title: Experimental peri-implant tissue breakdown around hydroxyapatite-coated implants.
abstract: This study monitored experimental peri-implant tissue breakdown around hydroxyapatite (HA)-coated titanium dental implants. Thirty-two HA-coated cylindrical implants, in groups of two, were bilaterally inserted in the posterior maxilla and mandible in 4 Macaca mulatta monkeys. Two months after healing-abutment connection, a 2-month plaque control program was initiated. Clinical and radiographic recordings and peri-implant submucosal microbial samples were then obtained (baseline). Cotton ligatures were next placed around the healing-abutments and plaque control measures were abandoned. Clinical and radiographic recordings were repeated at 5 and 10 months post-baseline. Microbial samples were repeated at 10 months post-baseline, and ligatures were removed. Clinical, radiographic, and microbial examinations were again repeated at 11 months post-baseline. Mean modified plaque index (mPI; P < 0.01), gingival index (G]; P < 0.01), and bleeding on probing (BOP; P < 0.05) scores increased over the plaque accumulation period. The mPI, and GI scores decreased after ligature removal (P < 0.001). Mean probing depth (PD) and clinical attachment level (AL) increased between baseline and the 5- and 10-month examinations (delta PD 3.0 mm; delta AL 2.7 mm; P < 0.05). PD values were reduced following ligature removal (P < 0.05). AL values and BP scores remained unchanged. A significant negative correlation was found between induced defect depth and width of keratinized mucosa at baseline (P = 0.03). At baseline, the submucosal microbiota was dominated by coccoid cells. Following ligature placement, the microbiota included a large proportion of Gram-negative anaerobic rods, predominantly Porphyromonas gingivalis, Bacteroides forsythus, and Fusobacterium species as well as beta-hemolytic streptococci. Ligature removal had a limited effect on the composition of the submucosal microbiota. This non-human primate study indicates that ligature-enhanced plaque accumulation is a precursor of progressive peri-implant tissue breakdown around HA-coated implants. The associated microbiota resembles that of peri-implantitis and destructive periodontal disease in humans. This preclinical model may be useful to study modalities aimed at arresting peri-implant tissue breakdown and at regeneration of bone in peri-implantitis defects.
authors.affiliation: Center for Prosthodonotics and Implant Dentistry, Loma Linda University, CA, USA.
authors.forename: O
authors.initials: O
authors.lastname: Hanisch
authors.forename: C A
authors.initials: CA
authors.lastname: Cortella
authors.forename: M M
authors.initials: MM
authors.lastname: Boskovic
authors.forename: R A
authors.initials: RA
authors.lastname: James
authors.forename: J
authors.initials: J
authors.lastname: Slots
authors.forename: U M
authors.initials: UM
authors.lastname: Wikesjö
mesh_terms: D016301:Alveolar Bone Loss / Q000209:etiology* / Q000382:microbiology; D000818:Animals; D001421:Bacteria, Anaerobic / Q000302:isolation & purification; D015921:Dental Implants / Q000009:adverse effects* / Q000382:microbiology*; D003773:Dental Plaque / Q000150:complications / Q000382:microbiology; D003774:Dental Plaque Index; D004195:Disease Models, Animal; D017886:Durapatite; D005260:Female; D008026:Ligation; D008253:Macaca mulatta; D016348:Osseointegration; D010512:Periodontal Index; D010518:Periodontitis / Q000209:etiology* / Q000382:microbiology; D014025:Titanium
chemical_list: D015921:Dental Implants; D017886:Durapatite; D014025:Titanium