Early tissue healing around unloaded orthodontic mini-screws. A study in the Beagle dog. Part I. Soft tissues.

• DOI: 10.22533/at.ed.4502322126

• Palavras-chave: -

• Keywords: Orthodontics; mini-implants; soft tissues healing; animal study.

• Abstract: The knowledge of tissue healing around orthodontic mini-screws can provide useful information for their clinical use. Even though there are some similarities with c.p. Titanium prosthodontics implants some differences exist in terms of materials, surface texture and load. The purpose of this study was to investigate the early phase of soft tissue healing around unloaded orthodontic mini-implants. In five Beagle dogs were inserted 20 self- tapping mini-screws. The animals were euthanatized at the day 0, 2, 7, 15 and 30. The bony specimens containing the screws were dissected, fixed, embedded in acrylic resin before they were cut. A novel orienting tool was developed to orient the cut exactly on the long axe of the screw. The samples were stained with Stevenel's blue and observed under light microscopy. Soft tissue adaptation to the neck of the mini-screw was excellent since from the beginning, forming a barrier against bacterial and foreign body penetration into the deeper tissue layers. A 2mm long junctional epithelium was observed at day 7. A connective tissue of about 1mm with predominantly parallel fiber orientation was also observed. A biologic width could be described with the features of the one around osseointegrated implants. No gap was observed between soft tissue and implant neck throughout the whole observation period. At day 30 the maturation of the soft tissue was complete and either epithelium or connective tissue was in intimate contact with the implant neck forming a valid barrier against bacterial and foreign body challenge.