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The effect of diameter and length on the pullout strength of hydroxylapatite coated dental implants in the alveolar bone of dogs
M22 VanSickels, J.E., Flanary, CM.: Stability associated with mandibular advancement treated by rigid osseous fixation. J. Maxillofac. Surg. 43:338, 1985. Supportedin part by NIDR Research Grant DE 05215.
ABSTRACT SESSION VI ON IMPLANT RECONSTRUCTION SUNDAY, OCTOBER 2, lo:30 AM-~:~O PM MODERATOR: EUGENE E. KELLER, DDS, MS, ROCHESTER, MN REACTOR PANEL: ROBERT G. TRIPLETT, DDS, PhD, SAN ANTONIO, TX W. HOWARD DAVIS, DDS, BELLFLOWER,CA TheEffect of DiameterandLength on the Pullout Strength of Hydroxylapatite Coated DentalImplants ln the Alveolar Bone of Dogs. Michael S. Block, DMD, (Delgado, A., Fonrenot, M.G., Finger, I.M.) Louisiana State University School of Dentistry, 1100 Florida Ave., Dept. of OMS, New Orleans, LA 70119 Endosseous implant cylindrical implants are currently fabricated according to the specifications of the substrate metal, with the resultant size of the implant dependent on the strength of the structure of the implant. Clinically, the anatomy of the patient’s bone often limits the size of the implant. There are clinical situations whereupon a smaller implant is desirable when a small amount of bone is available. This study evaluates the pull-out strength of implants with different diameters and lengths, and compares the results with implants currently in use.‘,’ Six mongrel dogs were edentulated in the posterior mandible, leaving the canine and the third molar as vertical stops. After twelve weeks of healing, hydroxylapatite coated cylindrical implants were randomly placed into the mandible. Diameters (3.0, 3.3 and 4.0 mm) and lengths 4,8 and 15 mm) were varied such that 7 implants of each combination were evaluated. The dogs were placed on a soft diet, and sacrificed after 15 weeks. None of the implants were loaded. At the time of sacrifice, the mandibles were stripped of soft tissue, radiographs taken and the hemi-mandibles potted in acrylic in a universal jig, for pull-out testing on an MTS 810 using a universal joint on both plattens. The implants were pulled at a rate of 2 mm/min. The strength at which the implant was extracted from the bone was recorded and used for statistical evaluation. The extraction force for the implants was dependent more on length of the implant, rather than the diameter. The 15 mm long implants were extracted at 37.06 f 9.19 (4 mm diam.), 34.74 f 4.19 (3.3 mm diam.), and 33.39 f 7.93 (3.0 mm diam.) pounds, without statistically sign& cant differences. The 8 mm long implants extracted at 32.38 2 5.05 (4.0 mm diam.) 24.76 f 4.09 (3.3 mm diam.), and 23.76 + 11.05 (3.0 mm diam.) pounds, with the 3.3 vs. 4.0 mm diam. comparison significant (p < .05). The 4 mm implants extracted at 19.91 + 4.99 (4.0 mm diam.), 17.01 + 4.47 (3.3 mm diam.), and 13.69 + 0.66 (3.0 mm diam.) pounds. These pull-out forces reflect the shear interface of the bone-HA interface which was separated at the regions where the implant was in direct contact with cortical
bone. The longer implants which contacted the inferior border of the mandible pulled at significantly higher values, due to the HA-bone interface along two cortical bone interfaces. The longer and wider the implant, the greater the force needed to extract the implant from the bone. From this data, thinner implants of longer length may be clinically acceptable. References:
1. Block, M.S., Kent, J.N. and Kay, J.: J. Oral and Maxillofac Surgery, 45:601-607, 1987. 2. Cook, S.D. et al.: J. Dent. Res. Sp. Iss. 65:222, 1986.
