Change in Paradigm: Dental Implant Loading

Transcription

1 REVIEW ARTICLE IJOICR Change in Paradigm: Dental Implant Loading Change in Paradigm: Dental Implant Loading 1 Ramesh Chowdhary, 2 Nagalakshmi Chowdhary 1 Clinical Professor, Department of Prosthodontics, S Nijalingappa Institute of Dental Sciences, Gulbarga, Karnataka, India 2 Clinical Professor and Head, Department of Pedodontics and Preventive Dentistry, S Nijalingappa Institute of Dental Sciences Gulbarga, Karnataka, India Correspondence: Ramesh Chowdhary, Clinical Professor, Department of Prosthodontics, S Nijalingappa Institute of Dental Sciences, Gulbarga , Karnataka, India, drramc@yahoo.com Abstract Restoration with dental implants has proven to be a predictable modality for replacing, missing or failing teeth with various types of fixed or removable dental prostheses. Loading protocols for dental implants have been a central focus of discussion in the field since the origin of osseointegration. Several consensus conferences have been held on the topic, and recommendations have been published based on the evidence available at the time. This is a systematic review of change in treatment modality which has taken place from the delayed loading to immediate loading. The source of literature was Pubmed database. Keywords: Dental implant, Loading, Prosthesis. INTRODUCTION Restoration with dental implants has proven to be a predictable modality for replacing missing or failing teeth with various types of fixed or removable dental prostheses. Loading protocols for dental implants have been a central focus of discussion in the field since the origin of osseointegration. Several consensus conferences have been held on the topic, and recommendations have been published based on the evidence available at the time. 1 Clinical protocols for placing dental implants were originally developed by Branemark and coworkers. These investigators carried out an extensive number of studies to improve the success rates of osseointegration with dental implants. During the early stages of their research, one aspect, thoroughly investigated, was loading protocols. It was concluded that shorter healing times or premature loading resulted in nonintegration of the implants. The original Branemark protocol advocated implant installation to two stages. 2 It was dogmatically believed that after fixture installation, the implant had to be covered by mucosa to avoid epithelial down-growth between bone and implants and to minimize the risk for premature loading. In order to allow bone to integrate with the titanium-oxide layer covering the implant surface, it was postulated that an implant needed a extended healing time of 3 months in the mandible and 6 months in the maxilla. 3 Premature loading was taught to compromise the bone remodeling around the recently installed implant resulting in a fibrous encapsulation. Often, the patients were not allowed to wear removable dentures during the first weeks after surgery, to minimize the risk for overloading which could jeopardize osseointegration. In the second-stage of surgery, the implants were exposed and healing abutments were connected. The prosthodontic procedure was started, after another 6-8 weeks healing of the mucosal tissues. In clinical practice this meant a total treatment period of at least 5-6 months in the mandible and 8-9 months in the maxilla. These guidelines, however, were empirically based on clinical used experience rather than knowledge of biological principles. Many clinicians used these healing times in studies and, as such, 3 months in the mandible and 6 months in the maxilla become established as the conventional healing period. REVIEW AND DISCUSSION Two-stage to One-stage Surgery During the last decade, there has been a tendency to simplify the surgical and restorative procedure. Shortening the time frame between implant installation and functional loading has been an important evaluation in clinical practice, hence, lowering the barrier for the patient to go for an implant procedure. The first step has been to modify the surgical protocol from a two-stage to a one-stage procedure. After one-stage surgery, the implants are perforating the mucosal flaps and mounted with healing abutments that act as a International Journal of Oral Implantology and Clinical Research, September-December 2010;1(3):

