The Rectangular Block Implant: A Pilot Study

The Rectangular block Implant (RBI) possesses state of the art technology and will be the first dental implant designed and manufactured in Australia. After thorough in vitro and in vivo analysis, it has been tailored for use in humans. The RBI represents a new concept in implant design and force distribution. The specific needs addressed by this novel dental implant are: 1. Maximal utilisation of the remaining bone volume; 2. Minimisation of risk to the Inferior Alveolar Nerve (IAN) or other vital structures in or near the oral cavity; 3. Maximisation of force distribution. This new implant is not designed to replace the plethora of dental implant designs that currently exist. It is aimed at providing a specialized implant fixture for individual clinical cases. The depth of the RBI will be 5.5mm, thereby qualifying it as a very short implant, i.e. suitable in cases of very low bone height. The aim of this project is to validate the restorative function of the Rectangular Block Implant (RBI) in the human jaw under conditions of low bone volume. The objectives will thus be to: I. Surgically place the RBIs into the jawbone of patients with resorbed alveolar ridges. II. Test the direct structural and functional connection between living bone. III. Test the biomechanical and functional load bearing of the RBI in the oral environment. 1. Methodology The exact placement of the RBI will be deliberated by a specialist team so that the prosthetic crowns attached to the implant will have adequate distribution of force and hence optimum functionality. A piezo-electric osteotomy shall be prepared which will require custom-made piezo-surgical instruments so that greater bone preservation and least soft tissue damage is incurred. 1.2 RBI Manufacturing The implant componentry which will include the RBIs, cover screws, abutments, abutment screws and stem handles shall be manufactured by Phantom Engineering Limited. This process involves lathe turning and surface preparation with titanium oxide and acid etching. The implant will be packaged and sterilized at the end of this phase, ready to be transported to the clinic. 1.3 Pre-Operative Phase A thorough clinical oral assessment will be performed followed by a Cone Beam Computerized Tomography (CBCT) to visualize the proposed surgical site in three dimensions. 1.4 Operative Phase Local anaesthesia will be administered via long hand block and local infiltration. An incision will be made and the osteotomy site will be prepared to receive the RBI in a manner that achieves primary stability, and encapsulates the entire implant. This will be achieved using surgical guides (prefabricated to accurately assist in placement of an implant in the bone structure) as per current implant placement protocols and a specialized piezo-electric ultrasonic surgical unit (Mectron Piezosurgery, Mectron Corporation, Australia). Consequently, a trial-fit (“dummy”) implant block will be used to gauge the size and orientation of the prepared site. Confirmation of attainment of adequate seating of the trial-fit block is a pre-requisite to proceeding with implant placement. The osteotomy site will be debrided with saline, and a sterile RBI transported with the use of an attached stem handle and seated into the site with firm finger pressure. The placement stem handle will be removed and the block implant tapped into position using the surface purchase points and the central screw shaft opening as per the trial-fit block. A cover screw will be placed. Soft tissue flaps will be placed over their original positions and sutures will be secured over the wounds to ensure adequate primary surgical wound closure. Antibiotics and analgesics will be prescribed post-operatively. 1.5 Post-operative Wound maintenance instructions will include a soft diet, prescription medications and oral hygiene instructions. After-hours telephone numbers will be provided. The patient will be dismissed after the achievement of haemostasis. The patient will be reviewed post-operatively after two weeks and suture removal will be performed. The patient will be asked to return for second stage surgery after a further 12 weeks. As per current implant protocols, the second stage of this treatment will again be under local anaesthesia. An initial surface incision will be made to expose the underlying cover screw, which will then be removed. 1.6 Assessment of Osseo-integration: Resonance Frequency Analysis Resonance Frequency Analysis is a painless and non-invasive technique. It will be performed from mesial, distal, buccal and lingual aspects, and repeated five times. A reading of 80 or greater will be indicative of successful osseointegration. Upon successful osseointegration, a trans-mucosal healing abutment, designed to facilitate the healing process around the gingiva surrounding the implant site, will be inserted to allow soft tissue healing. This process will not require suturing. 1.7 Prosthodontic Phase At three months post healing, impressions will be taken for the construction of the prosthetic crown. The prosthetic crown will be constructed in a laboratory: a process requiring approximately two to three weeks. The crown will then be screwed onto the abutment towards the end of this phase and checked for occlusal interferences and proper functional relationships. The patient will be instructed on proper oral hygiene maintenance generally and specifically regarding the new implant retained crown. 