Howe MS, Keys W, Richards D. Long-term (10-year) dental implant survival: a systematic review and sensitivity meta-analysis. J Dent. 2019; 84:9-21 https://doi.org/10.1016/j.jdent.2019.03.008
Moraschini V, Poubel LA, Ferreira VF, Barboza Edos S. Evaluation of survival and success rates of dental implants reported in longitudinal studies with a follow-up period of at least 10 years: a systematic review. Int J Oral Maxillofac Surg. 2015; 44:377-388 https://doi.org/10.1016/j.ijom.2014.10.023
Jung RE, Zembic A, Pjetursson BE Systematic review of the survival rate and the incidence of biological, technical, and aesthetic complications of single crowns on implants reported in longitudinal studies with a mean follow-up of 5 years. Clin Oral Implants Res. 2012; 23:2-21 https://doi.org/10.1111/j.1600-0501.2012.02547.x
Pavel K, Seydlova M, Dostalova T Dental implants and improvement of oral health-related quality of life. Community Dent Oral Epidemiol. 2012; 40:65-70 https://doi.org/10.1111/j.1600-0528.2011.00668.x
Brånemark PI, Hansson BO, Adell R Osseointegrated implants in the treatment of the edentulous jaw. Experience from a 10-year period. Scand J Plast Reconstr Surg Suppl. 1977; 16:1-132
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; 33:447-455 https://doi.org/10.11607/prd.1268
Buser D, Belser U, Wismeijer D. ITI treatment guide; v.1: Implant therapy in the esthetic zone, single-tooth replacements.Portland: Ringgold Inc; 2007
Furze D, Byrne A, Alam S, Wittneben JG. Esthetic outcome of implant supported crowns with and without peri-implant conditioning using provisional fixed prosthesis: a randomized controlled clinical trial. Clin Implant Dent Relat Res. 2016; 18:1153-1162 https://doi.org/10.1111/cid.12416
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Shor A, Schuler R, Goto Y. Indirect implant-supported fixed provisional restoration in the esthetic zone: fabrication technique and treatment workflow. J Esthet Restor Dent. 2008; 20:82-97 https://doi.org/10.1111/j.1708-8240.2008.00156.x
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Provisional restorations provide numerous advantages during dental implant treatment including manipulation of the peri-implant soft tissue contour to optimise the aesthetic outcome. Chairside construction expedites this stage of the treatment to a single visit for the benefit and convenience of both the dental practitioner and patient. Additional laboratory costs typically incurred for this stage are also avoided. As the expectations and demands for restorations of implants continue to increase, in terms of time, cost and aesthetic outcome, this chairside approach is an important technique for the armamentarium of a dental implant practitioner.
CPD/Clinical Relevance: This chairside technique allows dental implant practitioners to provide aesthetic provisional implant crowns in a single visit.
Article
Endo-osseous implants are frequently advocated to replace missing teeth above traditional tooth replacement options, such as conventional fixed bridges. Implant-supported prostheses are highly successful with biological and functional benefits.1 A recent systematic review estimated a dental implant's 10-year survival rate to be 93.2%,2 in line with previous systematic reviews.3,4 Furthermore, for single-tooth replacement in the aesthetic zone (the dentition displayed on full smiling), implant restorations have been illustrated to significantly improve a patient's oral health-related quality of life.5 Major drawbacks of this treatment modality include that it can incur a greater financial burden and involve increased treatment duration compared with alternative treatment modalities.
There is a drive from both patients and dental practitioners to deliver implant-supported restorations within shorter timeframes, particularly in the aesthetic zone. The conventional, staged provision of implant treatment is being challenged by more expedited contemporary approaches to management.6 Significant advantages can be procured by the chairside construction of a provisional implant crown because it allows this critical stage, for optimizing treatment outcomes, to progress more efficiently. This article illustrates how this can be achieved.
Aims of provisional implant crowns
Provisional implant crowns serve a variety of functions. As with conventional provisional crowns, they allow a trial phase of the prosthodontic management, to verify that the patient and dental practitioner are both satisfied with form, function and appearance of the restoration. Refinements to the provisional restoration aimed at enhancing these aspects can be undertaken during this stage, prior to proceeding with the definitive restorative phase of treatment.7
Provisional implant crowns have important additional roles in relation to the support and shaping of the surrounding peri-implant mucosa. They can be used to define the transition between the top of the dental implant fixture and the shape of the prosthetic tooth at the gingival level, commonly referred to as the emergence profile. This can be modified easily in the provisional restorative phase of treatment to direct the gingival margin positioning and contour to replicate contralateral sites enhancing the aesthetic outcome. Additionally, the contour of the provisional crown can be refined to determine the tooth shape and contact-point position with the adjacent teeth, allowing infill of the interdental papilla area with peri-implant mucosa.8
Several methods can then be employed to transfer information about the optimised provisional implant crown to the technician for the definitive restorative phase. These would include using a customized impression coping technique to replicate emergence profile if a master impression was being used, or with the use of supplemental records of the provisional crown contour either via intra-oral scanning or dental impression.9
A randomized controlled clinical trial found that for single-implant crowns a provisional restorative phase with soft-tissue conditioning significantly improved the aesthetic outcomes of the final prosthesis.10 Advising dental practitioners to consider incorporating this provisional restorative phase into their implant practice, particularly when the aesthetic outcome of the case is paramount.
