February 2009, Volume 5, Issue 2
Published by AEGIS Communications
A Five-Step Protocol for Immediate-Load Implant Treatment Planning
Aria Irvani, DDS
Several studies, such as Lindeboom et al,1 have demonstrated that placement of immediate-load implants is a viable treatment alternative. Enough data has been collected to support the long-term success of these types of restorations.2 This type of treatment is particularly useful when replacing a tooth in the esthetic zone. It has the advantage of decreasing the healing period, minimizing the resorption of alveolar bone, and decreasing the number of surgical procedures.3,4
The ability to provisionalize the implant also immediately allows patients to leave the office with a natural-looking dentition without a removable appliance throughout the healing phase. From a psychological standpoint, immediate provisionalization helps give patients a better sense of well-being and a greater appreciation for implant therapy.
To achieve the best result, the author recommends dividing the process into distinct steps:
- Step 1: Initial consultation and data collection
- Step 2: Bone and hard-tissue analysis
- Step 3: Soft tissue/bone relation analysis
- Step 4: Patient treatment presentation
- Step 5: Surgical and restorative treatment planning and fabrication of a surgical guide
Depending on how an office is run and the experience of the dentist, some of the steps can be consolidated. However, the steps serve as a useful template whether one implant or multiple implants are planned.
As with any implant treatment, planning is vital to success. The first step in this process is adequate data collection. A complete medical and dental history, quality diagnostic casts, photographs, and a computed tomography (CT) scan or panoramic radiograph is essential. After the data is obtained and analyzed, a separate consultation appointment is needed to go over the findings with the patient. It is at this appointment that the patient’s desires and expectations need to be discussed in detail, and the clinician needs to address the patient’s concerns in a manner that coincides with surgical and clinical reality. The mantra of under-promising and over-delivering never holds truer than during this visit. One treatment conference method that is becoming increasingly commonplace is the use of presentation software, such as Microsoft® PowerPoint. By enabling the patient to view photographs of his or her condition on the screen, the patient can have a better appreciation of the current condition(s) and understanding of the treatments that will be proposed at the treatment planning appointment. A more sophisticated user of the software can use animation to point out details and nuances.
Following the format outlined above, the next step is to determine the quality and quantity of bone available (the hard-tissue assessment). The amount of available bone will determine whether any augmentation is needed. With the predictable techniques available today, the existing bone will no longer be the absolute determining factor in implant placement.
The third step is to identify the patient’s gingival biotype (ie, thick vs thin and square vs ovoid), and the relationship of the implant site to the adjacent teeth, alveolar crest, and smile line (soft tissue/ bone relationship assessment).5,6 After considering these factors, the case can be classified as high risk (most likely to have esthetic or restorative complications) or low risk (most likely to have favorable results).5,6 Obviously, there will be cases that will fall in between these extremes.
The fourth step is to relay the findings to the patient in a manner that is understandable to him or her. As part of the treatment planning presentation, potential complications, length of treatment, and less than ideal starting points need to be reviewed in detail. This discussion is the cornerstone of any informed consent.
The final phase in the process is surgical and restorative planning of the accepted treatment plan, using the data collected. It is at this time that an impression of the patient’s existing dentition is made in order to fabricate a surgical guide. In the case presented here, the tooth to be extracted was in an ideal position and it would provide an excellent guide to making the surgical stent.
Treatment Planning Phase
The following case was planned and completed using the steps described. A 27-year-old woman presented with the chief complaint of “chipping in the back of her tooth.” She initially thought that this was caused by a missing filling, but closer examination revealed that there was a defect on the lingual side of tooth No. 8 along the gingival margin (Figure 1). A periapical radiograph revealed extensive external resorption (Figure 2). The patient stated that the tooth had been avulsed 8 years earlier as the result of an accident and was subsequently treated with root canal treatment, internal bleaching, and a porcelain laminate. During the data collection appointment, appropriate periapical radiographs were taken, and a panoramic film, diagnostic casts, and complete medical and dental history were obtained. The patient exhibited excellent oral hygiene and periodontal condition. After the records were taken, the data was analyzed. The second step involved determining the quality and quantity of bone. For this case, minimally traumatic extraction and immediate placement was preferred because of its favorable outcome,7 and the factors considered based on the known indications and contraindications of this treatment modality. The contraindications for immediate implant placement that should be considered include6: acute infection; if the implant cannot be anchored more than 3 mm beyond the extracted tooth socket for primary stability purposes; or if there is significant gingival recession mesiodistally and apicogingivally.
This patient presented with no periodontal defect, ridge atrophy, or present infection. The factors taken into account were the size of the extraction socket, gingival thickness and the neck size of the contralateral tooth. The author also gathered data to determine the appropriate size implant.
