Marginal bone loss in dental implants: A literature review of risk factors and treatment strategies for prevention.

PURPOSE: Marginal bone loss (MBL) occurs in the periapical cervical bone after dental implant placement and abutment connection. MBL may not result in peri-implantitis; however, it is always accompanied by MBL. Recent studies have demonstrated that early MBL is a predictor of peri-implantitis. In this narrative review, we aimed to provide an evidence base for recommended treatment strategies for clinicians to prevent MBL. STUDY SELECTION: We reviewed the recent literature and performed a narrative synthesis of the evidence, focusing on available systematic reviews and meta-analyses of implant marginal bone resorption. RESULTS: The available evidence indicates that certain biological, material, and technical factors can influence MBL and consequently dictate the risk of developing peri-implant disease in later years. The order of the impact of the strength of each factor is unknown. Current recommendations to prevent MBL include controlling patients' smoking and hemoglobin A1c levels to sufficiently low levels before surgery and throughout their lifetime. Regarding the material, a platform-switching, conical-connecting implant system, and an abutment with a height of at least 2 mm should be selected. Placement should be performed using techniques that ensure sufficient soft tissue (keratinized gingival width > 2 mm, supracrestal tissue height > 3 mm), and non-undersized preparations in the cortical bone should be made with connected concave abutments during primary or secondary surgery. Patients should receive supportive peri-implant therapy during maintenance. CONCLUSIONS: MBL development is multifactorial and can be reduced by considering the biological, material, and technical factors.

Masseter muscle cross-sectional area and late implant failure: A case-control study.

INTRODUCTION: Occlusal overload is considered to be one of the causes of late implant failure. However, it is unclear whether the magnitude of the patient's occlusal force is a risk factor for late implant failure. PURPOSE: This case-control study aimed to clarify the association between the cross-sectional area (CSA) of the masseter muscle and late implant failure. METHODS: This case-control study was limited to implant-supported fixed prostheses. We compared cases with at least one late implant failure (n = 25 patients) to controls (n = 82 patients) without implant failure. Patients were matched by age, sex, year of surgery, jaw and tooth type, and bone graft. Log-rank and Cox proportional hazard regression analyses were used to identify possible risk factors for late implant failure. RESULTS: The incidence of late implant failure was significantly associated with masseter muscle CSA ≥504.5 mm2 (hazard ratio: 4.43; 95% CI: 1.82-10.79; p < 0.01). CONCLUSION: Higher masseter muscle CSA increases the risk of late implant failure.

Implant fracture failure rate and potential associated risk indicators: An up to 12-year retrospective study of implants in 5,124 patients.

OBJECTIVES: This study investigated fracture rates and risk indicators for fractures in internal connection dental implants. MATERIAL AND METHODS: We performed a retrospective analysis of 19,006 internal connection implants used in fixed restoration in 5,124 patients (4,570 males, 554 females) at the Dental Hospital of Veterans Health Service Medical Center between 2006 and 2015. Patients were followed through June 2018 (0.03-12.39 years post-installation). Clinical factors (age, sex, implant diameter, implant length, placement site, bone graft, fixture material, cervical feature, abutment connection, microthread, and platform switching) were recorded. Kaplan-Meier survival analysis identified risk indicators associated with an implant fracture. Cox regression models elucidated potential fracture risks. RESULTS: One hundred and seventy-four implants fractured in 135 patients, for an incidence rate of 0.92% after an average of 4.95 ± 2.14 years of use. Kaplan-Meier estimates showed that the 3-, 5-, and 10-year survival rates of implants were 99.8%, 99.2%, and 97.7%, respectively. In the multivariable Cox regression model, the diameter, location, history of bone graft, and microthread presence were significantly correlated with implant fractures. Wide-diameter implants had a reduced fracture risk within 90 months, after which the diameter did not correlate with fractures. Implants placed in the anterior mandible had a lower fracture risk within 90 months; mandibular premolar implants corresponded with a lower risk after 90 months. Implants without a history of bone graft or microthreads were more likely to fracture throughout the follow-up time. CONCLUSIONS: These results elucidate risk indicators for implant fractures and facilitate their reduction in clinical practice.

Dense cancellous bone as evidenced by a high HU value is predictive of late implant failure: a preliminary study.

OBJECTIVES: The mechanism of late implant failure is unclear. This study examined the association between sclerosing cancellous bone images and the risk of late implant failures using multi-detector row computed tomography (CT) imaging data. METHODS: We performed a case-control study. The study group consisted of consecutive patients with implant failures treated at Kyushu Dental University between 2001 and 2016. CT data for late failure of 36 implants in 16 patients were available. The study cohort consisted of 16 patients with 36 late failed implants and 28 patients with 113 successful implants. RESULTS: The mean survival rate was 6.9 months for early implant failure, 76.6 months for late failure with marginal bone resorption, inflammation symptoms, and so-called peri-implantitis, and 95.0 months for late failure caused by implant fracture. The mean HU value for cases in the control group was 507 compared with 1231 for cases with late failure implants. Logistic regression was used for analysis. There were signs of high radiodensity of peri-implant cancellous bone when comparing adjusted radiodensity per 100 HU using CT data (OR 2.35; 95% CI 1.73-3.20; p < 0.001). CONCLUSIONS: Within the limits of our study, the presence of high radiodensity and cancellous bone consolidation on imaging may be related to risk factors for late implant failure. Therefore, CT images of the host cancellous bone status for observation of visible sclerosis could be a useful diagnostic indicator for late implant failure.

Estudo retrospectivo da relação entre o tempo de carga protética e a perda tardia dos implantes / The relationship between prosthetic loading time period and late dental implant failure: a retrospective study

Este estudo retrospectivo teve como objetivo avaliar a relação entre a perda tardia dos implantes com o tempo de carga protética, realizados na Faculdade de Odontologia de Piracicaba durante o período de 11 anos. Para isso, foram selecionados 875 prontuários de pacientes submetidos a tratamento com implantes e prótese sobreimplantes durante um período de 11 anos, totalizando 939 implantes. Dos 55 implantes que foram perdidos após a reabilitação concluída e sob função, fez-se a análise do tempo entre a instalação da prótese e o momento do fracasso da reabilitação. A análise estatística utilizada foi a do teste t para amostras independentes (com o valor p < 0,05) e posterior modelo de regressão logística binomial, a fim de quantificar os resultados encontrados. Como resultado, foi observada influência estatisticamente significante entre a perda tardia dos implantes com o tempo da reabilitação em função (valor p = 0,000), apresentando risco de perda 0,7 vezes menor a cada mês (probabilidade = 0,7). Com este estudo, concluiu-se que a perda tardia dos implantes é maior nos primeiros meses da reabilitação e após o primeiro ano, a chance de fracasso diminui consideravelmente

This retrospective study evaluated the association between late implant failure and prosthetic loading moment at the Piracicaba Dental School for an 11-year period. For this, 875 charts of patients treated with implant-supported prostheses (n=939 implants) were selected. The Student´s t test for independent samples (p<0.05) and binomial logistic regression model (odds ratio) were used to analyze time between prosthesis function and failure. Fifty-five implants were lost in function. Statistically significant influences were observed between late implant loss over time in function (p = 0.000), with the risk being 0.7 times lesser each month. This study concluded that late implant failure is higher in the first months, and after the first year, the chance of failure is significantly reduced.