2 Ramesh Chowdhary, Nagalakshmi Chowdhary healing scaffold for the mucosal tissues. Several investigators have proposed this nonsubmerged healing, yet with a mainly stress-free waiting time of 3 months. For this purpose investigators developed an implant specifically to be used for nonsubmerged healing. 4 After installation, the flaps are sutured around the polished neck portion of the implant avoiding the need for a second stage surgery. Their findings suggested that high success rates could be obtained with one-stage surgery. 5,6 Henry and Rosenberg 7 have described the successful use of onestage surgery in the mandible, yet with a 3 months waiting time before loading, in a group of completely edentulous patients. Ericson and coworkers 8 have demonstrated in a split-mouth study on 11 participants that turned surface Branemark implants installed in a one-stage procedure, albeit functionally unloaded during 3 months, performed identically as implants installed in two stage. Implant survival and boneto-implant adaptation were comparable in both treatment modalities, both initially and up to 5 years of laoding. 9 This was confirmed for mandibular implants installed for overdenture therapy in the anterior interforamina area 10 or in the premolar-molar areas of partially edentulous mandibles. 11,12 A large-scale follow-up study was conducted at the center periodontology Brussels from The one stage approach was retrospectively compared to the two-stage classical approach in completely and partially edentulous mandibular arches. In a cochrane review evaluating whether a one stage implant procedure is as effective as a two stage procedure or not it was concluded that the two procedures did not show clinical significant differences. 14 A one-stage procedure might be beneficial as it reduces the number of surgical interventions and the waiting time before providing the final restoration. However, in some clinical situations, for instance, when barriers for guided bone regeneration are used in conjunction with implants or when primary stability is not achieved. The two-stage approach might be the option of first choice. It can be concluded from the presented literature and the data that the classical two-stage surgical approach for standard implant installation has similar success rates as the one-stage approach without jeopardizing the clinical outcome. In the aforementioned studies, however, a 3 to 4 months healing period was respected during which the implants were a functionally loaded with no direct occlusion or articulation with the antagonistic teeth. During this healing period, temporary removable prostheses are often used to restore function and esthetics. This approach can sometimes lead to complications are even implant failure, especially attributed to overloading of single standing short (< 10 mm long) fixtures. Primary stability and lack of micromovements during the healing phase are considered to be two of the main prerequisites for successful osseointegretion of dental implants. 15 Hence, rigid provisional connection of the implants, in those cases, might be an option to reduce the risk for premature overloading. One-stage to Early Loading One of the fundamental factors for successful osseointegration is the stability of the implant during the healing phase such any motion at the bone-to-implant interface is kept below 150 microns, where implants seem to integrate with a predictable outcome. 16 Hence, the crucial factor is not the timing of loading but the capability to minimize movements of the implants during the healing phase. One of the main problems after one-stage surgery is the risk of a provisional removable prosthesis applying overload on the newly installed implants. Investigators have proposed to change the delayed loading protocols and started to rigidly splint implants shortly after implant installation. Early loading means that the implants are installed with a one-stage approach and functionally loaded within 2 months. 17 There is sufficient evidence for good clinical results with early loading on turned surface Branemark implants installed in the anterior mandible. Randow and coworkers 18 have treated 16 completely edentulous mandibles using a one-stage procedure and early loading within 3 weeks with a fixed rigid prosthetic reconstruction on 5-6 implants. In comparison with a control group of 11 patients treated with the conventional two-stage procedure and loading after 4 months, they reported similar results regarding implant success and marginal bone levels after months. No further complications occurred over a 5 years period of loading and bone resorption was found to be within the same range in both procedures. 