To determine the proper implant size, the horizontal (mesiodistal), vertical (apicocoronal), and sagittal (buccolingual) measurements were taken. The horizontal distance (between adjacent lateral and central) was 10 mm. Therefore, placing a 5-mm diameter implant would leave 2.5 mm from the edge of the implant to each of the adjacent teeth. This amount of space would satisfy the minimum 1.5-mm distance requirement.8 This minimum is one of the essential requirements to preserve the soft-tissue papilla between the implant and the adjacent teeth. Another helpful method is to check the width of the neck of the contralateral tooth and the extracted tooth to determine the implant diameter. The vertical measurement has two components, apical and coronal. The apical position of the implant is dictated by anatomical structures. In this case, the distance from the crest of the ridge to the base of the nasal cavity was 17 mm. This distance would provide adequate space to place a 13-mm length implant with 4 mm of clearance from the anatomical structures. The coronal component is the distance from the top of the implant to the free gingival margin. A 13-mm implant would have sufficient length to engage 3 mm of bone beyond the socket area. The research indicates that a minimum of 3 mm of intimate contact is needed between the implant and bone to achieve predictable osseointegration in immediately placed implants.9,10 The sagittal (buccolingual) component is the last part of the three-dimensional positioning of the implant that requires consideration. The diameter of the implant and actual buccolingual positioning of the implant affect this measurement. Improper positioning can have severe prosthetic and soft-tissue complications. In this case, a 5-mm diameter implant would fulfill that requirement.
There are many implants on the market that would provide a solid, stable platform and satisfy the size requirement. The author chose a 5-mm x 13-mm Replace® Select Tapered (Nobel Biocare USA, LLC, Yorba Linda, CA) for its ease of use. This implant has a TiUnite surface all the way to the top of implant platform. Because of the concavity of the buccal plate in the anterior maxilla, a tapered implant was preferable because it more closely follows the bony contours. The use of a straight implant may cause perforation through the buccal plate in the apical third.
As part of the hard-tissue assessment, potential complications were also evaluated. This included the possibility of grafting if the void between the implant and the socket walls (particularly the buccal plate) ended up being excessive. To be prepared to address potential buccal plate fracture during the extraction process, the necessary instruments and materials would need to be ready in the surgical set- up to repair the defect in case the buccal plate was damaged.
Next, attention was focused on step three, the soft tissue/bone relationship assessment. The anterior maxilla presents one of the most challenging areas for implant placement because of esthetic demands. In most cases, the buccal segment has a concavity in the bony architecture that makes implant placement very technique-sensitive.
The full-smile photographs revealed a very high smile line with a great deal of gingival display, which would classify the case as challenging. Then, the patient’s biotype was examined and classified as thick with square-shaped scallops around the teeth. This biotype is desirable (as opposed to thin, ovoid scalloped tissue) because it is less prone to recession after surgical procedures.5 One of the easiest ways that has been suggested for determining the thickness or thinness of gingival biotype is to place a periodontal probe in the sulcus. If the probe is somewhat visible through the gingiva and the tissue appears friable, the gingiva is classified as thin biotype. The most unpredictable and least desirable combination is a patient with a high smile line, ovoid, highly scalloped gingiva, and thin biotype. In this case, the high smile line was offset by a thick, square, gingival biotype, which placed the patient in the middle of the spectrum as far as the difficulty of the case was concerned. Of course, the patient’s attitudes and expectations can substantially increase or decrease the difficulty of the case.
The author discussed the findings with the patient (step four). During this presentation appointment, upper and lower polyvinyl siloxane impressions were taken (without any modification to the adjacent teeth), and the laboratory was instructed to remove tooth No. 8 from the model and fabricate a Maryland bridge as a backup provisional method. The patient was then scheduled for surgery.
Step five addressed planning the surgical and prosthetic details of the treatment. Two of the greatest advantages of extraction and immediate implant placement are preserving soft-tissue form and reducing the potential for recession. It has been determined that when a flap is reflected, there is the potential for loss of soft tissue in the surgical area.11 Therefore, direct placement of an implant into the extraction site should alleviate the need for flap reflection, minimize postoperative discomfort, and create the conditions for faster healing provided that the extraction is done with minimal disturbance to the soft tissue. This step also tackles provisionalization issues as they relate to the implant during the healing phase. The possibility of a lack of initial implant stability and subsequent two-stage placement were also explored.
Redundancy and having alternate plans is always desirable when performing any surgical procedure. In this case, the patient rejected the idea of an interim plate replacing tooth No. 8, in case the implant crown could not be temporized. She wanted a fixed solution. The only other remaining option was a temporary Maryland bridge.