Selecting the method of provisional implant restoration construction
There are two main methods of provisional implant restoration construction:
Laboratory construction, via conventional fixture-level dental impression or 3D intra-oral scan;
Chairside construction.
This article presents a method for chairside construction of a screw-retained provisional fixture-level implant crown.
Clinical method
Preparation
Typically, as part of case planning for the implant treatment, the intended form of the final restoration would be depicted in wax on a cast of the patient's teeth and soft tissues, often referred to as a diagnostic wax-up. This provides a blueprint during the preliminary planning phases of treatment and visualization of the intended prosthodontic tooth contour and positioning. The presented technique uses this blueprint, via a sectional vacuum-formed matrix of the diagnostic wax-up, as a starting point for the development of the coronal form of the restoration. The armamentarium required for this chairside technique is detailed in Table 1.
Laboratory work
Equipment
Materials
Pre-operative diagnostic wax-up of intended tooth position
Gallipot
Chlorhexidine gluconate mouthwash
Sectional vacuum-formed matrix of the diagnostic wax-up
Implant prosthetic screwdriver and torque wrench
Polyvinyl siloxane putty
Turbine and slow-speed handpieces
Poly-tetra-fluoro-ethylene (PTFE) tape
Light-curing unit
Chemically cured bis-acryl provisional resin material, or similar
Temporary cylinder abutment
Composite finishing burs and polishing burs, discs and paste
Light-cured flowable composite resin
Temporary cylinder abutment screw
Miller forcep, occlusal recording paper and shimstock
Temporary access filling material (transparent addition cured polyvinyl siloxane)
As part of the preparation, polyvinyl siloxane putty was used to make a sectional matrix of the diagnostic wax-up in advance. It was sectioned through the mid-labial to mid-palatal aspect, for use in gauging the future modification of the temporary cylinder.
Chairside stages
Temporary cylinder abutment modification
Following healing abutment removal (Figure 1and irrigation with chlorhexidine gluconate (Corsodyl 0.2% mouthwash, GlaxoSmithKline, UK), the temporary cylinder abutment was screwed into position (Figure 2a). Determining the requirement for, as well as extent of, modification of the temporary cylinder was gauged via the use of the sectioned putty matrix of the wax-up, which had been prepared pre-operatively (Figure 2b). Following removal of the temporary cylinder, at the chairside, this was carefully adjusted using coarse and then smooth diamond burs. This adjustment ensured that the temporary cylinder, when reinserted, was just out of contact with the putty matrix (Figure 2c, d). During this stage, it is important to maintain adequate height of the temporary cylinder, as preservation of its retentive features optimises fixation of the provisional restorative material subsequently used.
Figure 1. Healing abutment in place and healed peri-implant mucosa. (a) anterior and (b) occlusal views.Figure 2. Customizing the temporary cylinder abutment. (a) The unaltered temporary cylinder with grooves that provide macro-mechanical retention to the temporary crown material. (b) The cylinder initially prevented the putty index from completely seating. (c) The height of the cylinder was reduced to allow (d) the putty index to completely seat. This ensured that the cylinder did not extend beyond the planned prosthodontic contour or interfere with the patient's occlusion. On a practical note, when modifying the height of the cylinder, an alternative to using college tweezers for purchase on the cylinder would be to screw the cylinder to an implant analogue.
Coronal crown construction
The sectional vacuum-formed matrix of the diagnostic wax up was assessed for seating, stability and adaptation with the modified temporary cylinder in place (Figure 3).
Figure3.
(a) Labial and (b) occlusal views of the vacuum-formed matrix try-in/verification. This had been trimmed to the gingival level labially and slightly supra-gingivally on the adjacent teeth to aid ease of removal and subsequent shaping refinement.
A mental note should be made at this stage of the position of the temporary cylinder's screw access channel (centre of the temporary cylinder, Figure 3b), as access to this will need to be made at a later stage once it is no longer visible.
Following packing of the temporary cylinder's screw access channel with PTFE (Figure 4a), a chemically cured, bis-acrylic composite resin (Integrity Temporary Crown and Bridge Material, Dentsply, USA) was used to fabricate the coronal portion of the crown, via syringing the resin into the vacuum-formed matrix prior to seating (Figure 4b).
