);
2. No medications required for periodontal therapy and no use of any antibiotic and/or anti-inflammatory medication in the preceding month;
3. Chronic periodontitis with at least two pairs (clinically matched) displaced single-rooted teeth (each pair of teeth is in the same arch but in two contralateral hemi-arches respectively belonging to the same tooth typology) having at least one site probing depth of 5 mm or more, interproximal attachment loss of 3 mm or more, and radiographic signs of alveolar bone loss before periodontal and orthodontic treatment.
4. Recent completion of orthodontic treatment and readiness for debonding and retainer delivery.

Exclusion Criteria:

1. smoking;
2. pregnancy;
3. under orthodontic treatment.