19 Tawse-Smith 20 compared two early loaded with two conventionally loaded implants supporting an over denture in the edentulous mandible. There were no statistically significant differences for prosthesis failures. Implant failures and marginal bone levels are between the different loading groups. Malo and coworkers have recently shown 96% of implant survival in a study, whereby partial bridgework in the esthetical zone of both 142 JAYPEE

3 Change in Paradigm: Dental Implant Loading maxilla and mandible was functionally loaded with a provisional prosthesis shortly after implant surgery. The prostheses were free of occlusion and articulation for 5 months and then replaced by the final restoration. They reported a small number of complications, however, not differing in character from those normally encountered with conventional implant treatment. In a study of De Bruyn and Collaert, 21 a total of 184 turned surface titanium implants (Nobel Biocare Gothenburg Sweden) of various length (7-18 mm), width ( mm) or screw design (standard, MK II, MK III, MK IV) were inserted in completely edentulous mandibles. The diameter 3.75 mm implant was the first choice implant but in 15% of the sites wider 4 or 5 mm implants were needed to obtain optimal initial stability. An insertion torque value of 40 Ncm was considered a prerequisite for early loading. Implants were positioned predominantly between the mental foraminae and only 9 implants (5 patients) were positioned posterior to the mental foramen. Abutments of various types were connected immediately after implant installation and an impression was taken either immediately or within 1 week at the time of suture removal. The prosthodontic treatment was done by the referring dentists and finished on average 18 days after surgery. The majority of the prostheses were of the typical Branemark bridge design with 1.5 to 2 cm long cantilevers posterior to the most distally located implants. Opposing dentures, when present, were renewed or remounted. Implant stability was checked clinically after removal of the reconstruction after 12 and 24 months of loading. The prostheses were not removed routinely after this initial period. Periapical radiographs were taken with long-cone technique immediately after prosthesis connection and further yearly to assess bone to implant contact. Thirteen out of 184 (7.1%) implants failed within 3 months of loading in 5 out of 36 patients: 1 out of 153 implants (0.7%) failed in healed bone, and 12 out of 31 failed in fresh extraction sites. This consequently meant a loss of 3 out of 36 prostheses, all in the extraction group. The average marginal bone level measured initially and after 1, 2, and 3 years was 0.8 mm (SD = 0.5),1.0 mm (SD = 0.4), 1.1 mm (SD = 0.3), and 1.4 mm (SD = 0.5), respectively. This reflects a normal bone remodeling during function, a normal biological phenomenon related to healing of the peri-implant tissues after piercing the gingival tissues. It can be concluded that early loading of a fixed jaw anchored restoration on 4-6 turned surface Branemark implants in completely edentulous mandibular bone is a predictable treatment option in healed bone. This is in accordance with other studies using the same approach and the same implants 18 and comparable with the classical two-stage delayed treatment protocol. Immediate installation of turned surface implants after extraction and early loading yields more failures and seems to be unpredictable. 21,22 Early to Immediate Loading Immediate loading has been introduced as an innovative technique in the early 90s. In many cases, patients are not satisfied with a transition period of wearing a temporary removable prosthesis after implant surgery. Therefore, there was a growing interest in shortening the time frame between implant installation and functional loading of the prosthesis. It has now been acknowledged that early and immediate loading can provide similar results as the classical one or two stages delayed loading protocols, if certain criteria are fulfilled. Schnitman and coworkers 23 have published 10 years results of 28 one-stage immediately loaded implants and reported 4 out 28 failures compared to no failures with a two-stage surgery and loading after a healing period of 3 to 4 months. However, the last implants were only 10 mm long and supported extensive restorations. They concluded that more research was needed to obtain a good long-term prognosis for implants distal to the anterior region of the mandible. Several other prospective studies reported survival rates of % for immediately loaded implants when rigidly connected to restore completely edentulous mandibles. 