Provisional Restorations in Implant Dentistry
Considerations for balancing esthetics and tissue healing in the maxillary anterior
Provisional restorations are an important and often challenging part of implant dentistry.1 Besides the fact that provisional restorations need to maintain an acceptable function and esthetic appearance until a permanent restoration can be placed, they serve as placeholders to prevent migration of neighboring teeth and extrusion of opposing teeth. They are also important for determining the best restorative design for the given scenario and providing a template for soft-tissue contouring and maturing.
The scenario chosen for this discussion focuses on provisional restorations in the maxillary anterior, where esthetic concerns are pre-eminent. In this area, provisionalization can be divided into three phases. The first phase involves provisional restorations immediately after tooth extraction and prior to implant placement; the second phase entails provisionalization after implant placement but prior to attaching a temporary restoration to an implant; and the third phase involves seating the actual implant-supported provisional restoration. The implant-supported provisional restoration ultimately is used to load the implant and is needed to develop optimal contours of the peri-implant mucosa prior to fabricating the final restoration.
Esthetically, provisional restorations after tooth extraction and prior to implant placement or during implant healing can be especially challenging. Combining the demands for an acceptable esthetic appearance with those of undisturbed tissue healing often requires a compromise agreed upon by patient and dentist. Several options for provisional restorations during the healing period after tooth extraction and/or implant placement are available. These include removable and fixed alternatives. While removable interim partial dentures are the go-to option in most cases, special attention must be given to their design in the areas of implant surgery. After implant placement—especially when combined with bone augmentation procedures—pressure may be applied inadvertently to the healing site. This pressure, defined as “transmucosal loading,” may be detrimental to bone graft healing and implant survival.1 It may also alter the surrounding soft-tissue contours unfavorably. Therefore, interim removable partial dentures must be designed carefully and checked for stability in function to avoid contact with and pressure to the underlying tissues (Figure 1).
As the healing progresses, the provisional partial denture teeth can be extended in their tissue-facing cervical area by adding acrylic resin for improved esthetics (Figure 2).
If tissue contact with the temporary partial denture teeth during the early healing phase is being avoided (eg, because of insufficient vertical space), an interim removable partial is not the appropriate choice. Alternatives are Essix retainers (Figure 3), resin-bonded fixed prostheses, or fixed “bridge” provisionals in cases with adjacent teeth that need to be crowned.
An overview of removable and fixed options with indications, advantages, and disadvantages is presented in Table 1 and Table 2.
Implant Loading Protocols
The esthetic zone represents an especially sensitive restorative region where multiple risk factors must be considered. Predictable esthetic outcomes rely on the selection of the appropriate treatment approach, especially the selection of the loading protocol. Multiple factors influence the predictability of a loading protocol (Table 3), including those that are patient, clinician, and biomaterial/procedure related. Patient-related factors include general health, intraoral condition (eg, periodontal status and history, parafunction, bruxism, occlusion), and the local condition of the implant site itself. Clinician-related factors include level of knowledge, clinical skills, and experience, all of which strongly influence patient selection, biomaterial choice, and treatment approach.2
Immediate Loading
The immediate provisional restoration (immediate loading) of an implant at the time of implant surgery has shown to be predictable in terms of achieving osseointegration.3 Hence, it is proposed as the approach of choice by many clinicians. The claim is that when placing an implant in an extraction socket, its immediate restoration represents the most predictable way of maintaining the pre-extraction soft-tissue contours. However, the existing literature clearly indicates that immediate placement and restoration is associated with a higher risk of complications, most notably labial mucosal recession due to the resorption of the underlying labial alveolar socket bone.4 Although implant survival data with the immediate approach are comparable to conventional loading times, actual treatment success that includes an assessment of esthetic outcomes and patient satisfaction3—is rarely reported in a comprehensive manner. Clinicians should therefore exercise caution when considering immediate loading of implants in the anterior maxilla, choosing this approach only when a case meets the following well-defined clinical conditions:
• No or minimal simultaneous bone augmentation is required in combination with implant placement.
• There is sufficient implant length (≥8 mm).
• There is excellent primary implant stability (≥35 Ncm insertion torque).
• There are no occlusal contacts on the provisional restoration.
• The implant is placed with an axis that allows a screw-retained provisional crown.
Excellent primary implant stability is an absolute requirement for immediately loading an implant with a provisional restoration. It is dependent on bone density and quality, implant design and surface, as well as the technique and accuracy of the osteotomy preparation.5 In addition, the clinician should be experienced with immediate-loading protocols.2 The literature has shown that keeping an immediate restoration out of occlusion increases the chance for implant survival by about 7% compared to immediate restorations placed into full occlusal contact and function.3 Screw retention is recommended for an immediate provisional, as it eliminates the need for cement, which can interfere with the healing process if it is not sufficiently removed.
