Use of Radiomics in the Evaluation of Bone Quality After Alveolar Ridge Preservation

In implant surgery, alveolar ridge preservation (ARP) techniques represent a useful approach to maintain, following tooth extraction, bone volumes in case of a scheduled implant placement. Multiple ARP techniques are described in literature, and they differ from reconstruction techniques, since the aim of these techniques is to preserve the residual socket, not to recreate one or more missing bony walls. Furthermore, their use is strongly recommended in sockets with a residual buccal bone wall with a thickness lower than 1 mm, as the post-extractive socket undergoes physiological bone remodeling that starts from the inner portion of the alveolus, due to the loss of the periodontal ligament that induces the resorption of the so-called bundle bone. One of the ARP techniques requires the use of a heterologous bone substitutes to fill the entire socket, and superficially covered by a collagen resorbable membrane to avoid graft dispersion.

Following preservation, it is mandatory the execution of a CBCT exam to evaluate bone volumes prior to implant placement. This radiographic exam permits to correctly plan the insertion of the implant and can also be suggestive for the definition of the bone quality, which represents a criterium for the choice of an adequate implant design. Often, the pre-operative evaluation of bone quality does not coincide with the intra-operatory one, and still the agreement on radiographic evaluation has proven to be different on intra and inter-examiner opinion analysis.

In this sense, radiomics could represent a useful support to the dental surgeon. Radiomics is a quantitative approach to medical imaging, able to create predictive models, basing on the research of the so-called radiomic features, which are intrinsic characteristics of the image. In medical field, radiomics has been used in oncology, but without any valid use. In dentistry, only few research has been made. Specifically, in an article radiomics has been suggested to evaluate marginal bone loss around implants, whereas another one suggests the use of radiomics to create a classification of bone density.

The aim of this project is to develop, through radiomics, a predictive model to evaluate bone regeneration following ARP techniques. The assessment of bone quality is performed through histomorphometric analysis, which is then related to radiographical images.

The enrolled patients must meet specific inclusion and exclusion criteria and, in order to obtain a statistical significance, a sample size of 60 cases has been purposed.

The clinical pathway for participating patients is fully aligned with standard clinical practice and consists of the following sequential phases:

• Screening and Recruitment: Patients are evaluated and recruited only if they meet all predefined inclusion criteria.
• Surgical Phase 1 (Baseline): Tooth extraction is performed immediately followed by simultaneous alveolar ridge preservation (ARP).
• Radiographic Assessment (6 Months): Six months after the preservation procedure, a Cone Beam Computed Tomography (CBCT) scan is performed to evaluate the regenerated bone volume.
• Surgical Phase 2 (6 Months): During the implant surgery, a small bone biopsy is harvested (using the bone tissue that is normally removed during standard osteotomy site preparation) followed by the simultaneous placement of the dental implant (Resista OneTime). ISQ values are registered.
• Prosthetic Phase (10 Months): Four months after implant placement (allowing for proper osseointegration), the final prosthetic phase is carried out to restore the tooth. ISQ values are registered.

Follow-up

• 1 month after loading
• 6 months after loading
• 12 months after loading

Histological analysis Histological and histomorphometric evaluations will be carried out by a single investigator. To preserve tissue orientation, bone cores will be retained inside the trephine drills and rinsed with a cold 5% glucose solution (278 mOsm/L) to clear blood traces under isotonic conditions.

Fixation will be performed using a 10% buffered formalin solution (pH 7.2) for 3 days, followed by dehydration through an ascending ethanol series. After a 5-day pre-infiltration step in a 50% resin/alcohol mixture, the biopsies will be extracted from the drills and fully infiltrated with methacrylate resin.

Following a 12-day polymerization process, samples will be sectioned longitudinally with a high-precision silicon carbide disc to a thickness of approximately 50 μm, then ground and polished under running water down to 30 ± 10 μm. Sections will be mounted on glass slides and stained with acid fuchsin, toluidine blue, and Von Kossa. Once all analyses are completed, samples will be transferred to licensed medical waste companies for disposal in compliance with current legal regulations.