7,24-34 Studies on immediate loading of implants in multiunit situations is the partially edentulous mandible 27,29,35-37 or maxilla. 27,29, 30,35-37 Implant survival rates ranged from 88.5 to 100% in the maxilla and from 91.3 to 100% in the mandible. Degidi and Piatellt 38 concluded that the survival rates dropped from 100 to 92.3% when the implants were loaded immediately after installation. This illustrates the importance of reducing micromovements at the bone-to- implant interface during healing of newly installed implants. When the occlusal load is too high on the provisional restoration (even when splinted to each other), the healing is disturbed resulting in a nonintegration of the implants. International Journal of Oral Implantology and Clinical Research, September-December 2010;1(3):

4 Ramesh Chowdhary, Nagalakshmi Chowdhary Other than less comfort for the patient, it includes a shortening of treatment time and a reduction in chair time and post-operative care. Immediate loading has a remarkably positive psychological impact. 39 It is possible to obtain a predictable outcome with the immediate degree of primary implant stability (high value of insertion torque seems to be one of the prerequisites for a successful immediate/early loading procedure. 22 Modification in implant design, the use of longer implants and altered surgical techniques can contribute to a better implant primary stability. For this purpose, it is advised to adapt the surgical preparation (underpreparing) of the implant bed according to the bone quality. However, care should be taken to avoid over-compression as this could result in additional bone resorption and even loss of integration. Changes in implant surface predominantly based on increased surface roughness and consequently leading to surface enlargement, increase the healing response at the bone-to-implant interface. This reduces the healing time before an implant becomes integrated and thus the risk for premature overloading. It is important to install the prosthesis as soon as possible after swelling which jeopardizes easy positioning of the implant bridge. The main problem in providing immediate loading is the time needed to process the prosthesis in the dental laboratory. Several authors have reported practical ways to cope with this problem. The Novum procedure (Nobel Biocare, Gotheborg, Sweden) introduced precisionfit surgical and prosthetic templates to guide 3 wide body implants loaded the same day with a hybrid prefabricated prosthesis. 40,41 Another clinical method to provide immediate loading is based on the pick-up techniques 42,43 described elsewhere as the Hong Kong bridge protocol. 24 In a denture conversion technique, temporary abutments are placed and a prefabricated prosthesis is adjusted to fit around the abutments by means of autopolymerising cold-curing resin. 44,45 CONCLUSION With the advancement in the research methodologies, implant dentistry has evolved in many aspects. Due to this many concepts have been changed or modified to reduce the time, cost etc and to benefit more to the patients. Implant loading is one such procedure which has enormously changed due the advancement in surgical producers, implant designs, surface changes from delayed loading to immediate loading. 144 REFERENCES 1. Albretsson T, Isider F. Consensus report session IV. London In: In Lang NP KT (Eds). Proceedings of the 1st European workshop on periodontology. London: Quintessence Publ., 1994; Branemark PI, Hansson BO, Adell R, Breine U, Lindstrom J, Hallen O, et al. Osseointegreion implants in the treatment of the edentulous jaw. Experience from a 10-year period. Scand J Plast Reconstr Surg Suppl 1977;16: Adell R, Lekholm U, Rockler B, Branemark PI. A 15-year study of osseointegrated implants in the treatment of the edentulous jaw. Int J Oral Surg 1981;10(6): Buser DA, Schroeder A, Sutter F, Lang NP. The new concept of ITI hollow cylinder and hollow-screw implants: Part 2. Clinical aspects, indications, and early clinical results. Int J Oral Maxillofac Implants1988;3(3): Buser D, Mericske-Stern R, Bernard JP, Behneke A, Behneke N, Hirt HP, et al. Long-term evaluation of non-submerged ITI implants. Part 1: 8-year life table analysis of a prospective multicenter study with 2359 implants. Clin Oral Implants Res 1997;8(3): Buser D, Weber HP, Lang NP. Tissue integration of nonsubmerged implants. 