implant DENTISTRY All-on-4 graftless approach: Not the panacea for all cases When considering restoring the edentulous arch, it is important to individualise treatment By Dr David B. Dunn, BDS (Hons), FRACDS, FPFA Treatment of the edentulous should be based upon a considered and detailed assessment of all the diagnostic variables, rather than ascribing to a formulaic approach based purely on the number of implants... Immediate implant placement and immediate function has revolutionised implant rehabilitation. The use of new implant designs, new surface technologies and biomechanical protocols has enabled the treatment of many patients, providing a predictable and simplified protocol. Most often, this avoids any grafting needs for the patient and offers the potential for immediate function and hence dramatically reduced treatment times, and at significantly reduced costs. This approach is manifested in P I Branemark s statement: A decisive factor in patient care is simplification of dental treatment, which should be based on identifying and utilising the enormous capacity of the existing anchoring tissues. When possible, one should avoid unnecessary advanced and complicated major grafting procedures. Hence, the last 5 to 10 years has seen a paradigm shift in treatment of the edentulous case and especially the atrophic maxilla, from a complex, multiple grafting, costly and extended treatment time methodology, to a simpler, graftless, costeffective and immediate load approach. According to the US bureau of statistics, there will be a prospected 10% decline in edentulism by 2020, which will be more than offset by a significant increase in the elderly, adult population. People reaching 65 will live an average of 17 additional years. 20% of all US American adults wear some type of removable denture. Thus, there will be a real and ongoing need for the treatment of the edentulous arch. However, as the methodology of All-on-4, as originally proposed by Malo, gains momentum and the dental marketplace sees this as a significant practice builder and commercially advantageous treatment modality, many practitioners are now jumping on the bandwagon, and there is a very real risk of lack of individual treatment planning, a recipe book approach in treatment, or worse still, a failure to follow the biomechanical protocols as originally proposed and presented by Malo. Importantly, not all cases are appropriate for an All-on-4 approach, despite the commercial push otherwise. Each and every case needs to be assessed on an individual basis. Notwithstanding the aesthetic considerations, such variables as bone quality and quantity; occlusal relationships; parafunction; vertical and horizontal cantilever dimensions; size and dimension of the occlusal prosthetic table; opposing arch considerations - be they implant supported, dentate or partially/fully edentulous; and the proposed prosthesis design and technology need to be assessed and an individual treatment plan established for each patient. Especially in the maxilla, this may 144 Australasian Dental Practice March/April 2013
Figure 1. The terminal dentition: Maxillary and mandibular All-on-4 graftless treatment approach with provisional immediate hybrid bridges in situ. require the use of more than four implants, and indeed in the treatment of the atrophic maxilla, may entail the use of zygomatic implants in combination with conventional anterior implants, or, in more extreme cases, the use of quad zygoma approaches. These types of advanced atrophic cases have historically been treated with a combination of sinus grafting and labial veneer/onlay bone grafts, with the donor site being the iliac crest. Understandably, many patients have been deterred by the surgical invasiveness, number of surgical appointments and extended treatment times, notwithstanding increased risk of implant failure and graft loss. The graftless solutions that are available today have hence revolutionised the approach to treatment, especially for the maxilla, and many patients who have understandably rejected treatment in the past are now viable and enthusiastic candidates. Contemporary implant and reconstructive treatment of the edentulous/failing dentition should be based upon a considered and detailed assessment of all the diagnostic variables, rather than ascribing to a didactic formulaic approach based purely on the number of implants. The present day All-on-4 approach is based upon two essential themes: reduced cost to the patient (single surgery, four implants, simple hybrid prosthesis) and immediate function (prosthesis connected to the implants on same day or within 2-3 days of implant placement). However, in certain circumstances, both these themes can be counter-productive or misleading in providing the patient with the most ideal aesthetic, functional and long-term implant rehabilitation. Firstly, with respect to the cost considerations, sadly many patients are being presented with a proposed definitive solution which entails the conversion of their existing denture to the definitive bridge or final reconstruction. This may March/April 2013 Australasian Dental Practice 145
Figure 2. Radiographic zones of bone volume availability relative to implant restorative options in the maxilla. enthuse the patient initially into accepting treatment; however, the reality exists that this type of tooth replacement will be subject to fractures and eventual failure in the short to medium term, with the patient being faced with the need for the construction of a new bridge. Further, subsequent healing changes will occur with bone remodelling and soft tissue healing resulting in spaces between the prosthesis and soft tissues that can lead to food impaction, speech difficulties or saliva escape, again requiring relining and repair of the bridge. Hence, there is a real issue of false economy and there needs to be an honest presentation and disclosure to the patient describing the need for an initial bridge to be utilised for some 3-6 months and then the construction of a definitive bridge following