1.8 Follow Up and Long-Term Monitoring The function of the implant-abutment-crown complex will be monitored at regular intervals (monthly, then three-monthly then six-monthly and then yearly) over the following five years. Specific clinical parameters will be implant stability, component stability, functional capacity and peri-implant tissue health. The patient’s personal satisfaction (rating out of 10, and general comments) will also be recorded based on previously published protocols from this group. Successfully surviving implants will be left to function indefinitely, and a further prosthetic crowns may be needed for longer term (> 5 years) function. This is a prosthodontic painless process: it will be made using the master models made from the original impressions. 1.9 Participant Tasks For implant surgery to commence, the first visit will include a preoperative prosthodontic assessment. In the second visit, a cone beam computed tomography (CBCT) scan performed along with dental radiographs to visualise the quality and quantity of bone present at the receiving site of the RBI. In the third visit also, a presurgical assessment will be performed. In the fourth visit will last 60 minutes and the participants shall undergo the surgical placement of RBIs. Post-operative recovery will involve the use of analgesics, antibiotics and possibly time off work. A week later, in the fifth visit, dental radiographs will be taken and periodontal assessment of implant stability via clinical assessment and RFA will be done. In the sixth and the seventh visit RFA will be performed again and implant success and survival will be assessed. The sixth visit will be three months after the RBI placement and the seventh will be after six months. Each visit will take approximately 60 minutes. The eighth visit will be at the one-year mark. RFA and dental radiographs shall be performed on this visit. Therefore: a total of approximately eight hours of chairside time will be required for each participating patient in the first year of the pilot study. Throughout the course of this study, oral hygiene measures will be reinforced and reiterated at every visit. 2. Specific Details of Intervention The selection process of suitable patients and the consent process with the selected patients in the RBI Project will be undertaken by the A/Prof Roy Judge (Principal investigator, Head of Prosthodontics, Melbourne Dental School), Dr. Mohsin Nazir (Project Manager, PhD Student, Melbourne Dental School), and Dr. Ethemios Gazelakis (Project Supervisor, Honorary staff, Melbourne Dental School). • The preparation of implants to be used will be the responsibility of A/Prof Roy Judge, Dr. Mohsin Nazir, Dr. Ethemios Gazelakis and A/Prof Joseph Palamara. • The surgical pre-operative, operative and post-operative of the clinical trial will be performed by Dr. Ricky Kumar (Oral Maxillofacial Surgeon, Dental Health Services Victoria) and overseen by A/Prof Roy Judge, Dr. Mohsin Nazir, and Dr. Ethemios Gazelakis. • The prosthodontic or reconstructive oral management of patients will be the responsibility of A/Prof Roy Judge, Dr. Mohsin Nazir, and Dr. Ethemios Gazelakis. • The clinical data collection with respect to implant function, oral health and patient satisfaction will be overseen by A/Prof Roy Judge, Dr. Mohsin Nazir, and Dr. Ethemios Gazelakis. • The long-term monitoring of patients (over 12 months) will be the responsibility of A/Prof Roy Judge, Dr. Mohsin Nazir, and Dr. Ethemios Gazelakis. • The report drafting will be prepared by A/Prof Roy Judge, Dr. Mohsin Nazir, Dr. Ethemios Gazelakis, Dr. Ricky Kumar and A/Prof Joseph Palamara. • The general study design and the publication of results will involve A/Prof Roy Judge, Dr. Mohsin Nazir, Dr. Ethemios Gazelakis, Dr. Ricky Kumar and A/Prof Joseph Palamara. 3.0 Strategies for Monitoring Fidelity A/Prof Roy Judge will be in charge of the overall monitoring of fidelity within the study management plan. The file keeping, patient record keeping, and patient notes will be taken by Dr. Mohsin Nazir who will be in charge of managing the RBI project and reinforcing the agreed study protocol. Furthermore, the project manager will take notes, action to resolution, and report if adverse device events/serious adverse device events take place and the study protocol deserves abandonment. 4.0 The Information Brochure The information brochure contains an introduction to RBI therapy along with the purpose of conducting a clinical trial. It describes how the RBI is apt for case-sensitive functional treatment of the resorbed alveolar ridge. Moreover, procedural information and what is required of the participant during the course of this study is discussed in detail in this document. Daily oral hygiene practice is emphasized upon and the advantages, disadvantages and complications that may arise are described in plain language. Also, the inclusion and exclusion criteria of the RBI therapy is discussed together with secure data management and legal confidentiality. The participants are provided with contact information about the personnel who will be responsible for the interventional treatment.