Anterior Implant - Supported Restorations: The Aesthetic Challenge

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Anterior Implant - Supported Restorations: The Aesthetic Challenge
April 2003
By E. Dwayne Karateew DDS
Oral Health Journal
The concept of osseointegration has evolved significantly since it was originally introduced by Branemark. The envelope has been continually expanded, such that now we are not only routinely performing successful single and multiple implant restorations, but both we, as professionals, and our patients expect aesthetic excellence.
If proper care in treatment planning and execution of those plans is not carried out then, the resultant prosthesis may appear to be less than desirable. This concept is most critical in the anterior portion of the mouth where hiding inadequacies may be more difficult. A few key strategies can be employed to ensure aesthetic success.
Osseointegrated implants were initially utilized for the replacement of full complement of teeth in a single arch.1,2 As this method of treatment eventually became increasingly predictable, applications shifted to partially edentulous situations and ultimately the focus became the single tooth restoration. The restoration of the single tooth implant is truly a complex task. A multidisciplinary approach is required throughout diagnosis, treatment planning, as well as the surgical and prosthetic phases, including all laboratory steps if one hopes to achieve a seamless aesthetic result with the adjacent dentition.3
The soft tissue contour is an inseparable component of this aesthetic ideal, as it is the gingivae, which forms the backdrop or the frame surrounding the teeth and underlying alveolus acts as the framework on which the final restoration can be staged.4
It is the preservation or reconstruction techniques utilized of this underlying osseous structure which eventually dictates the success or failure of the implant supported restoration from an aesthetic viewpoint.5 The absence of adequate osseous structure lateral to implant fixture can result in black triangles between the teeth, soft tissue and prosthesis, thereby compromising aesthetics.6 The labial gingival contour is supported and maintained by an adequate height and volume of labial bone. Although there exists techniques, which allow for alteration and amplification of deficient volumes of gingivae both interproximally and along the labial gingival contour, these surgical procedures alone may not provide sufficient bone for successful implantation.
There must be a concerted effort from all practioners involved with the case to identify potential soft tissue problems and develop strategies in the treatment planning stages to overcome them rather than waiting to address them at the end and ultimately falling short of the mark (Fig. 1).
TREATMENT PLANNING
Prior to the placement of an endosseous implant in the anterior portion of the mouth, there must be an effort to gain a comprehensive amount of information with respect to the facial, dental and periodontal dimensions. Facial analysis should include observation of the smile line and relative position of the commisures of the mouth.7 The dental analysis discerns the size, shape and mesio-distal as well as bucco-palatal positioning of the patients anterior teeth. Additionally, at this time observation and notation of the patients periodontal type, thick-flat or thin-scalloped should be made.8
The periodontal analysis involves the degree of bone and attachment loss of the site and of the adjacent natural teeth. Based upon these analyses, a diagnostic wax-up of the final restorative outcome can be performed and from this a surgical stent fabricated, which will dictate the ideal implant positioning.9 It is this stent which offers information regarding the three dimensional positioning of the implant in the edentulous space and will guide the necessity of tissue preservation or augmentation in the surgical phase.10
SURGICAL CONSIDERATIONS
It is paramount that the general surgical considerations must include atraumatic extraction, bone and soft tissue management11 and ideal implant placement guided by the surgical stent.3 If at all possible there should be a flapless surgical protocol, however, these applications are limited. Flapless implant surgery can only be achieved in conjunction with the immediate extraction of a tooth and the position of the underlying bone is ideal.12
If a flap must be raised to enable the visualization of the osseous architecture, or in the case of delayed implant surgery to facilitate the placement of an autogenous bone graft or other augmentation materials, tension free flap closure should be considered.13 As the area is healing, attention should be placed on making sure that there is no undo pressure on the soft tissues. In two stage protocols, additional soft tissue can be harvested from the palate to augment that which is present on the facial or interproximal aspects.14
PROSTHETIC CONSIDERATIONS
The three dimensional placement of the implant will directly impact the aesthetic success of the restoration. If the fixture is placed either too mesial or distal, or too labial or palatal the resultant prosthetic implications can mean the restoration is either over or under contoured. To enable the development of a proper emergence profile the fixture itself must be countersunk relative to the adjacent cemento-enamel junction, however, if placed too deep this can result in excessive loss of supporting osseous structure and the potential loss of the overlying gingival tissues.4
To improve predictability of presence of the interproximal tissues and the facial gingival margins a conservative approach should be utilized to preserve as much of the tissue as is possible. Continual pressure on the gingiva with the healing abutment, a provisional restoration15 and ultimately the final prosthesis should sculpt the tissue, rather than removal with a scalpel or the use of electrosurgical or laser units.
