COVER SCREW EXPOSURE OVER AN IMPLANT FIXTURE- AN OVERVIEW

The early exposure of a part of dental implant fixture through surrounding soft tissue might lead to a serious complication during the initial healing phase,

Early full or partial exposure of the cover screws can be considered a foci for plaque accumulation. If left untreated this may result in inflammation, damage to the peri- implant mucosa, and possible bone loss.( BARBOZA AND CAULA 2002).

COVER SCREW EXPOSURE MIGHT OCCUR DUE TO:

• Over-tightened sutures.
• Flap closure under tension.
• A decreased amount of keratinized tissue.
• Torn wound edges or a lacerated flap.
• Muscle pull along the wound edges.
• Oral habits like smoking and alcohol.

CLASSIFICATIONS:

TAL CLASSIFICATION( 1999):

CLASS O: Mucosa covering the implant is intact
CLASS 1: The cover screw can be detected by a periodontal probe
CLASS 2: Borders of perforation’s aperture do not reach or overlap borders of the cover screw at any point
CLASS 3: Cover screw is visible
CLASS 4: cover screw is completely visible

BARBOZA AND CAULA CLASSIFICATION (2002):

CLASS I: Cover screw spontaneous early partial exposure-a communication betwe3en the cover screw and oral cavity, with a fenestrated mucosa still partially covering the cover screw.
CLASS II: Cover screw spontaneous early total exposure-the fenestration reveals the cover screw completely.

Subdivisions are proposed based on clinical signs of healthy, inflammation, and suppuration. They are as follows:

Treatment Modality No.1: includes professional cleaning of cover screw if plaque or calculus is detected. The cover screw shold be mechanically cleaned using specific curettes, abrasive air, rubber cup, polishing paste, oral hygiene instructions reinforcement, and rinses with chlorhexidine digluconate 0.12%. Shortened recall periods for if inflammation signs are present. Radiographs are indicated to evaluate peri- implant bone morphology.

Treatment Modality No.2: includes identification of microorganisms and antibiotic therapy. In the presence of purulent exudates, specific microbial information is indispensable. Microbiological samples must be collected to identify the putative pathogens. If the patient presents localized peri-implant problem, a topical antibiotic therapy can be considered.

Treatment Modality No.3: includes surgical exposure of cover screw and adaptation of a healing abutment to avoid mucosa regrowth and facilitate patient oral hygiene.

Treatment Modality No.4: includes typical peri-implantitis treatment .

Conclusion :

Post operative soft tissue complications can be devastating to the implant’s overall success. Unfortunately, the factors that influence soft tissue healing are numerous. The potential threat of dehiscence is bacterial colonization that could occur between the implant surface and the oral environment. If left untreated, there could be damage to the peri- implant mucosa, and possible bone loss. Thus, it is important to detect these exposures early to avoid more serious complications.

References:

• BARBOZA,E. and A. CAULA. 2002 diagnosis, clinical classification, and proposed treatment of spontaneous early exposure of submerged implants. Implant dent,11, pp 331-337
• Bengazi, F.,J.L. Wennstrom, and u. lekholm. 1996. Recession of the soft tissue margin at oral implants. Clin oral iplant res, (7), pp. 303-310
• EL ASKARY, A.S., R.M. Meffert, and T. Griffin 1999a and b WHY DO IMPLANTS FAIL,PART 1 AND 2.
• Nemkovsky, C., and Z. ARTZI. 2002. Comparative study of buccal dehiscence defects in immediate,delayed and late maxillary implant placement with collagen membranes: clinical healing between placement and secont stage surgery, J Periodontol, 73, pp. 753-761
• Textbook on FUNDAMENTALS OF ESTHETIS IMPLANT DENTISTRY by EL ASKARY.