November 13, 2018
by Joshua Shieh, BDS, MDS (Perio, India)
Successfully treating patients with missing or non-restorable teeth with a fixed prosthesis can be one of the finest services rendered to dental patients. This art and science of replacing missing teeth or those with hopeless prognosis requires a thoughtful combination of many aspects of dentistry, including patient education, prevention of further dental disease, sound diagnosis, periodontal therapy, experienced surgical skills, occlusal considerations and post restorative maintenance. The path taken to achieving this fixed solution depends upon one’s sound knowledge of biological and mechanical principles, the growth of manipulative skills to implement the treatment plan, and the development of a critical eye for judgement and assessment in fine detail. 1
For the past 40 years, dental science and technology has constantly progressed and been able to allow patients to enjoy a higher quality of life by successfully restoring missing teeth with dental implants. In the early evolutionary phases, the titanium fixture had to be surgically placed and buried in bone, under soft tissue for a healing period of four to six months prior to any occlusal loading and final restoration.
Traditionally it would require two surgical appointments for fixture placement and exposure for the healing abutment prior to the initiation of impression making. 2 This protocol required that the implant be placed in adequate bone volume in ideal 3D prosthetically planned position. However, after most tooth extractions, studies have shown loss of over 40% of vertical height and 60% of alveolar width within the first six months. 3 This phenomenon is especially noticed in the anterior maxilla and labial resorption can cause significant aesthetic challenges during the restorative phase.
A new protocol was presented in 1976 by Schulte and Heimke 4, by placing dental implants into fresh extraction sockets offering the patient several advantages, including reduced surgical procedures, preservation of bone height, width and increased patient comfort. The success of this protocol is dependent on various contributing factors during treatment planning such as careful patient selection, defined bony socket walls, absence of active local purulent infections and operator experience. On the other hand, the morphology of the socket site, the absence of keratinized tissue, thin tissue biotype and lack of complete soft tissue closure over the extraction socket have been reported to adversely affect the success of implants placed immediately. 5
After a tooth is extracted (Table 1), during its healing phase various morphological changes occur to the hard and soft tissue. Studies show that implants placed immediately into fresh extraction sockets preserved as much vertical and horizontal bone. 6,7
Elian and colleagues in 2007 had classified these extraction sockets, based on the presence or absence of the buccal plate of bone. Clinical results of Type 1 post-extraction sockets with the implants in respect to buccal to palatal changes have been successfully documented. 8 To minimize the potential for buccal tissue collapse, the recommended protocol included grafting the “gap” present between the bony walls of an extraction socket and the body of the implant. In addition to the grafting, a custom-healing abutment or a full provisional, non-functionally loaded restoration was recommended. 9 Newer clinical procedures such as the socket shield technique, have been described to retain a part of the buccal coronal one third of the extracted tooth in an effort to maintain the coronal buccal bone plate, thereby preventing tissue collapse. 10
Further classification included those with the absence of the bony buccal plate with overlying soft tissues (Type 2 socket) and those with both missing buccal hard and soft tissues (Type 3 socket). In the presence of all bony walls, immediate implants for anterior and posterior sites are highly predictable. In sites where the buccal bony wall is absent, it would require additional grafting procedures such as the “ice cream cone technique”. 11
For successful guided bone regeneration, Murray in 1957 12 stated that there were three components necessary for the new growth of bone:
1) the presence of a blood clot,
2) pre-served osteoblast, and
3) contact with living tissue.
Melcher and Dreyer 13 investigated the importance of clot establishment and stabilization in GBR, and supported the role of the barrier as:
a) protection of the hematoma from invasion by non-osteogenic shields, and
b) stabilization of the hematoma and preventing its distortion.
The membrane used acts as a barrier preventing the invasion of fibroblasts from surrounding connective tissue. This creates a secluded space only for osteoblastic activity. This principle is referred to as the “osteopromotion”. The membrane barrier provides an isolated environment in which the osteogenic process of osteoconduction, osteoinduction, and osseointegration occur. The initiation of the prosthetic phase usually is around 12-16 weeks post implant placement.
