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Screw fixation compared to wire fixation for stabilizing sagittal osteotomies following mandibular advancement
M21 Ellis, E. and Carlson, D.S.: Stability two years after mandibular advancement surgery with and without suprahyoid myotomy: An experimental study. J Oral Maxillofac Surg 411426437, 1983
Stability of Simultaneous Maxillary Intrusion and Mandibular Advancement: A Comparison of Rigid and Non-Rigid Fixation Techniques. Larry J. Skoczylas, DDS, MS, (Ellis, E., Fonseca, R.J., Gallo, W.J.) University of Michigan School of Dentistry, 101 I N. University, Ann Arbor, MI 48109 All of the studies in the literature concerning the stability of bimaxillary surgery have used maxillomandibular fixation (MMF) techniques and have noted varying results. With the recent popularity of rigid internal fixation techniques for postsurgical stabilization of the mobilized jaws, it has become necessary for these studies to be repeated. The purpose of this investigation is to compare the stability of simultaneous maxillary intrusion and mandibular advancement using rigid and non-rigid fixation techniques. Only the first several weeks following surgery (the fixation period) were examined since this is the time when most relapse has been shown to occur. Lateral cephalograms of 30 individuals who underwent maxillary intrusion with concomitant mandibular advancement as the primary surgical procedures were obtained. Fifteen patients (14 female, 1 male) were treated with dental MMF supplemented with skeletal suspension wires for 8 weeks following surgery (Group MMF). Fifteen patients (10 female, 5 male) were treated with rigid internal fixation without MMF (Group RF). Concomitant advancement genioplasties were performed in 7 Group MMF and 13 Group RF individuals. Tracings of lateral cephalograms taken preop, immediately postop (within 48 hrs.), and prior to release of MMF in Group MMF individuals (8 wks.) or prior to splint removal in Group RF individuals (4 wks.) were digitized and analyzed by computer. Change within groups (surgical and postsurgical) was analyzed using the paired t-test. Change between groups was analyzed using Student’s t-test. The mean surgical changes included intrusion of the maxilla approximately 3 mm and advancement of the mandible approximately 5-8 mm. There was no significant difference between the two experimental groups in the magnitude or direction of surgical change other than slightly more advancement of the maxilla in Group RF (p < 0.01). Postsurgically, varying degrees of stability were noted in each group. On average, the maxilla of both groups continued to intrude (
References: Brammer, J., Finn, R., Bell, W.H., Sinn, D., Reisch, J. and Dana, K.: Stability after bimaxillary surgery to correct vertical maxillary excess and mandibular deficiency. J. Oral Surg. 38564-670, 1980. LaBanc, J.P., Turvey, T., Epker, B.N.: Results following simultaneous mobilization of the maxilla and mandible for the correction of dentofacial deformities: Analysis of 100 consecutive patients. Oral Surg Oral Med Oral Pathol. 54(6)X507-612, 1982.
Screw Fixation Compared to Wire Fixation for Stabilizing Sagittal Oste-otomies Following Mandibular Advancement. Ingeborg M. Watzke, MD, DDS (Turvey, T.A.) University of North Carolina, Dept. of OMS, CB#7450, Brauer Hall, Chapel Hill, NC 27599-7450 Seventy patients who underwent bilateral sagittal split osteotomy (BSSO) for mandibular advancement were selected for study. Thirty-five were stabilized with superior border wire and IMF (W), while the remaining 35 had screw fixation (S). Of the 70 patients, 50 were operated by 1 surgeon and the remaining by 5 different surgeons. All patients underwent pre- and post-surgical orthodontic treatment except 1 in the S Group. The patients were selected so the amount of mandibular advancement was similar in both groups (mean 4.5 mm in the S Group and 5.6 mm in the W Group) and all patients were followed for a minimum of one year. In all patients, immediate pre-surgery (Tl), immediate post-surgery (T2), splint removed (T3) and 1 year postsurgery (T4) cephalometric radiographs were digitized. X and y coordinates for 12 landmarks were studied at each time interval. Information was stored in a Microvax II and the SAS package was used for data management. Statistically significant differences between the groups were determined by a repeated measure analysis of variance. Time contrasts were performed with the significance level set at .Ol. Short term post-surgical change for each group was different. The W Group demonstrated skeletal relapse during IMF with mandibular anterior teeth coming forward, maxillary anterior teeth uprighting and gonion moving superior slightly. The S Group experienced continued anterior movement of all skeletal and dental landmarks. By 1 year post-surgery, the landmarks in both groups had moved similarly and the only statistically significant difference observed was at the gonial angle (p < .002) with the W Group experiencing greater anterior movement. Stability at B point and other skeletal or dental landmarks was not statistically different between the groups. This study indicates similar stability between wire and screw fixation groups at the 1 year post-surgery interval. Although screw fixation offers advantages that wire fixation does not, enhanced stability was not demonstrated in this study. References. Lake, S.L., McNeill, R.W., Little, R.M., West, R.A.: Surgical mandibular advancement: A cephalometric analysis of treatment response. Am. J. Orthod. 80:376-394, 1981. Turvey, T.A., Hall, D.J.: intraoral self-threading screw fixation for sag&al osteotomies: Early experiences. Int. J. Adult Orthod. and Orthog. Surg. 1:243-250. 1987.