Early and Conventional Loading
Early loading of dental implants (6 to 8 weeks after placement) has shown to be as predictable as conventional loading (3 to 6 months after placement) when assessing treatment success.6 Studies on the latest implant surface modifications have even demonstrated that sufficient osseointegration can be achieved in 3 weeks following implant placement, making the 3-week time-to-loading a predictable option.7 An exception would be if extended simultaneous bone augmentation is involved.2,3 In these cases, required healing times for the respective bone grafting material will dictate the time to loading.
Conventional loading after 3 to 6 months of healing continues to be the choice when the primary implant is considered inadequate for early or immediate loading, and if specific clinical conditions exist, such as a compromised host and/or implant site, the presence of parafunctions, or the need for extensive bone augmentation.2
Soft-Tissue Conditioning
An esthetic implant rehabilitation depends on both biologically and prosthodontically driven implant placement,8,9 a visually pleasing prosthesis,10 and an intact surrounding peri-implant mucosa.11 The peri-implant tissue architecture is the essence of implant esthetics,12 and the presence of a proportionally pleasing papilla is an important component.13 Patient perceptions of the presence of interdental papillae are subjective and dependent upon individual interpretation,14 although the lack of a papilla—resulting in an open embrasure—can negatively affect the patient’s smile. Kokich and colleagues showed that the acceptable threshold for an open gingival embrasure, defined as the space from the tip of the interdental papilla to the interproximal contact point, was 3 mm when assessed by general dentists and lay people.15
Depending on the extent of soft- and hard-tissue loss and the patient’s lip line, it is important to evaluate whether pink porcelain needs to be incorporated into the final restoration to simulate the surrounding peri-implant mucosa during the treatment-planning phase. For restorations involving two or more adjacent teeth, soft-tissue conditioning via provisional prostheses may not be necessary if pink porcelain will be used for the final restoration design.16
The form of an endosseous implant differs from a natural tooth root in various ways. This is of primary significance in the transmucosal region. Natural anterior teeth have a triangular shape when viewed in a cross-section at the mucosa level. In contrast, the cross-section of an implant is round. To create the illusion that an implant restoration is emerging through the surrounding mucosa like a natural tooth crown, the mucosa must be shaped and matured in that manner. This can be done with the help of a customized healing abutment or, preferably, with the provisional restoration. Therefore, an impression including the implants is obtained using implant-specific impression posts (Figure 4).
Laboratory-processed, screw-retained provisional restorations are the authors’ treatment modality of choice. In the resulting master cast, which contains the implant analog(s), a wax-up is performed and indexed. Subsequently, the peri-implant areas in the stone cast are carved according to the desirable emergence contours of the restoration. The provisional is usually made from heat-polymerized polymethyl methacrylate on the basis of a provisional titanium abutment. The material is contoured and highly polished to minimize plaque accumulation and tissue irritation.
If implant axis correction is necessary, customizable temporary polymer abutments with a titanium base are used. They are contoured in their transmucosal portion according to the desirable emergence profile. The cervical shoulders are prepared to follow the soft-tissue margins. Deep subgingival preparation is contraindicated due to risk of cement impaction into the peri-implant soft tissues (Figure 5).
There is little evidence in the current literature regarding the best techniques for peri-implant soft-tissue conditioning. The authors recommend the dynamic compression method.17 In the initial phase of tissue shaping, it is important to create some pressure on the peri-implant mucosa. Care needs to be taken to not over-contour the restoration in the interproximal area. Otherwise, there will not be space for papillary tissues to fill in. This method relies on creating initial pressure by adding material followed by a periodic reduction in the interproximal area to create space for the papilla. Reducing the contours of the provisional restoration can be performed intraorally with fine diamond burs, followed by polishing with a white Arkansas stone. This can be done in steps over several appointments if needed (Figure 6)
The Final Restoration
After completion of the soft-tissue conditioning and maturing phase—which can take several weeks or even months, depending on the tissue volumes to be conditioned—it is important to transfer the created soft-tissue architecture to the master cast by using customized impression copings, as described by Elian and colleagues (Figure 7).18
Consequently, the identical soft-tissue profiles are created in the master cast as established intra-orally, facilitating the fabrication of the final implant restoration according to the design tested with the provisional restoration (Figure 8 and Figure 9).
Conclusion
The implant-supported provisional restoration is designed to:
• create an accurate restorative emergence profile in the peri-implant mucosa.
• optimize the proximal contact location relative to the adjacent natural tooth or prosthetic crown.
• regenerate adequate papillae in height and width.