A 65-year-old male patient had reported with a chief complaint of a broken tooth in the lower left molar region. The tooth had been root canal treated and a full crown done about 10 years ago. His crown had fractured about three years ago, patient was asymptomatic except for difficulty while chewing his food (Fig 1). The patient was medically fit (ASA–1) to undergo dental surgery.
Clinical Exam and Diagnosis
Reveals a root stump in 36 site (radiographic exam of the 36 site shows an endodontically treated root stump with no periapical / furcal pathology) (Fig. 2) missing 37 and 38, a 3 unit PFM bridge on the opposing 25-26-27 sites, generalized attrition, minor cervical abrasions and overall good oral hygiene.
Treatment options presented were:
1. No treatment
2. Endodontic re-treatment, surgical crown lengthening with bicuspidisation, two individual post/cores and a single piece crown
3. Extract 36, replace missing teeth (#36, #37) with a removable cast partial denture
4. Extract 36, socket graft, wait for 4-6 months, place implants in 36,37 (or only 36), wait 4-6 months and replace with screw retained restorations
5. Extract 36, immediate implant placement in 36 site and standard implant protocol for 37 site, wait 4-6 months and replace with screw retained restorations
After a detailed discussion of the risks, benefits, alternatives and costs, the patient decided to only replace 36 with option 5 (immediate implant protocol). The patient was fully informed and a written consent was obtained for the time of treatment, human cadaver source of bone grafting material, animal source of the collagen sponge and suture material.
The Treatment Plan
Included pre-surgical oral hygiene, premedications (Amoxicillin 500mg, 19 capsules, to take four capsules, one-hour prior to surgery and continue TID for five days, Ibuprofen 400mg, 16 capsules, to take one capsule, one-hour prior to surgery and continue TID for five days, Dexamethasone 4 mg, 7 tablets, to take two tablets, one-hour prior to surgery and continue BID for three days, Peridex mouth rinse, to rinse with 15ml for 30 seconds, BID for two weeks post-surgery), extraction of 36 (atraumatic protocols), immediate implant placement (5.0 mm dia or 6.0 dia and 10 mm length, internal hex 11o taper connection), allograft (cortico-cancellous), collagen sponge (bovine origin), a wide diameter healing abutment (6.0 or 7.0 dia and 5.0mm length), screw retained custom abutment with zirconia crown. The patient is to wear a night guard after the prosthetic phase.
The patient was advised to brush his teeth, scrap his tongue thoroughly and rinse for 30 seconds with a cup of 0.12% chlorhexidine gluconate (Fig. 3). Local anaesthesia with one carpule of 2% Lidocaine and 1:200,000 epinephrine given as inferior alveolar nerve block, lingual and long buccal for 36.
An osteotomy preparation at 1,500 rpm with cooled sterile saline irrigation using the lance drill at 10 mm depth was initially performed and enlarged with 2.2 mm twist drill at 11.5mm. A radiographic confirmation of the osteotomy was done with the 2.2 mm twist drill at full length verifying the planned final position of the implant (Fig. 4). Once the 3-dimensional position was verified clinically and radiographically, the osteotomy site was gradually enlarged to the final implant diameter and the furca was further split bucco-lingually using a surgical air-motor. Note the surgical split does not extend through the lingual cortex (to prevent any tissue trauma to lingual structures) (Fig. 5). No flap was elevated for this surgical procedure and the two individual roots were removed using periotomes and twist elevators (Figs. 6 & 7). A 5.0 x 10 mm internal taper connection implant was placed with over 35Ncm of primary stability. The cover screw was placed and the space surrounding the implant in the socket was grafted with 0.25 cc of cortico-cancellous powder. A collagen wound dressing was placed on the coronal portion and a 7.0 x 5.0mm healing abutment was hand torqued on removal of the cover screw. Simple interrupted sutures were placed mesial to the healing abutment with a 4-0 plain gut to prevent displacement of the collagen plug and a post surgical radiograph was taken (Figs 8. & 9). The post-surgical instructions were given and patient was reviewed in two weeks, six weeks and 12 weeks.
