Strontium-Hydroxyapatite Coated Mini-Screws: Antibacterial Effect and Stability

This randomized controlled clinical trial aims to evaluate the antibacterial efficacy and stability of strontium-incorporated hydroxyapatite (Sr-HA) coated orthodontic mini-screws (OMSs) used for maxillary canine retraction. A double-blind, split-mouth design was employed, involving 20 patients (aged 16-20 years), each receiving two titanium alloy mini-screws (1.6 mm × 8 mm): one coated with Sr-HA (5% concentration via electrochemical deposition) and one uncoated control. A total of 40 mini-screws were assessed. Following upper first premolar extractions, canine retraction was initiated using 150 g NiTi coil springs on 17×25 SS archwires. Mini-screws were placed between the upper second premolar and first molar without flap elevation or pilot hole drilling. Parameters including screw stability, antimicrobial activity, and gingival blood flow were monitored over a 4-month period. The incorporation of Sr-HA is hypothesized to enhance mini-screw osseointegration, reduce peri-implant inflammation, and improve clinical outcomes by leveraging the osteogenic and antibacterial properties of strontium. This study aims to provide evidence supporting the use of Sr-HA coatings to reduce mini-screw failure rates in orthodontic treatment.

Inclusion Criteria: 1. Adult patients within an age range (16-20) years. 2. Orthodontic treatment plan requiring the extraction of the upper first premolars. 3. Patients have fully permanent teeth are erupted (third molars are not included). 4. No previous orthodontic treatment 5. No medical problem that could interfere with treatment. Exclusion Criteria: 1. Presence of problematic healing such as, compromised immune defense, bleeding disorder, pathological bone quality, and xerostomia. 2. Inadequate oral hygiene. 3. Heavy smoking