1-year results of a prospective study with 100 ITI hollow-cylinder and hollow-screw implants. Clin Oral Implants Res 1990;1(1): Henry P, Rosenberg I. Single-stage surgery for rehabilitation of the edentulous mandible: Preliminary results. Pract Periodontics Aesthet Dent 1994;6(9):15-22;quiz Ericsson I, Randow K, Glantz PO, Lindhe J, Nilner K. Clinical and radiographical features of submerged and nonsubmerged titanium implants. Clin Oral Implants Res 1994;5(3): Ericsson I, Randow K, Nilner K, Petersson A. Some clinical and radiographical features of submerged and non-submerged titanium implants. A 5-year follow-up study. Clin Oral Implants Res1997;8(5): Bernard JP, Belser UC, Martinet JP, Borgis SA. Osseointegration of Branemark fixtures using a single-step operating technique. A preliminary prospective one-year study in the edentulous mandible. Clin Oral Implants Res1995;6(2): Becker W, Becker BE, Israelson H, Lucchini JP, Handelsman M, Ammons W, et al. One-step surgical placement of Branemark implants: A prospective multicenter clinical study. Int J Oral Maxillofac Implants 1997;12(4): Collaert B, De Bruyn H. Comparison of Branemark fixture integration and short- term survival using one-stage or two-stage surgery in completely and partially edentulous mandibles. Clin Oral Implants Res 1998;9(2): Van de Velde T, De Bruyn H. Evplution from delayed to early loading on Branemark implants. Clinical implications and case reports. Aesthetic and Implant dentistry 2005;7: Esposito M, Grusovin MG, Martinis E, Coulthard P, Worthington HV. Interventions for replacing missing teeth: 1-stage implant placement (review).cochrane Database of Systematic Reviews 2007;CD Albrektsson T, Branemark PI, Hansson HA, Lindstrom J. Osseointegrated titanium implants. Requirements for ensuring a long-lasting, direct bone-to-implant anchorage in man. Acta Orthop Scand 1981;52(2): JAYPEE

5 Change in Paradigm: Dental Implant Loading 16. Cochran DL. The evidence for immediate loading of implants. J Evid Base Dent Pract 2006;6: Esposito M, Grusovin MG, Willings M, Coulthard P. Worthington HV. Interventions for replacing missing teeth: Different times for loading dental implants. Cochrane Database of systematic Reviews 2007;CD Randow K, Ericsson I, Nilner K, Petersson A, Glantz PO. Immediate functional loading of Branemark dental implants. An 18-month clinical follow-up study. Clin Oral Implants Res 1999;10(1): Ericsson I, Randow K, Nilner K, Peterson A. Early functional loading of Branemark dental implants: 5-year clinical follow-up study. Clin Implant Dent Relat Res 2000;2(2): Tawse-Smith A, Payne AG, Kumara R, Thomson WM. Early loading of unsplinted implants supporting mandibular overdentures using a one-stage operative procedure with two different implant systems: A 2-year report. Clin Implant Dent Relat Res 2002;4(1): De Bruyn H, Collaert B. Early loading of machined-surface Branemark implants in completely edentulous mandibles: Healed bone versus fresh extraction sites. Clin Implant Dent Relat Res 2002;4(3): Esposito M, Grusovin MG, Willings M, Coulthard P, Worthington HV. The effectiveness of immediate, early, and conventional loading of dental implants: A Cochrane systematic review of randomized controlled clinical trials. Int J Oral Maxillofac Implants. 