Complications of Dental Implants: Identification, Frequency and Associated Risk Factors NE McDermott, BS*, S-K Chuang, DMD, MD*, VA Vehemente, BS*, S Daher, DMD†, A Muftu, DDS, MS††, TB Dodson, DMD, MPH*‡ Harvard School of Dental Medicine * Massachusetts General Hospital‡ Boston University Goldman School of Dental Medicine† Tufts University School of Dental Medicine††

Background and Significance Dental implants are a widely accepted treatment modality. Questions exist regarding complications associated with dental implants. Systematic reports of implant complications and associated risk factors are limited.

Specific Aims Specific Aim 1: To identify complications associated with dental implants. Specific Aim 2: To estimate the frequency of implant complications. Specific Aim 3: To identify risk factors associated with implant complications.

Hypothesis We hypothesize that we will identify risk factors associated with implant complications that may be modified by the clinician to enhance patient outcome.

Materials and Methods Study Design: Retrospective cohort Sample: Patients having > one Bicon ® implant placed at the Implant Dentistry Centre (IDC), Faulkner Hospital (Boston, MA) between 1992 and 2000 Randomly selected one implant per patient for study inclusion

Study Variables Predictor Variables (Risk Factors) Demographic - gender - age Medical - ASA status - tobacco use

Anatomic –implant location (maxilla vs. mandible, anterior vs. posterior) –bone quality (1-4) –implant proximity to teeth or implants Implant Specific –implant diameter and length –well size –implant coating –implant staging –abutment diameter and angulation

Prosthetic –removable (overdenture) or fixed (crown/ bridge) Reconstructive –use of procedures/materials to enhance recipient site Other -perioperative antibiotic use

Study Variables (Cont’d) Outcome Variable –presence or absence of complications Complications grouped into three categories –inflammatory –prosthetic –operative

Inflammatory Complications - mobility -pain -infectious process -peri-implantitis -impaired wound healing -gingival recession

Prosthetic Complications –abutment fracture/loosening –O-ring damage requiring replacement less than twelve months after insertion of overdenture –occlusal or prosthetic adjustment more than two weeks after delivery of permanent restoration –recementation of loose prosthesis within two weeks of delivery

Operative complications –inadvertent placement of implant into sinus or submandibular space –paresthesia

Data Analysis Descriptive statistics and complication frequencies Analyses to identify candidate variables (risk factors) associated with complications (p<0.15) -univariate Cox proportional hazards regression model Identification of specific variables associated with complications (p< 0.05) -multivariate Cox proportional hazards regression model

Descriptive Statistics Sample Size 677 Demographic Variables Age (yr) 53.9 ± 13.9 Gender (female) 339 (50.1) Medically Related Variables ASA Status ( >II) 6 (0.9) Medically Compromised (Yes) 57 (8.5) Tobacco User (Yes) 57 (10.3)

Anatomic Variables Jaw Maxilla 425 (62.8) Location Posterior 471 (69.6) Implant Proximity Between two natural teeth 259 (38.7) Between one tooth/one implant 182 (27.1) Other configurations 236 (34.2)

Anatomic Variables (cont’d) Bone Quality Type I 45 (0.7) Type II 126 (23.1) Type III 137 (25.1) Type IV 279 (51.1)

Implant Related Variables Implant Diameter mm 195 (30.4) mm 260 (40.6) 5.0mm 168 (26.2) 6.0mm18 (2.8) Implant Length 4-6mm 10 (1.6) 8mm 156 (24.3) 11mm 433 (67.5) 14mm 42 (6.6)

Implant Related Variables (cont’d) Coating Uncoated 115 (19.4) TPS 187 (31.5) HA 291 (49.1) Well Size 2.0mm 599 (88.7) 3.0mm 76 (11.3) Staging Two-stage568 (84.0)

Abutment Related Variables Diameter 3-4mm 118 (25.3) mm 258 (55.2) mm 91 (19.5) Abutment Angulation 0° 435 (73.9) 15° 138 (23.4) 25° 16 (2.7)

Prosthetic Related Variables Fixed Prosthesis632 (93.4) Other Antibiotic Use 574 (84.8) Reconstructive Procedures242 (35.8)

Implant Complications: Identification and Frequency Overall Complication Rate: 13.9% (94/677)

Table 1: Factors Associated with Overall Implant Complications Multivariate Cox Model Exposure Hazard Ratio 95% C I p-value Tobacco Use , (smoker vs. nonsmoker) Reconstructive Procedure , (present vs. absent) Implant Staging , (one vs. two-stage) Age (older vs. younger) , Gender (female vs. male ) , Prosthetic Type , (removable vs. fixed)

Breakdown of Inflammatory Complications 10.2% (69/677) frequency Gingival recession 0.4% (3/677) Impaired wound healing 0.7% (5/677) Peri-implantitis 1.0% (7/677) Infectious process 2.4% (16/677) Pain 1.6% (11/677) Mobility 4.0% (27/677)

Table 2: Factors Associated with Inflammatory Complications Multivariate Cox Model Exposure Hazard Ratio 95% C I p-value Tobacco Use , (smoker vs. nonsmoker) Reconstructive Procedure , (present vs. absent) Implant Staging , (one- vs. two-stage) Age (older vs. younger) , Gender (female vs. male) , Jaw ( maxilla vs. mandible ) ,

Table 3: Factors Associated with Operative Complications Multivariate Cox Model Exposure Hazard Ratio 95% C I p-value Jaw , (maxilla vs. mandible ) Reconstructive Procedure , ( present vs. absent ) Age (older vs. younger) , Gender (female vs. male) , Restorative Dentist ,

Table 4: Factors Associated with Prosthetic Complications Multivariate Cox Model No variables were found to be statistically related with prosthetic complications in the multivariate model (p< 0.05).

DISCUSSION Identification of implant complications –Inflammatory, Operative, and Prosthetic Frequency of implant complications –Overall: 13.9% (94/677) –Inflammatory: 10.2% (69/677) –Prosthetic: 2.7% (18/677) –Operative: 1.0% (7/677)

DISCUSSION (cont’d) Risk factors associated with implant complications –Overall : Smoking, one-stage implants, use of reconstructive procedures –Inflammatory : Smoking, one-stage implants, use of reconstructive procedures –Operative : Jaw (maxilla), use of reconstructive procedures –Prosthetic : None identified

Conclusion We hypothesized that we would identify risk factors associated with implant complications that may be modified by the clinician to enhance patient outcome. –Tobacco use –Implant staging

Future Investigations Tobacco Use -influence on implant complications Reconstructive Procedures - influence on implant complications

Acknowledgements Funding Sources: Department of Oral and Maxillofacial Surgery Research Fund (MGH) Oral and Maxillofacial Surgery Foundation (VAV) NIH/NIDCR Dentist Scientist Award - K16 DE (SKC) NIH/NIDCR Mid-career Investigators Award – K24 DE (TBD) We would like to acknowledge the clinicians and support staff of the Faulkner Hospital Dental Implant Center (Boston, MA) for their cooperation and unrestricted access to patient records. Inquiries: