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 VariablesAge (yr) 53.9 ± 13.9 Gender (female) 339 (50.1)

Medically Related VariablesASA Status ( >II) 6 (0.9) Medically Compromised (Yes) 57 (8.5)Tobacco User (Yes) 57 (10.3)

Anatomic VariablesJaw

• 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 VariablesImplant Diameter

•3.0-3.5mm 195 (30.4)

•4.0-4.5mm 260 (40.6)

•5.0mm 168 (26.2)

•6.0mm 18 (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-stage 568 (84.0)

Abutment Related VariablesDiameter

• 3-4mm 118 (25.3)• 5.0-5.5mm 258 (55.2)• 6.0-6.5mm 91 (19.5)

Abutment Angulation•0° 435 (73.9)•15° 138 (23.4)•25° 16 (2.7)

Prosthetic Related VariablesFixed Prosthesis 632 (93.4)

OtherAntibiotic Use 574 (84.8)

Reconstructive Procedures 242 (35.8)

Implant Complications: Identification and Frequency

Prosthetic 2.7% (18/677)

Inflammatory10.2% (69/677) No

complications 86.1%

(583/677)

Operative 1.0% (7/677)

Overall Complication Rate: 13.9% (94/677)

Table 1: Factors Associated with Overall Implant Complications

Multivariate Cox ModelExposure Hazard Ratio 95% C I p-value

Tobacco Use 2.31 1.29, 4.16 0.0051(smoker vs. nonsmoker)

Reconstructive Procedure 1.18 1.03, 1.34 0.017(present vs. absent)

Implant Staging 2.56 1.45, 4.55 0.0013(one vs. two-stage)

Age (older vs. younger) 1.0 0.98,1.0 0.89Gender (female vs. male) 0.92 0.58,1.44 0.72Prosthetic Type 1.97 0.92,4.21 0.083

(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 3.26 1.74, 6.10 0.0002 (smoker vs. nonsmoker)

Reconstructive Procedure 1.17 1.001, 1.36 0.049 (present vs. absent)  

Implant Staging 3.03 1.64, 5.56 0.0004

(one- vs. two-stage)

Age (older vs. younger) 1.0 0.98,1.017 0.77 Gender (female vs. male) 0.94 0.56,1.57 0.82Jaw (maxilla vs. mandible) 0.64 0.36,1.15 0.13 

Table 3: Factors Associated with Operative Complications Multivariate Cox Model

Exposure Hazard Ratio 95% C I p-value Jaw 5.22 1.01, 27.03 0.048(maxilla vs. mandible)

Reconstructive Procedure 1.84 1.26, 2.68 0.002(present vs. absent)

Age (older vs. younger) 1.06 0.99,1.13 0.08

Gender (female vs. male) 0.40 0.069,1.96 0.24Restorative Dentist 0.41 0.14,1.17 0.10

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

AcknowledgementsFunding Sources: Department of Oral and Maxillofacial

Surgery Research Fund (MGH)Oral and Maxillofacial Surgery Foundation (VAV) NIH/NIDCR Dentist Scientist Award - K16 DE000275 (SKC)NIH/NIDCR Mid-career Investigators Award – K24 DE000448

(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: nancy_mcdermott@student.hms.harvard.edu