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.
Stability of Simultaneous Maxillary Intrusion and Mandibular Advancement: A Comparison of Rigid and Non-Rigid Fixation Techniques. Larry J. Skoczylas, DDS, MS, (Ellis, E., Fonseca, R.J., Gallo, W.J.) University of Michigan School of Dentistry, 101 I N. University, Ann Arbor, MI 48109 All of the studies in the literature concerning the stability of bimaxillary surgery have used maxillomandibular fixation (MMF) techniques and have noted varying results. With the recent popularity of rigid internal fixation techniques for postsurgical stabilization of the mobilized jaws, it has become necessary for these studies to be repeated. The purpose of this investigation is to compare the stability of simultaneous maxillary intrusion and mandibular advancement using rigid and non-rigid fixation techniques. Only the first several weeks following surgery (the fixation period) were examined since this is the time when most relapse has been shown to occur. Lateral cephalograms of 30 individuals who underwent maxillary intrusion with concomitant mandibular advancement as the primary surgical procedures were obtained. Fifteen patients (14 female, 1 male) were treated with dental MMF supplemented with skeletal suspension wires for 8 weeks following surgery (Group MMF). Fifteen patients (10 female, 5 male) were treated with rigid internal fixation without MMF (Group RF). Concomitant advancement genioplasties were performed in 7 Group MMF and 13 Group RF individuals. Tracings of lateral cephalograms taken preop, immediately postop (within 48 hrs.), and prior to release of MMF in Group MMF individuals (8 wks.) or prior to splint removal in Group RF individuals (4 wks.) were digitized and analyzed by computer. Change within groups (surgical and postsurgical) was analyzed using the paired t-test. Change between groups was analyzed using Student’s t-test. The mean surgical changes included intrusion of the maxilla approximately 3 mm and advancement of the mandible approximately 5-8 mm. There was no significant difference between the two experimental groups in the magnitude or direction of surgical change other than slightly more advancement of the maxilla in Group RF (p < 0.01). Postsurgically, varying degrees of stability were noted in each group. On average, the maxilla of both groups continued to intrude (
References: Brammer, J., Finn, R., Bell, W.H., Sinn, D., Reisch, J. and Dana, K.: Stability after bimaxillary surgery to correct vertical maxillary excess and mandibular deficiency. J. Oral Surg. 38564-670, 1980. LaBanc, J.P., Turvey, T., Epker, B.N.: Results following simultaneous mobilization of the maxilla and mandible for the correction of dentofacial deformities: Analysis of 100 consecutive patients. Oral Surg Oral Med Oral Pathol. 54(6)X507-612, 1982.
Screw Fixation Compared to Wire Fixation for Stabilizing Sagittal Oste-otomies Following Mandibular Advancement. Ingeborg M. Watzke, MD, DDS (Turvey, T.A.) University of North Carolina, Dept. of OMS, CB#7450, Brauer Hall, Chapel Hill, NC 27599-7450 Seventy patients who underwent bilateral sagittal split osteotomy (BSSO) for mandibular advancement were selected for study. Thirty-five were stabilized with superior border wire and IMF (W), while the remaining 35 had screw fixation (S). Of the 70 patients, 50 were operated by 1 surgeon and the remaining by 5 different surgeons. All patients underwent pre- and post-surgical orthodontic treatment except 1 in the S Group. The patients were selected so the amount of mandibular advancement was similar in both groups (mean 4.5 mm in the S Group and 5.6 mm in the W Group) and all patients were followed for a minimum of one year. In all patients, immediate pre-surgery (Tl), immediate post-surgery (T2), splint removed (T3) and 1 year postsurgery (T4) cephalometric radiographs were digitized. X and y coordinates for 12 landmarks were studied at each time interval. Information was stored in a Microvax II and the SAS package was used for data management. Statistically significant differences between the groups were determined by a repeated measure analysis of variance. Time contrasts were performed with the significance level set at .Ol. Short term post-surgical change for each group was different. The W Group demonstrated skeletal relapse during IMF with mandibular anterior teeth coming forward, maxillary anterior teeth uprighting and gonion moving superior slightly. The S Group experienced continued anterior movement of all skeletal and dental landmarks. By 1 year post-surgery, the landmarks in both groups had moved similarly and the only statistically significant difference observed was at the gonial angle (p < .002) with the W Group experiencing greater anterior movement. Stability at B point and other skeletal or dental landmarks was not statistically different between the groups. This study indicates similar stability between wire and screw fixation groups at the 1 year post-surgery interval. Although screw fixation offers advantages that wire fixation does not, enhanced stability was not demonstrated in this study. References. Lake, S.L., McNeill, R.W., Little, R.M., West, R.A.: Surgical mandibular advancement: A cephalometric analysis of treatment response. Am. J. Orthod. 80:376-394, 1981. Turvey, T.A., Hall, D.J.: intraoral self-threading screw fixation for sag&al osteotomies: Early experiences. Int. J. Adult Orthod. and Orthog. Surg. 1:243-250. 1987.
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.