Figure 4. Fabricating the provisional crown's coronal portion. (a) Packing of PTFE tape to provide a screw-covering intermediate spacer. (b) The seated vacuum-formed matrix containing provisional bis-acryl resin. (c) Screw access channel preparation. (d) Intermediate spacer (PTFE) removal to facilitate screwdriver access and retrieval of the unfinished provisional crown.
Once completely set, the vacuum-formed matrix was removed, and an access channel was created using the turbine and fine tapered diamond bur (Figure 4c) to the level of the PTFE tape within the temporary cylinder access channel. If the temporary cylinder was trimmed close to the matrix contour, then the outline of the temporary cylinder and spacer material may be visible, aiding this stage.
Following refinement of the access entrance to ensure that this was smooth and confluent with the rest of the cylindrical central access channel, the PTFE was removed (Figure 4d) to allow screwdriver access.
Subgingival crown construction
The method to fabricate the subgingival portion of the crown, creating the emergence profile to support the peri-implant soft tissue, is demonstrated in Figure 5. The emergence profile allows transition of the narrow, circular form of the temporary cylinder at the implant fixture, to the intended coronal form of, in this case, a maxillary lateral incisor. This emergence profile contour is shaped and polished to provide a curved, smooth, cleansable supportive transition. The form is less tapered closer to the implant, minimizing pressure and allowing space for the surrounding soft tissue. Typically, a narrower, less-contoured form is favoured, which can allow future modification to expand the emergence profile incrementally, balancing the effects with respect to soft tissue pressure. The subgingival profile of the crown was slightly under-contoured from the desired final emergence profile to work within the elasticity of the peri-implant mucosa (Figure 5c, d).
Figure 5. Extra-oral modifications of the provisional crown. (a) The initial coronal form to be refined following use of the vacuum-formed matrix shown in Figure 4b. (b) Following removal of excess composite, using fine diamond finishing burs and an air rotor/speed-increasing handpiece, to form the desired subgingival contour flowable composite resin (G-ænial Universal Flo, GC America) was incrementally added. (c) Interproximal view/profile of the developed provisional restoration. The resin's rheological properties and polishing allowed development of a smooth exponentially curved transition from the required coronal form to the apical aspect of the temporary abutment. The palatal emergence profile mimics the natural anatomy of the tooth-root form, whereas the buccal profile is more concave to predominantly support the overlying mucosa with its minimal displacement. (d) Labial view/profile of the developed provisional restoration. The proximal contours are more convex to develop interproximal papillae through the displacement of the surrounding mucosa in a lateral and coronal direction.
Following the extra-oral modifications, the provisional crown was tried-in and the final refinements were completed to optimise coronal form and occlusal conformity. Subsequently, the provisional crown was polished extra-orally using Sof-Lex finishing discs (3M/ESPE, UK) and an Enhance finishing point with polishing paste (Dentsply).
Delivery
The crown was then inserted using a temporary abutment fixture screw, torqued to 15 Ncm. The access screw channel was restored using a PTFE spacer over the screw head, leaving 3 mm of space coronally for a transparent addition-cured polyvinyl siloxane (Memosil 2, Kulzer, UK) provisional filling material. These materials are easily removed using a right-angled probe when retrieval of the provisional crown is subsequently desired. It is anticipated for the peri-implant mucosa to blanch initially (Figure 6). If the blanching was deemed to be excessive, then the progression of the emergence contour below the soft-tissue level may be reduced in order to make this more cylindrical. Keeping the emergence profile narrow initially can allow more space for the soft tissue.
Figure 6. Finalized screw-retained provisional implant crown, UL2. (a) Immediately after seating and (b) with reduced blanching of the peri-implant mucosa after 10 minutes.
Optimization
During subsequent visits the provisional implant crown is typically modified to further develop the emergence profile and condition the peri-implant mucosa, to optimize gingival aesthetics. Consideration of gingival margin heights, contour, zenith, as well as the tooth proportions and contour, are critical at this stage. Once the restoration achieves the patient's and dental practitioner's desired functional and aesthetic form, then this blueprint can be conveyed to the laboratory via the use of dental impressions or 3D intra-oral scanning to aid reproduction in the definitive restoration.
Discussion
This chairside clinical technique offers numerous benefits for the dental implant practitioner as summarized below:
Speed of restoration provision
At this stage of implant treatment, restoring the dental implant is the patient's main concern. Other than in instances when immediate implant loading is planned, the loaded provisional implant restoration is provided after a period to allow for osseo-integration of the implant fixture.9 This period with a provisional conventional tooth replacement prosthesis, frequently a partial denture, may lead to patient frustration and impatience, with a desire to expedite the restoration of the implant, which this chairside technique enables.
Number of clinical treatment sessions
As formal records and laboratory stages are avoided, this method can be used to provide a provisional implant restoration within a single appointment.