• establish peri-implant mucosal margins in harmony with the gingival contours of the adjacent teeth.
The provisional also serves as a communication tool for patient, dentist, and dental technician to optimize the esthetic result of the final restoration, which includes determining the position of the dental and facial midline; the final position of the incisal edge(s); the width, length, and contours of the implant crown(s); and proper tooth proportions when multiple teeth need to be replaced or restored.
References
1. Cho SC, Shetty S, Froum S, Elian N, Tarnow D. Fixed and removable provisional options for patients undergoing implant treatment. Compend Contin Educ Dent. 2007;28(11):604-609, 624.
2. Weber HP, Morton D, Gallucci GO, et al. Consensus statements and recommended clinical procedures regarding loading protocols. Int J Oral Maxillofac Implants. 2009;24 Suppl:180-183.
3. Grütter L, Belser UC. Implant loading protocols for the partially edentulous esthetic zone. Int J Oral Maxillofac Implants. 2009;24 Suppl:169-179.
4. Chen ST, Buser D. Esthetic outcomes following immediate and early implant placement in the anterior maxilla—a systematic review. Int J Oral Maxillofac Implants. 2014;29 Suppl:186-215.
5. Cordaro L, Torsello F, Roccuzzo M. Implant loading protocols for the partially edentulous posterior mandible. Int J Oral Maxillofac Implants. 2009;24 Suppl:158-168.
6. Buser D, Chappuis V, Bornstein MM, et al. Long-term stability of contour augmentation with early implant placement following single tooth extraction in the esthetic zone: a prospective, cross-sectional study in 41 patients with a 5- to 9-year follow-up. J Periodontol. 2013;84(11):1517-1527.
7. Bornstein MM, Wittneben JG, Brägger U, Buser D. Early loading at 21 days of non-submerged titanium implants with a chemically modified sandblasted and acid-etched surface: 3-year results of a prospective study in the posterior mandible. J Periodontol. 2010;81(6):809-818.
8. Belser UC, Bernard JP, Buser D. Implant-supported restorations in the anterior region: prosthetic considerations. Pract Periodontics Aesthet Dent. 1996;8(9):875-884.
9. Buser D, Martin W, Belser UC. Optimizing esthetics for implant restorations in the anterior maxilla: anatomic and surgical considerations. Int J Oral Maxillofac Implants. 2004;19 Suppl:43-61.
10. Cooper LF. Objective criteria: guiding and evaluating dental implant esthetics. J Esthet Restor Dent. 2008;20(3):195-205.
11. Belser UC, Grütter L, Vailati F, et al. Outcome evaluation of early placed maxillary anterior single-tooth implants using objective esthetic criteria: a cross-sectional, retrospective study in 45 patients with a 2- to 4-year follow-up using pink and white esthetic scores. J Periodontol. 2009;80(1):140-151.
12. Kan JY, Rungcharassaeng K, Fillman M, Caruso J. Tissue architecture modification for anterior implant esthetics: an interdisciplinary approach. Eur J Esthet Dent. 2009;4(2):104-117.
13. Chu SJ, Tarnow DP, Tan JH, Stappert CF. Papilla proportions in the maxillary anterior dentition. Int J Periodontics Restorative Dent. 2009;29(4):385-393.
14. Kan JY, Rungcharassaeng K, Umezu K, Kois JC. Dimensions of peri-implant mucosa: an evaluation of maxillary anterior single implants in humans. J Periodontol. 2003;74(4):557-562.
15. Kokich VO Jr, Kiyak HA, Shapiro PA. Comparing the perception of dentists and lay people to altered dental esthetics. J Esthet Dent. 1999;11(6):311-324.
16. Wittneben JG, Weber HP. Prosthodontic considerations and treatment procedures. In: Wismeijer D, Chen S, Buser D, eds. ITI Treatment Guide, Vol. 6: Extendend Edentulous Spaces in the Esthetic Zone. Berlin: Quintessence Publishing Co.; 2012:65-91.
17. Wittneben JG, Buser D, Belser UC, Brägger U. Peri-implant soft tissue conditioning with provisional restorations in the esthetic zone: the dynamic compression technique. Int J Periodontics Restorative Dent. 2013;33(4):447-455.
18. Elian N, Tabourian G, Jalbout ZN, et al. Accurate transfer of peri-implant soft tissue emergence profile from the provisional crown to the final prosthesis using an emergence profile cast. J Esthet Restor Dent. 2007;19(6):306-315.
About the Authors
Hans-Peter Weber, DMD
Professor and Chair
Department of Prosthodontics and Operative Dentistry
Tufts University School of Dental Medicine
Boston, Massachusetts
Thomas Sing, MDT
Oral Design New England
Boston, Massachusetts