Healing was satisfactory with no post-surgical complications (Fig. 10). The healing abutment was removed, site irrigated with 0.12% CHX and the transfer impression coping was placed and hand torqued (Fig. 11). Radiographic verification of the impression coping was confirmed (Fig. 12). Upper arch alginate impressions, lower arch VPS impressions with a closed tray transfer technique and a putty bite registration was done (Fig. 13). Intra oral shade matching / mapping was done with Vita Classic shade tabs and necessary photographs were sent to the lab for customization (Fig. 14). After 14 days, a custom CAD-CAM fabricated titanium base with custom stained zirconia crown (Fig. 15) was inserted, verified intra-orally and radiographically–note the prominent platform shift (Fig. 16) and torqued as per manufacturer’s instructions of 30Ncm. Teflon tape was placed into the screw access hole and sealed with composite resin (Fig. 17). Occlusion was verified at maximum intercuspation and excursive movements with an 8 micron articulating foil. The patient was happy that he received a fixed functional and aesthetic restoration (Fig. 18) with minimal to no discomfort during the course of his treatment.
The subject of immediate dental implants requires meticulous treatment planning in both surgical and prosthetic positioning that are both physically executed at the same appointment. This concept must take into consideration skilled atraumatic surgical extractions, prosthetically driven 3D positioning of the implant, adequate osteotomy preparation to achieve primary stability, ability to graft the “gap” between the socket walls and implant body effectively, achieving primary closure without effecting tissue morbidity and above all, selecting the right patient and the right site for the procedure. This case report presented, highlights a few important clinical points that helped achieve close to ideal results. One of the pivotal factors for the success of any clinical procedure–is the selection of the right patient. Dr. Milus House14 in 1937 had described in detail about the types of patients receiving complete denture therapy. As clinicians we are all aware of the challenges in fabricating a complete denture and still satisfying the patient functionally and aesthetically. Similar to implant dentistry, for the case described, as per House classification, he was an ideal patient (philosophical) to accept and understand the treatment and its outcomes. Second factor is the site determined to receive an implant. Presence of adequate socket walls15, no active purulent discharge, no anatomic limitations (Inferior alveolar nerve canal, maxillary sinus floor). In this case, engaging the interseptal bone (flared roots) was important to achieving primary stability, other socket sites may not have adequate interseptal bone (tapered roots with less flaring) that requires longer implants to engage the peri-radicular bone. Certain sites like the maxillary second premolar (fused roots) may require the implant to be of a wider body diameter to engage the mesial and distal bony walls. Actively threading the buccal walls is not advisable as the trauma might cause buccal wall resorption in long term bone remodelling. It is important to remember the implant platform must be placed atleast 1 mm subcrestal to the buccal and lingual bony envelope to prevent thread exposure after remodelling. Other critical factors in immediate placement is the use of fixtures with active thread design and with proven surface treatments that makes the environment conducive for faster cell migration and osseointegration.
The aim of implant dentistry is to restore form, function and aesthetics for a patient who is dentally challenged. The primary modality of restoring a tooth with an implant to its efficient functional capacity requires a surgical intervention that most patients are apprehensive about. For a patient with a non-restorable tooth that needs extraction, healing time, surgery for implant fixture placement, more healing time and another minor surgery for the healing abutment does raise some concerns especially for the patient who is anxious about dental treatment. Immediate dental implants are predictable and beneficial for patients that remarkably reduces such surgical visits. When executed precisely, they can be an added invaluable remedy in tooth replacement that is practical, predictable and profitable. OH
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About the Author
Dr. Joshua Shieh BDS, MDS (Perio, India) is a third generation clinician from a family heritage of over 80 years of dentistry. A Fellow of the International Congress of Oral Implantology, a Pre-Fellow of the Academy of General Dentistry, Member of the American Academy of Cosmetic Dentistry, Member of the Economics Committee at the Ontario Dental Association, Clinical Instructor at the Oral Rehabilitation Unit, Dept of Periodontics, Faculty of Dentistry at the University of Toronto, Clinical Instructor at The Institute of Dental Excellence, Program Director and Founder of the Academy of International Dental Education. He currently practises as a general dentist in Mississauga, Ontario with special interests in hard and soft tissue regeneration. The author can be contacted by email: email@example.com.