healing and bone/soft tissue remodelling. Alternatively, the discussions need to be had with the patient that a more robust, metal framework - immediate bridge can be constructed, but this will be subject to remodelling and repair, with a lifespan of approximately 5 years. Further, the patient needs to realise that there are limitations to the aesthetic and functional finessing that can be achieved with an immediate type of prosthesis construction, notwithstanding the materials science limitations of hybrid type prostheses currently utilised today. Secondly, in the enthusiastic drive to achieve immediate function, especially in the transition of the failing maxillary dentition in particular, there are often limitations and compromises made in the diagnostic work-up as well as significant limitations in the ability to accurately control the three-dimensional implant placement, in harmony with the desired and proposed future tooth positions. Sadly, this is commonly hidden by the use of acrylic flanges, over-contoured prostheses, or the use of judiciously placed composite restorations! In experienced hands and with an appropriate diagnostic work-up and a systematised approach, many of these issues can be overcome, however, for the newer practitioner embarking on this type of treatment, there are numerous pitfalls to be had with significant compromises in the end result. In certain cases, it is preferable to clear the residual dentition and undertake the appropriate alveolectomy and construct for the patient an immediate full denture for short-term use only. Following an appropriate healing time of some 4 to 5 months, new diagnostic procedures can then be undertaken utilising denture prosthetics to accurately define the ideal tooth position based upon aesthetics, function and speech. A radiographic template can then be constructed from this diagnostic work up and following the use of appropriate three-dimensional implant planning software, most ideally, guided surgery can then be undertaken utilising a flapless or mini-flap approach. This is most relevant for the maxilla. The negatives being increased costs for the patient, a longer treatment time and the need to utilize a short-term removable prosthesis. In terms of case selection, there are three basic patient types who are generally suitable for a graftless approach. The first group is the existing fully edentulous maxilla or mandible. In most cases there is sufficient bone volume for the placement of implants and a reduced arch (first molar to first molar) occlusion, utilising the Malo protocol with angled distal fixtures and reduced cantilevers. Alternatively, zygomatic implants can be used along with conventional anterior implants or a quad zygoma approach undertaken, as previously mentioned, if severely atrophic. The second group is the failing dentition, in either the maxilla or mandible, where the patient has been struggling, for one reason or another, and more often than not, has some residual teeth of questionable aesthetic and functional value, possibly in combination with the use of a removable partial prostheses. These types of patients are generally rapidly progressing to a fully edentulous state and wish to avoid full removable dentures in the near future. More commonly than not, they have avoided preventative and/ or restorative dentistry, with many being dental phobics. Perhaps their main motivators are to avoid a removable prosthesis. The third group are the patients generally in their watershed years with complex and extensive prosthodontic treatment which is now failing and requires replacement. This type of patient simply cannot afford, nor has the capacity to undertake extensive treatment that is required either on a time or cost basis, or alternatively, that the risk factors in their proposed reconstruction cannot justify the financial outlay. Furthermore, it may 146 Australasian Dental Practice March/April 2013
Figure 3. The dental phobic: Full mouth reconstruction with quad zygoma (plus two additional anterior implants) for the atrophic maxilla and conventional All-on-4 approach for mandible. Immediate provisional hybrid bridges. be their inability to maintain appropriate complex and difficult hygiene procedures that are required for the longer-term maintenance of their reconstruction. Many of these types of patients are attracted to the immediacy and cost-effectiveness of the All-on-4 /graftless treatment option, as they approach their later years. In the diagnosis and treatment planning for the All-on-4/graftless technique, there are certain key elements that need to be assessed. The first is the evaluation of bone quanity and quality. This is commonly obtained utilising 3D imaging technologies (CT/CBCT scanning). Ideally, a radiographic guide is worn by the patient during imaging and threedimensional implant planning software is utilised for subsequent assessment. For an All-on-4/graftless technique to be considered, the minimum alveolus dimension is 5 mm width and 10 mm in height for the maxilla and 5 mm width and 8 mm height for the mandible. Generally speaking, the issue is rarely with the quality of the bone and if it is, this can generally be overcome with appropriate surgical technique. The second issue is the restorative space considerations. There is a minimal need for 10 to 12 mm between the alveolus and the opposing occlusal plane if a direct to implant technique is utilised. If abutments are planned, a minimum of 12 to 14 mm is required; with 15 to 16 mm needed if a bar-retained prosthesis is to be utilized. The next important consideration is the alveolar ridge display during smiling. Further, the assessment needs to be made of the facial and lip support and how this relates to the proposed tooth position. If there is a significant lack of lip support, such as in an atrophic Class III ridge relationship, this will result in a significant horizontal cantilever and prosthetic profile from the implants to the prosthesis March/April 2013 Australasian Dental Practice 147