Patient satisfaction
Increased patient satisfaction is expected as their aesthetic desires and preferences can be shared with the dental practitioner and accounted for during the restoration fabrication.
Cost
This method offers an alternative to laboratory-manufactured provisional implant crown construction, using materials commonly used in general dental practices for the restoration of natural teeth and omitting the expense of a laboratory fee. In certain instances, this may lead to financial saving for the practitioner; however, this is anticipated to depend on the expense of the laboratory and, more significantly, the individual practitioners' skillset and experience. As the latter would influence the time required to construct a chairside provisional implant crown compared with the time required for the two clinical appointments to deliver a laboratory-manufactured provisional implant crown.
Control
What the restoring dental implant practitioner wishes to achieve in terms of supra- and subgingival contour of the provisional restoration, can potentially be delivered more efficiently and with greater control than construction via another party.
Accuracy
Chairside manufactured crowns have a lower potential for error in fit, including the form of the proximal and occlusal contacts, as they are fabricated directly.
Why choose a screw-retained provisional implant crown?
The use of a screw-retained implant crown provided in this manner offers the benefit of being simple to remove for subsequent clinical procedures, such as impression making, 3D intra-oral scanning, modification of the provisional crown and for placement of the definitive crown. They often require favourable implant positioning and angulation to enable this. Moreover, screw-retained provisional crowns avoid the use of cement, which eliminates the possibility of excess cement retained in situ and inducing peri-implant mucositis.11 Furthermore, cement-retained provisional implant crowns involve an additional implant component (separate implant abutment and crown) and thus introduce another interface where there is potential for failure.12
Technique modifications
The demonstrated clinical technique is straightforward, using, in many instances, existing skills and materials available to the GDP. Other provisional restorative materials, such as a more traditional chemically cured acrylic resin, could also be used to achieve similar results. However, the ease and convenience of the addition of flowable composite to bis-acryl resin would make these the materials of choice for this technique. The viscosity of flowable composite assists the production of the curved emergence profile desired (Figure 5c, d) when applied in the manner described. It has the additional benefit of being command set for immediate further addition or refinement.
For the presented case, a vacuum-formed clear matrix was used to create initial coronal form replicating the planned wax-up contour. It is appreciated that there are alternative methods for the fabrication of the coronal portion of the chairside provisional crown. These include using the transparent surgical guide, a polyvinyl siloxane putty matrix of the diagnostic wax-up or a Strip Crown Form (3M/ESPE).12 A disparate chairside technique uses a denture tooth that is modified with part of the acrylic removed from the palatal aspect to ensure its desired position is not impeded by the temporary cylinder abutment. The denture tooth is then adhered to the temporary cylinder abutment using chemically cured acrylic temporary crown material.13 A potential disadvantage of this approach would be the reliance of bonding multiple restorative material interfaces within the coronal portion, with the strength of the adhesion of the veneered component for the provisional restoration possibly being poor. Additionally, this may not necessarily mimic the planned restorative contour.
Peri-implant soft-tissue manipulation
When using chairside techniques, as well as producing an aesthetic coronal portion of the crown, we also need to consider the peri-implant soft-tissue support while developing the subgingival emergence profile of the restoration. The ideal emergence profile is gradual, with an obtuse angle, and requires approximately 3–4 mm in height.14 This desired emergence profile will support a natural buccal alveolar contour and ensure that the prosthesis is cleansable while not exerting excessive pressure on the mucosa.15 The latter two features reduce the risk of mucosal recession. The buccal emergence profile also varies according to the bucco–palatal position of the implant. If the provisional crown is more buccally or palatally placed, the buccal subgingival profile will be more concave or convex, respectively.16
When assessing soft-tissue aesthetics during provisional implant restoration, three features are fundamental:
The buccal alveolar profile of the mucosa;
The height and contour of the gingival margin, including the gingival zenith;
The interproximal papillae.
Manipulation of the gingival margin positioning and contour is possible through the sequential modification of the provisional restoration contour, for example, apical migration of the soft tissue is possible by making the subgingival profile more pronounced and vice versa. The way the restoration contacts with the adjacent teeth and coronal shape of the restoration are known to affect the presence or absence of interproximal papillae.17 Therefore, refining these properties of the restoration in the provisional phase, either at the time of fitting or incrementally over subsequent appointments, may optimize the soft-tissue aesthetics.
Conclusion
The presented clinical technique for chairside provisional dental implant crown construction offers a convenient, efficient and cost-effective means of providing an interim restoration. Fabrication at the chairside to a pre-determined contour with opportunity for subsequent modification uses familiar techniques and materials to the dental practitioner. This allows optimization of the dental and soft-tissue aesthetics to suit the patient's and dental practitioner's desires prior to proceeding to the definitive restorative phase of treatment.
