Determinants of early failure of dental implants

Abughalia, Mohamed Alsharief Mohamed (2024). Determinants of early failure of dental implants. University of Birmingham. Ph.D.

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Abstract

In modern dentistry, the use of osseointegrated dental implants is widely accepted as a valid treatment that can provide reliable rehabilitation for fully or partially edentulous patients. Efforts are continuously being made in the field of implant dentistry to further improve treatment outcomes and reduce failures.
There is a growing interest in improving treatment planning for dental implants, starting with tooth extraction techniques, as every dental implant procedure essentially begins with tooth extraction. In this context, minimally invasive vertical tooth extraction systems have been developed to reduce bone loss after tooth extraction and facilitate subsequent implant restoration.
This PhD project started with investigating the Benex vertical tooth extraction system. We developed an in vitro animal model system to replicate the clinical procedure of vertical tooth extraction using the Benex system. Using this model, we measured the axial forces associated with the tooth removal process. Furthermore, we examined potential modifications in the Benex vertical extraction technique that may increase the success rate of tooth extraction and reduce maximal extraction force and associated untoward sequelae. However, due to the impact of the COVID-19 pandemic and the subsequent closure of the laboratories, we could not pursue lab work further as planned. Furthermore, these unforeseen circumstances have disrupted the original plans for conducting clinical trials to determine the effectiveness of vertical tooth extraction using the Benex system in reducing the need for flap surgery and post-extraction alveolar bone loss. Therefore, we have made necessary adjustments to the work plan and have developed an alternative PhD plan to investigate risk factors for early implant failure.
The main aim of this thesis was to assess risk factors associated with early implant failure. Identifying and assessing the potential risk factors for early implant failure can be of great importance in predicting treatment outcomes. Furthermore, surgeons can make informed decisions to improve implant therapy outcomes by recognising high-risk conditions and adjusting treatment plans accordingly.
To achieve our aim, we first conducted a systematic review and meta-analysis to identify risk factors for early implant failure reported in the literature. We also investigated the statistical methods used to adjust for confounders in these studies. We found that studies frequently reported univariate analyses only, or, where adjustments for covariates were made, the selection of these variables was typically not based on a robust causal structure, which prevents a causal interpretation of the results. Therefore, we constructed a causal model using Directed Acyclic Graphs (DAGs), incorporating variables potentially related to early implant failure and defining their causal relationship based on available literature, expert knowledge, and plausible assumptions. This was done to make the underlying assumptions regarding the causal structure explicit and to guide covariate selection for the statistical models.
To assess potential risk factors for early implant failure, we conducted a retrospective cohort study using data from the European Centres for Dental Implantology (ECDI) database. This study included 150,896 implants placed in 63,414 patients between 2010 and 2022. First, we performed a descriptive analysis of all variables to gain an overview of the dataset and identify its strengths and limitations. Then, we analysed the data by creating multilevel mixed-effects logistic regression models for each potential risk factor for early implant failure. The covariate adjustment sets used in these models were selected based on our previously proposed causal model. We found that certain factors have a causal association with early implant failure. These factors are male sex, cigarette smoking, immediate implant placement, low primary stability, using narrow and short implants, placing implants in upper molar and lower anterior sites, poor bone quality, insufficient alveolar bone height, bone augmentation, and transmucosal healing mode. We did not find an association of age and diabetes mellitus with early implant failure.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):