2007; 22(6): Schnitman PA, Wohrle PS, Rubenstein JE, DaSilva JD, Wang NH. Ten-year results for Branemark implants immediately loaded with fixed prostheses at implant placement. Int J Oral Maxillofac Implants1997;12(4): Chow J, Hui E, Liu J, Li D, Wat P, Li W, et al. The Hong Kong Bridge Protocol. Immediate loading of mandibular Branemark fixtures using a fixed provisional prosthesis: Preliminary results. Clin Implant Dent Relat Res 2001;3(3): Colomina LE. Immediate loading of implant-fixed mandibular prostheses: A prospective 18-month follow-up clinical study preliminary report. Implant Dent 2001;10(1): Hatano N, Yamaguchi M, Suwa T, Watanabe K. A modified method of immediate loading using Branemark implants in edentulous mandibles. Odontology 2003;91(1): Nikellis I, Levi A, Nicolopoulos C. Immediate loading of 190 endosseous dental implants: A prospective observational study of 40 patient treatments with up to 2-year data. Int J Oral Maxillofac Implants 2004;19(1): Testori T, Meltzer A, Del Fabbro M, Zuffetti F, Troiano M, Francetti L, et al. Immediate occlusal loading of Osseotite implants in the lower edentulous jaw. A multicenter prospective study. Clin Oral Implants Res 2004;15(3): Degidi M, Piattelli A. 7-year follow-up of 93 immediately loaded titanium dental implants. J Oral Implantol 2005;31(1): Glauser R, Ruhstaller P, Windisch S, Zembic A, Gottlow J, et al. Immediate occlusal loading of Branemark system Tiunite implants placed predominantly in soft bone: 4-year results of a prospective clinical study.clin Implant Dent Relat Res 2005;7(Suppl 1):S Ibanez JC, Tahhan MJ, Zamar JA, Menendez AB, Juaneda AM, Zamar NJ, et al. Immediate occlusal loading of double acidetched surface titanium implants in 41 consecutive full-arch cases in the mandible and maxilla: 6 to 74-month results. J Periodontol 2005;76(11): Becktor JP, Isaksson S, Billstrom C. A prospective multicenter study using two different surgical approaches in the mandible with turned Branemark implants: Conventional loading using fixed prostheses. Clin Implant Dent Relat Res 2007;9(4): Van de Velde T, Collaert B, De Bruyn H. Immediate loading in the completely edentulous mandible: Technical procedure and clinical results up to 3 years of functional loading. Clin Oral Implants Res 2007;18(3): De Bruyn H, Van de Velde T, Collaert B. Immediate functional loading of TiOblast dental implants in full-arch edentulous mandibles: A 3-year prospective study. Clin Oral Implants Res 2008;19(7): Cannizzaro G, Leone M. Restoration of partially edentulous patients using dental implants with a microtextured surface: A prospective comparison of delayed and immediate full occlusal loading. Int J Oral Maxillofac Implants. 2003;18(4): Vanden Bogaerde L, Pedretti G, Dellacasa P, MazzatiM, Rangert B. Early function of splinted implants in maxillas and posterior mandibles using Branemark system machined-surface implants: An 18-month prospective clinical multicenter study. Clin Implant dent Relat Res 2003;5 Suppl 1: Ganeles J, Zollner A, Jackowski J, ten Bruggenkate C, Beagle J, Guerra F. Immediate and early loading of Straumann implants with a chemically modified surface (SLActive) in the posterior mandible and maxilla: 1-year results from a prospective multicenter study. Clin Oral Implants Res. 2008;19(11): Degidi M, Piattelli A. Immediate functional and non-functional loading of dental implants: A 2- to 60-month follow-up study of 646 titanium implants. J Periodontol 2003;74(2): Schropp L, Isidor F, Kostopoulos L, Wenzel A. Patient experience of, and satisfaction with, delayed-immediate vs. delayed singletooth implant placement. Clin Oral Implants Res 2004;15(4): Engstrand P, Grondahl K, Ohrnell LO, Nilsson P, Nannmark U, Branemark PI. Prospective follow-up study of 95 patients with edentulous mandibles treated according to the Branemark Novum concept. Clin Implant Dent Relat Res 2003;5(1): Henry PJ, van Steenberghe D, Blomback U, Polizzi G, Rosenberg R, Urgell JP, et al. Prospective multicenter study on immediate rehabilitation of edentulous lower jaws according to the Branemark Novum protocol. Clin Implant Dent Relat Res 2003;5(3): Castellon P, Block MS, Smith MB, Finger IM. Immediate loading of the edentulous mandible: Delivery of the final restoration or a provisional restoration which method to use? J Oral Maxillofac Surg 2004;62(9 Suppl 2): Gallucci GO, Bernard JP, Bertosa M, Belser UC. Immediate loading with fixed screw-retained provisional restorations in edentulous jaws: The pickup technique. Int J Oral Maxillofac Implants 2004; 19(4): Balshi TJ, Wolfinger GJ. Conversion prosthesis: A transitional fixed implant-supported prosthesis for an edentulous arch a technical note. Int J Oral Maxillofac Implants 1996; 11(1): Misch CM. Immediate loading of definitive implants in the edentulous mandible using a fixed provisional prosthesis: The denture conversion technique. J Oral Maxillofac Surg 2004; 62(9 Suppl 2): International Journal of Oral Implantology and Clinical Research, September-December 2010;1(3):