IMMEDIATE PLACEMENT AND GINGIVAL STABILIZATION OF A MAXILLARY ANTERIOR SINGLE IMPLANT
A Case Report
The loss of a single tooth in the anterior aesthetic region as a result of trauma, internal or external root resorption, periodontal disease, and/or endodontic failures in a patient with an otherwise healthy periodontium and complete dentition can be a traumatic experience.
More traditional guidelines have suggested that there be a two to three month healing period to allow for alveolar remodeling following the extraction of the failing tooth. This extended treatment period may not only be inconvenient to the patient, but more importantly, can lead to a loss of underlying osseous structure which will adversely effect the soft tissue profile.
A 50-year-old female patient presented with a vertical root fracture of the maxillary right central incisor (#11) and was advised that the tooth was hopeless and should be extracted (Fig. 2). The patient was informed of the available restorative options, which included a removable partial denture, fixed partial denture or an implant-supported restoration. No periapical radiolucency or symptoms of infection were evident during initial clinical and radiographic evaluation. Bone sounding did not reveal any discrepancies in the underlying osseous structure and there appeared to be a normal osseous gingival tissue relationship. Associated risks and benefits of treatment were discussed with the patient, and an immediate implant placement with gingival stabilization was selected.
Initial study models were taken and a provisional removable partial denture was fabricated to replicate tooth shape, colour and character. Tooth position was duplicated with the assistance of a silicon index which was useful to align the incisal edge position of the provisional prosthesis with respect to the original tooth.
Following administration of local anaesthetic, tooth #11 was atraumatically extracted without flap reflection using a Frialit-2 Periotome (Friadent, Lakewood, CO.) (Fig. 3). The controlled and deliberate extraction was facilitated without undo damage to the immediate surrounding gingival structure and without fracture of the labial alveolar bone, which was checked postextraction with a periodontal probe.
The osteotomy was performed to the appropriate depth, approximately 4-5 mm beyond the apex of the pre-existing tooth, and width, carefully preserving the integrity of the labial plate of bone. Primary implant stability was achieved by engaging the surrounding bone with the threads of the implant (Frialit-2, Friadent, Lakewood Co.). The implant itself was countersunk 6mm relative to the adjacent CEJ and 3mm relative to the surrounding osseous crest. The final implant angulation and mesio-distal placement was dictated by the extraction socket itself.
Gingival stabilization was achieved with a metal temporary abutment, which was connected and hand-tightened onto the implant. Flowable composite (Aeliteflo, Bisco Canada, Richmond BC) was injected into the sulcus surrounding the temporary abutment and cured for the appropriate length of time with a curing light (Optilux 501, Demtron-Kerr, Orange, CA). In this fashion the 3-D profile of the sulcus is reproduced in the composite and any voids in the material are later filled in on the lab bench (Fig. 4A).
This gingival scaffold is trimmed to be flush with the sulcular margin and is hand-tightened into place on the head of the implant (Fig. 4B). Appropriate antibiotics and analgesics were prescribed for the post-operative course of treatment.
The final restorative phase was initiated after three months of uneventful healing with a provisional partial denture in place (Fig. 5). The gingival scaffold was removed and an impression coping was fully seated onto the implant. The final impression was taken with polyvinylsiloxane (Affinis, Coltene Whaledent, Mahwah, NJ), along with a bite registration (Blu-Mousse, Parkell, Farmingdale, NY) and a counter model impression. It is not only important to record the position of the implant