FactorsAssociatedWith EarlyVerticalBoneL.osson EndosseousImplants.MichaelS. Block, DMD, (Kent, J.N., Provenzano, .I.) Louisiana State University School of Dentistry, 1100 Florida Ave., Dept. of OMS, New Orleans, LA 70119 As of 3/l/88, 462 hydroxylapatite coated implants (Integral, Calcitek, Inc.) have been exposed and restored.‘v2 At the time of exposure (10 to 12 weeks post-implantation), the amount of vertical bone loss was measured. Sixty-four implants were identified with two or more mm. of vertical bone loss. This report identifies the events associated with early vertical bone loss around implants. Thirty (46%) were associated with thin labial bone or dehiscence of the implant through the labial plate at the time of implant placement. Sixteen (25%) of these 64 implants were exposed on schedule but were not restored for greater than six months because of patient financial or institutional work load difficulties. Nine (14%) implants were malaligned and when restored resulted in significant on-axial forces placed upon them. Four (6.25%) implants had subperiosteal abscesses with drainage develop during the healing period (1,3,6 and 8 weeks post-implant placement). After appropriate incision and drainage, the infections resolved and at the time of exposure a 2 mm saucerization defect was present. Five (7.8%) implants became exposed to the oral cavity during the healing period with the healing screw clearly visible. 18 (28%) of these implants were located in the posterior mandible, 16 (25%) were located in the anterior mandible, 11 (17%) in the anterior maxilla, 9 (14%) in the posterior maxilla and 10 (15.6%) were in bone graft reconstructed (continuity defects) mandibles. All of these 64 implants had periodontal pockets that paralleled the amount of bone loss. Of the 64 implants, 58 had 2-3 mm of bone loss, 4 had 3-4 mm of bone loss and 2 had 4-6 mm of bone loss. In summary, factors leading to early bone loss around implants included thin bone or implant dehiscence at the time of placement, delays in restoration and the establishment of function on the implants, malalignment leading to non-axial stresses, infection and exposure to the oral cavity during the healing period. References:
1. Kent, J.N., et al., J. Dent. Res., Sp Iss. 66:1141, 1987. 2. Kent, J.N., et al., Biointegratedhydroxylapatite coated dental implants. Three year results and observations, submitted, JADA, 1988.
ABSTRACT SESSION VI ON IMPLANT RECONSTRUCTION SUNDAY, OCTOBER 2, lo:30 AM-~:~O PM MODERATOR: EUGENE E. KELLER, DDS, MS, ROCHESTER, MN REACTOR PANEL: ROBERT G. TRIPLETT, DDS, PhD, SAN ANTONIO, TX W. HOWARD DAVIS, DDS, BELLFLOWER,CA TheEffect of DiameterandLength on the Pullout Strength of Hydroxylapatite Coated DentalImplants ln the Alveolar Bone of Dogs. Michael S. Block, DMD, (Delgado, A., Fonrenot, M.G., Finger, I.M.) Louisiana State University School of Dentistry, 1100 Florida Ave., Dept. of OMS, New Orleans, LA 70119 Endosseous implant cylindrical implants are currently fabricated according to the specifications of the substrate metal, with the resultant size of the implant dependent on the strength of the structure of the implant. Clinically, the anatomy of the patient’s bone often limits the size of the implant. There are clinical situations whereupon a smaller implant is desirable when a small amount of bone is available. This study evaluates the pull-out strength of implants with different diameters and lengths, and compares the results with implants currently in use.