Harnessing Chronomodulation to Enhance Osteogenesis

Overview

Chronotherapy is an emerging field in biomedicine that leverages on fine-tuning the timing of drug delivery to obtain a therapeutic effect. Dr. Tamimi and his team have successfully harnessed chronotherapy using NSAIDs to enhance bone healing in a murine fracture model. Unpublished findings revealed that mice receiving carprofen for 3 days post-fracture exclusively during activity hours exhibited superior bone healing outcomes in comparison to specimens that received the same drug during resting hours. This is a 3-arm RCT aimed at evaluating the effect of different chronotherapeutic NSAID regimens on intraoral bone healing in humans using an extraction socket healing model in the context of an early implant placement protocol. The primary aim is to elucidate whether there are differences in osteogenesis and in the characteristics of the newly formed bone between patients following different post-operative NSAID chronotherapeutic protocols. Secondary endpoints of interest include assessment of alveolar bone and soft tissue dimensional changes between pre- and post-extraction, implant insertion torque, serum CRP levels, wound healing index and patient-reported discomfort at different time points. If proven beneficial, the proposed chronotherapeutic approach could be readily implemented in clinical practice as a standalone therapy or as a valuable complement to existing standard-of-care protocols, due to its simplicity, safety and cost-effectiveness.

Enrolled subjects will be randomly assigned to one of three groups (n=12 per group): Group A (Test) - Tooth extraction and intake of an NSAID (i.e. Ketoprofen ER 50 mg) at 8 AM and a non-NSAID (i.e. Acetaminophen / Paracetamol 500 mg) at 2 PM and 8 PM for a 3-day period, starting at 2 PM on the day of the extraction. Group B (Control 1) - Tooth extraction and intake of an NSAID (i.e. Ketoprofen ER 50 mg) at 8 PM and a non-NSAID (i.e. Acetaminophen / Paracetamol 500 mg) at 8 AM and 2 PM for a 3-day period, starting at 2 PM on the day of the extraction. Group C (Control 2) - Tooth extraction and intake of a non-NSAID (i.e. Acetaminophen / Paracetamol 500 mg) at 8AM, 2 PM and 8 PM for a 3-day period, starting at 2 PM on the day of the extraction. VISIT 1 - Screening Referred or self-referred subjects that appear to meet all the eligibility criteria upon phone pre-screening will be invited to an in-person screening visit at the UICOD. The study purpose, duration, potential risks and expected benefits will be explained in detail to the subjects, as part of the consenting process. All screened subjects will be provided with hard copies of the study timeline and the signed consent form. Upon medical and dental history review, as well as site-specific clinical and radiographic evaluation, eligible subjects interested in participating in the study will be scheduled for Visit 2. Intraoral photographs of the site of interest will be taken. Additionally, a cone-beam computed tomography (CBCT) scan will be obtained and interpreted to evaluate the study site, prior to the baseline intervention. VISIT 2 - Tooth Extraction (Baseline Intervention) Medical and dental history will be reviewed and updated, if necessary. Subsequently, subjects will be asked to sign the surgical procedure consent form. Prior to tooth extraction, an intraoral scan of the area of interest will be obtained using a digital scanner (e.g. Planmeca Emerald S). Likewise, a blood sample (\~ 4.5 cc) will be collected for serum C-reactive protein (CRP) analysis. Following administration of local infiltrative anesthesia, the study tooth will be extracted in a minimally traumatic fashion, avoiding flap reflection. Following tooth extraction, the socket walls will be carefully inspected for the existence of dehiscences or fenestrations. Sites presenting a bony defect affecting \>20% of the total wall height will be excluded. Site will be sealed using a collagen matrix (Mucograft Seal, Geistlich Pharma) stabilized with simple interrupted sutures. The intervention will be documented using intraoral photography. Upon completion of the intervention, subjects will be randomly assigned to one of the study groups and provided with detailed written and verbal post-operative instructions, including a drug diary specific to the group that they are allocated in and a visual analog scale (VAS) to record their perceived discomfort at day 0, 1, 2, 3 and 7 after the intervention. VISIT 3 - Postoperative Evaluation Any medical or dental history changes, or adverse events will be recorded. Sutures will be removed. An intraoral scan and photographs of the site will be obtained. Visual assessment of the healing status will be made using a wound healing index (WHI). Biofilm on the adjacent teeth will be removed and home care instructions will be revisited. VISIT 4 - Implant Placement At the beginning of this visit, a second segmental CBCT scan will be obtained, using the same settings employed at baseline. CBCT images will be employed to evaluate ridge dimensional changes compared to baseline, as well as bone availability for dental implant placement. Any medical or dental history changes, or adverse events will be recorded. A blood sample (\~ 4.5 cc) and an intraoral scan will be obtained. Assessment of the healing status will be made using the aforementioned WHI. After administering local infiltrative anesthesia, patients will undergo implant insertion, according to the early implant placement protocol.10 Following full-thickness flap elevation, a bone core biopsy of the study site will be obtained using a trephine drill of 2.5 mm in diameter or wider. The bone core will be immediately submerged in a solution of 10% neutral buffered formalin (NBF) for microCT (µCT) and histological analyses. Implant site preparation and placement will be conducted according to the manufacturer's recommendations (SLActive Bone Level - Straumann AG). Implant insertion torque will be recorded. Intraoral periapical radiographs will be obtained, as necessary, in order to assess implant placement location. Following final implant placement and cover screw delivery, simultaneous buccal contour augmentation will be performed via guided bone regeneration (GBR) using a dual bone graft. This graft composite will consist of an initial layer of locally harvested autogenous bone to cover the exposed implant surface, combined with a superficial layer of deproteinized bovine bone particles (DBBM; BioOss granules 0.25 - 1.0 mm, Geistlich Pharma), which will be subsequently covered with a native porcine collagen membrane (Bio-Gide; Geistlich Pharma). All procedures will be executed according to a two-stage (submerged) approach. Therefore, tension-free primary soft tissue closure will be attained. The procedure will be documented with intraoral photographs. All subjects will be provided with detailed written and verbal post-operative instructions. They will be instructed to avoid any disturbance in the surgical area for two weeks. Patients will be asked to use a mouthwash containing 0.12% of chlorhexidine gluconate twice a day, thirty seconds at a time, avoiding any eating or drinking for 30 minutes after rinsing, starting 48 hours after the baseline intervention. Post-operative medications (e.g. antibiotics, anti-inflammatory drugs and analgesics) will be prescribed on an individual basis. VISIT 5 - Postoperative Evaluation (Final Study Visit) This visit will be scheduled at approximately two weeks after implant placement. Any medical or dental history changes, or adverse events will be recorded. Intraoral photographs of the site of interest, will be obtained. Assessment of the healing status will be made using the aforementioned WHI. All remaining sutures will be removed. Biofilm on the adjacent teeth will be removed and home care instructions will be revisited. Upon completion of this final study visit, the patient will be entered in a regular patient care routine, including scheduling of a future visit for implant uncovering in no less than 4 months and later referral to the restorative dentist, in order to complete tooth replacement therapy.