At the surgical appointment the patient was anesthetized using a local anesthetic infiltration on the buccal and palatal gingiva. A soft-putty impression of the upper anterior arch was made for provisional fabrication, in the same manner as for a traditional crown-and-bridge provisional. Because of extensive loss of tooth structure from external resorption, great care was taken not to exert any forces that were not directed along the long axis of the tooth to prevent root fracture. Using a periotome, the periodontal fibers were severed circumferentially. The tooth was rotated clockwise and counterclockwise, being careful not to exert any pressure against the buccal plate. After the tooth was extracted (Figure 3), the socket was completely debrided to ensure that no remnants of periodontal fibers or other tissue that may interfere with osseointegration remained. The distance from the buccal alveolar crest of the extraction socket to the free gingival margin was measured. A distance of 3 mm (4.5 mm on the proximal surfaces) is desirable because it provides the most predictable outcome.5,6 Variations from these distances may result in tissue recession after implant placement. In this case, the distance was 3 mm from buccal alveolar crest to the free gingival margin. The same measurement was used for apicocoronal placement of the implant. At this time, the surgical template was placed over the upper arch to initiate the osteotomy process. Using a Lindemann side-cutting bur, the palatal wall of the socket was scored and a pathway was created for the 2-mm pilot drill and subsequent larger osteotomy drills. Great care was taken during each osteotomy to ensure that the implant would be centered mesiodistally. Throughout the procedure, copious irrigation was used to avoid excessive heat generation. After the site was prepared to 5 mm x 13 mm, the corresponding implant was placed into the site and torqued to 40 Ncm. The last few turns were done by hand instead of using the handpiece for better tactile feedback. The top of the implant platform was placed 3 mm apical to the free gingival margin of the extraction site (Figure 4). After the implant was secure, the distance between the facial aspect of the implant and the buccal plate was measured at 2 mm. It is absolutely critical that no pressure is exerted by the fully seated implant on the buccal plate because this pressure frequently results in resorption of the plate, which is usually followed by gingival recession. Because the gap between the buccal plate and implant surface was 2 mm or less in some areas, no grafting was deemed necessary.12,13
Previously, the patient mentioned that she may relocate before the completion of the prosthetic phase; therefore, the option of a temporary abutment was disregarded. This way, if the patient moved out of the area before completion of treatment, her new dentist simply could remove the provisional, make a traditional crown-and-bridge impression, and fabricate the crown.
A 5.0 Esthetic abutment by Nobel Biocare was modified outside the mouth and tried in to ensure proper reduction. After the proper modifications were made to the abutment, it was screwed lightly to the implant (Figure 5). A putty matrix was filled with Luxatemp® (Zenith/DMG Brand Division, Foremost Dental LLC, Englewood, NJ) in the area of tooth No. 8 and placed over the modified abutment. After 1 minute of setting time, the putty matrix was taken out of the mouth; the semi-hard provisional was removed from the putty and trimmed (Figure 6). The abutment was removed from the implant. Then, the provisional was placed on the modified abutment outside the mouth and any flash or excess was trimmed to avoid irritation and subsequent tissue inflammation. The abutment was placed back on the implant and torqued to 35 Ncm. The provisional was taken out of occlusion in centric and excursive movements, and the buccal emergence profile was slightly under-contoured to aid gingival healing. Finally, the polished and finished provisional was cemented to the abutment with temporary cement (Figure 7). The temporary prosthesis is an important step in the process used for laboratory communication, soft-tissue development, and gauging patient expectations.14
As fate would have it, the patient did not move out of the area. She was seen in 8-week intervals to have the implant checked (Figure 8). Approximately 6 months after placement of implant, the abutment was removed, final impressions were made using an open-tray technique (Figure 9), and the metal abutment was placed back on the implant but only torqued to 20 Ncm, and the provisional was re-cemented. The esthetic demands of the case made an all-ceramic abutment and crown a viable option.15,16 A Procera® Esthetic abutment (Nobel Biocare), which is made from zirconia, was prepared in the laboratory and a Procera crown was fabricated (Figure 10 and Figure 11).
In the final seating appointment, the metal abutment was removed, the zirconia abutment was tried in (Figure 12), and a verification radiograph was taken (Figure 13). When the proper fit was confirmed, the abutment was torqued to 35 Ncm and the Procera crown was cemented using implant cement (Figure 14). Only a very thin layer of cement was applied to eliminate the possibility of cement extrusion beyond the crown margins. Figure 15 shows the restoration 2 years after initial cementation and, although there was some gingival recession, the patient was very pleased with the outcome. Figure 16 is a radiograph of the implant 2 years postoperatively showing minimal bone loss. Although some recession may be inevitable, (a thin buccal plate, thin or unfavorable biotype, an over-contoured provisional or permanent restoration, or an excessive gap between the implant and the buccal plate) over-correction of soft- or hard-tissue contours must be considered. The use of mineralized freeze-dried bone to fill the space between the buccal plate and the implant surface may have reduced the amount of recession. Another predictable method to minimize recession is the use of connective tissue graft, which adds soft tissue volume and acts as a barrier membrane to promote osseous regeneration in the buccal area.
Implants have become a mainstay of modern dentistry. Not long ago a similar case would be restored using a traditional bridge, which would have caused unnecessary injury to adjacent teeth. With the advent of immediate loading, patients can avoid long periods of edentulousness while the implant is integrating. Immediate loading of implants takes more planning and preparation, and alternate scenarios need to be considered (ie, inability to achieve initial implant stability for proper loading), and redundancies need to be put in place.
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About the Author
Aria Irvani, DDS
Private Practice in Cosmetic and Implant Dentistry
Lake Forest, California