‘,’ Six mongrel dogs were edentulated in the posterior mandible, leaving the canine and the third molar as vertical stops. After twelve weeks of healing, hydroxylapatite coated cylindrical implants were randomly placed into the mandible. Diameters (3.0, 3.3 and 4.0 mm) and lengths 4,8 and 15 mm) were varied such that 7 implants of each combination were evaluated. The dogs were placed on a soft diet, and sacrificed after 15 weeks. None of the implants were loaded. At the time of sacrifice, the mandibles were stripped of soft tissue, radiographs taken and the hemi-mandibles potted in acrylic in a universal jig, for pull-out testing on an MTS 810 using a universal joint on both plattens. The implants were pulled at a rate of 2 mm/min. The strength at which the implant was extracted from the bone was recorded and used for statistical evaluation. The extraction force for the implants was dependent more on length of the implant, rather than the diameter. The 15 mm long implants were extracted at 37.06 f 9.19 (4 mm diam.), 34.74 f 4.19 (3.3 mm diam.), and 33.39 f 7.93 (3.0 mm diam.) pounds, without statistically sign& cant differences. The 8 mm long implants extracted at 32.38 2 5.05 (4.0 mm diam.) 24.76 f 4.09 (3.3 mm diam.), and 23.76 + 11.05 (3.0 mm diam.) pounds, with the 3.3 vs. 4.0 mm diam. comparison significant (p < .05). The 4 mm implants extracted at 19.91 + 4.99 (4.0 mm diam.), 17.01 + 4.47 (3.3 mm diam.), and 13.69 + 0.66 (3.0 mm diam.) pounds. These pull-out forces reflect the shear interface of the bone-HA interface which was separated at the regions where the implant was in direct contact with cortical
bone. The longer implants which contacted the inferior border of the mandible pulled at significantly higher values, due to the HA-bone interface along two cortical bone interfaces. The longer and wider the implant, the greater the force needed to extract the implant from the bone. From this data, thinner implants of longer length may be clinically acceptable. References:
1. Block, M.S., Kent, J.N. and Kay, J.: J. Oral and Maxillofac Surgery, 45:601-607, 1987. 2. Cook, S.D. et al.: J. Dent. Res. Sp. Iss. 65:222, 1986.
FactorsAssociatedWith EarlyVerticalBoneL.osson EndosseousImplants.MichaelS. Block, DMD, (Kent, J.N., Provenzano, .I.) Louisiana State University School of Dentistry, 1100 Florida Ave., Dept. of OMS, New Orleans, LA 70119 As of 3/l/88, 462 hydroxylapatite coated implants (Integral, Calcitek, Inc.) have been exposed and restored.‘v2 At the time of exposure (10 to 12 weeks post-implantation), the amount of vertical bone loss was measured. Sixty-four implants were identified with two or more mm. of vertical bone loss. This report identifies the events associated with early vertical bone loss around implants. Thirty (46%) were associated with thin labial bone or dehiscence of the implant through the labial plate at the time of implant placement. Sixteen (25%) of these 64 implants were exposed on schedule but were not restored for greater than six months because of patient financial or institutional work load difficulties. Nine (14%) implants were malaligned and when restored resulted in significant on-axial forces placed upon them. Four (6.25%) implants had subperiosteal abscesses with drainage develop during the healing period (1,3,6 and 8 weeks post-implant placement). After appropriate incision and drainage, the infections resolved and at the time of exposure a 2 mm saucerization defect was present. Five (7.8%) implants became exposed to the oral cavity during the healing period with the healing screw clearly visible. 18 (28%) of these implants were located in the posterior mandible, 16 (25%) were located in the anterior mandible, 11 (17%) in the anterior maxilla, 9 (14%) in the posterior maxilla and 10 (15.6%) were in bone graft reconstructed (continuity defects) mandibles. All of these 64 implants had periodontal pockets that paralleled the amount of bone loss. Of the 64 implants, 58 had 2-3 mm of bone loss, 4 had 3-4 mm of bone loss and 2 had 4-6 mm of bone loss. In summary, factors leading to early bone loss around implants included thin bone or implant dehiscence at the time of placement, delays in restoration and the establishment of function on the implants, malalignment leading to non-axial stresses, infection and exposure to the oral cavity during the healing period. References:
1. Kent, J.N., et al., J. Dent. Res., Sp Iss. 66:1141, 1987. 2. Kent, J.N., et al., Biointegratedhydroxylapatite coated dental implants. Three year results and observations, submitted, JADA, 1988.