Figure 5. The terminal dentition/dental phobic: Full mouth reconstruction; immediate provisional 6-implant maxillary hybrid implant bridge and mandibular All-on-4 immediate hybrid implant bridge. 148 Australasian Dental Practice March/April 2013
implant DENTISTRY Figure 4. Definitive screw retained metal-ceramic fixed maxillary implant bridge to implant level. resulting in a horizontal shelf, or worse, a ridge-lap relationship, which will lead to hygiene difficulties, food impactions, etc. The assessment then needs to be made as to whether a fixed prosthesis is the appropriate treatment option, or, alternatively, the need for an alveolectomy, to provide a smooth transition from the implants to the prosthetic profile, as well as eliminating the display of the transition zone from prosthesis to soft tissues in the aesthetic display. The alveolectomy is relevant to both the maxilla and mandibular cases and importantly achieves four goals: 1. To eliminate the display of the transition zone from the prosthesis to the underlying soft tissues in speaking and smiling; 2. To eliminate the need for a ridge lap or flange and create a smooth transition from implant to prosthesis; 3. To even out the alveolar and soft tissue ridge contours to enable the placement of implants at the same level and provide a uniform seat for the pontic areas of the prosthesis; and 4. To provide appropriate dimension for abutments and the prosthetic construction. The graftless/all-on-4 approach can be undertaken utilising an open flap procedure with, or without a surgical guide, or, with guided surgery. Guided surgery is rarely utilised in this application for the mandible. Guided surgery with a surgical guide controlling the three-dimensional implant placement and generated from implant planning software, such as NobelClinician or Simplant, has several advantages. Highly accurate implant placement can be undertaken in harmony with the desired and planned prosthetic tooth position, which is especially relevant if more sophisticated future prostheses in ceramic are contemplated. Further, a very conservative flap design and reflection can be utilised such as with mini-flaps, which can considerably reduce post-operative swelling and discomfort as well as minimise the remodelling changes. Due to the accuracy of the guided surgery procedures and protocols, no window is required bilaterally into the sinuses to visualise the medial sinus wall anatomy, relevant to the placement of the angulated distal implants. Due to the inherent stability of the maxillary surgical guides due to the palatal vault anatomy as well as the use of multiple anchor pins, a simultaneous alveolectomy can be utilised with guided surgery, however, inherently, this requires the use of more aggressive incisions and flap reflection. A review of the scientific literature for both the maxilla and mandible indicates success rates equivalent to or better than conventional approaches in treatment utilised historically. The cumulative success rate at 4 to 5 years from eight publications, 14 centres, 470 patients and 1932 implants was 98.4% to 99.7%. Malo first published his protocol and initial results in the CIDRR in 2003, now 10 years ago. Full arch immediate loading success is based upon certain principles and the considerations of excellent initial bone anchorage i.e. primary stability, surface technologies and implant macro design to help facilitate high primary stability and stimulate early osseointegration and most importantly, cross-arch stabilisation and control of occlusal loading, especially with respect to cantilever dimensions. There are significant advantages to immediate loading of the edentulous patient as identified by Bedrossian in 2008. Significantly, the reduction in number of surgical procedures for the patient is reduced down to one appointment. There is improved comfort and greater patient acceptance, especially if it entails the avoidance of any removable appliance. The patient can have immediate function (though initially limited) and this dramatically decreases the treatment time and provides an immediate restoration of aesthetics, function and phonetics. Finally, there is a significant increase in success rates, comparative to conventional grafting type reconstructive procedures. In summary, there has been a significant paradigm shift in the treatment of the edentulous arch and indeed, the terminal dentition-type patient. The All-on-4/graftless approach has dramatically changed the playing field for both practitioner and patient alike. There is an increasing awareness in the community of these new approaches which can now offer patients a fixed implant reconstruction, generally with immediate function and only one surgical appointment. Furthermore, for the terminal dentition-type patient, they can avoid, in most cases, any denture experience at all and transition from their current situation to a fixed prosthesis within a few days. The successful and predictable outcome of this treatment approach however requires excellent diagnosis and teamwork and a close collaboration with experienced technical support. As in all aspects in dentistry, a thorough diagnosis needs to be undertaken and an individual and specific treatment prescription determined, relevant to the patient s needs, rather that a cookie cutter approach or mindless observance of a particular philosophy. About the author Dr David Dunn is the principal of the Macquarie Street Centre for Implant and Aesthetic Dentistry in Sydney, Australia. He lectures locally and internationally and along with courses for Nobel Biocare and Ivoclar Vivadent is part of the faculty for the gide Master Clinician Program in Implant Dentistry. He presents Mentor programs for a range of Aesthetic, Implant and Fixed prosthodontics subjects including the treatment of the edentulous arch utilizing a graftless approach. Should you be interested in receiving further information regarding upcoming programs or courses, please refer to our website or contact practicemanager@mscdental.com.au or call (02) 9247-1394. 150 Australasian Dental Practice March/April 2013