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Articles: Same Day Dental Implants

Planning implant placement on 3D stereo-lithographic models applied with immediate loading of implant supported hybrid prostheses after multiple extractions: A case series by Ian Aires DDS

Published at PubMed here

 

PURPOSE:

The aim of this noninterventional, retrospective case series was to evaluate the outcome of immediately loaded implants in patients with failing dentitions that require bone tabling using a bone reduction guide and a surgical guide manufactured directly on three-dimensional (3D) stereolithographic models.

MATERIALS AND METHODS:

Consecutive patients with failing dentition and at least two remaining teeth who were treated in a single center between December 14, 2009 and September 23, 2013 were eligible. All patients receiving implants loaded with a hybrid prosthesis on the same day as extraction with their surgery planned on 3D models and performed using a surgical guide manufactured in a laboratory on the planning model were included. Patients who had undergone bone grafting procedures were excluded. Descriptive statistical analyses of available data were performed, including life-table calculations to derive a cumulative survival rate (CSR).

RESULTS:

Two hundred twenty-eight patients (105 females and 123 males) received 1,657 implants (NobelActive) in 321 arches, in most cases 5 implants (range, 5 to 7) per arch. Ten preexisting implants were used. The mean insertion torque was 60.02 ± 13.1 Ncm (range, 15 to 75 Ncm). The definitive abutment was placed on the same day as surgery in all cases, and the definitive prosthesis (n = 304) was delivered after a mean of 7.9 ± 2.6 months. All implants were followed for 20.01 ± 11.3 months (range, 0 to 52 months) from implant insertion. Four implants (3 patients) had delayed loading, and one implant was left as a sleeping implant. Eight implants among six patients failed, two of the implants after prosthesis delivery. The CSR of the placed implants was 99.4% at implant level and 96.2% at patient level.

CONCLUSION:

Planning on 3D models to remove bone and place implants using custom-made bone reduction and surgical guides with immediate loading on the same day as extraction of remaining teeth was safe and effective for implant survival and rehabilitation of patients with periodontitis and failing dentition.

Traditional dental implants in patients with advanced periodontal disease can be arduous, involving multiple surgeries, long treatment times, and high treatment costs. Therefore, many patients are unable to benefit from the use of dental implants. However, during the last decade, methods have been developed to simplify treatment by reducing the number of surgeries, treatment times, and associated costs .

During the healing process, implants become osseointegrated, and as their primary stability, which is purely mechanical, drops; simultaneously, the secondary stability (i.e., osseointegration) increases. Implants are vulnerable in this phase  . Modern moderately rough surfaces and grooves are osteoconductive and promote osseointegration, which maintains the high stability that was initially achieved throughout the healing process. Furthermore, modern implant designs allow for high primary stability (e.g., high insertion torque ≥ 35 N cm) and immediate loading of implants, even when placed in extraction sites (e.g., failing dentitions). Immediate loading with a hybrid prosthesis is now an accepted treatment option for the full arch in both the maxilla and mandible . Immediate loading has achieved excellent results with various implant systems .

Surgical guides can facilitate the accurate placement of implants during insertion procedures . These guides were initially produced by dental labs on gypsum dies. However, recent advances in CAD/CAM technology utilizing stereo-lithographic manufacturing of the guides have improved the production and shown a higher predictability of outcomes with better planning and accurate implant placement .

There is some evidence that placing the definitive abutment on the day of implant insertion can improve the chances of success. Further, patients with a failing dentition usually wish to get teeth that are functioning the same day of surgery. Patients report higher satisfaction during osseointegration of implants if they receive the prosthesis immediately compared to delayed loading protocols.

Implants can be placed in a tilted manner in contrast to the upright position of natural teeth Tilting implants allows use of longer implants and is enabled by “multi-unit-abutments. Furthermore, it spares areas such as nerves, sinuses, or vessels and allows a wider anterior-posterior spread to support the prosthesis, thereby reducing the extent of cantilevers, which can fracture and are unfavorable for loading implants . In addition, tilting can help avoid major bone grafting.  There is sufficient evidence that tilting does not adversely affect implant success .

Tilted implants and immediate placement of implants to replace failing dentitions are demanding procedures. Surgical templates facilitate placement of implants in the planned position and can be created with planning software using CT or CBCT data. Another option would be to plan and manufacture the guides on 3D stereo-lithographic models. Planning implant positions with computer-based methods and stereo-lithographic surgical templates achieves high cumulative survival rates (CSR) for implants at 1 year of follow up (9). However, to date, no study has planned the amount of bone reduction and placed the location of the dental implants directly on three-dimensional (3D) stereo-lithographic models. In such an approach bone reduction is first performed directly on the 3 D model by the oral surgeon. The surgeon then performs the implant osteotomies directly on the 3D models. This is followed by fabrication of both the bone reduction guide and the surgical guides.  The 3D model allows further evaluation of the planned placement according to the anatomical structure of the patient prior to actual placement and manufacture of the guide on that basis. Here, we performed a retrospective evaluation of implants placed and immediately loaded in a series of consecutive patients with failing dentition using both a bone reduction and a surgical guide that were manufactured directly on 3D models. 

 

The full study can be found here as a PDF download or at PubMed linked above.
The original publication source at JomI is here.

 


 

Simultaneous Immediate Placement and Immediate Loading of Dental Implants in the Maxilla: A Case Presentation

Ian Aires, DDS, and Joel Berger, DDS

Copyright 2002 Journal of the California Dental Association. 

 

The standard three- to six-month healing time for implants is no longer an absolute. In selected cases, it is now possible to load the implants in fewer than two months; and, in some cases, immediate loading is possible. This article contains a case study showing that with careful patient selection, immediate loading appears to be an acceptable technique.

 

The standard three- to six-month healing time for implants is no longer an absolute. In selected cases, it is now possible to load the dental implants in fewer than two months; and, in some cases, immediate loading is possible. The transition from early loading to immediate loading is now being made. This new thinking will rekindle the excitement of implant dentistry that was experienced in the early 1980s.

The protocol described by Adell and colleagues1 in their classic 15-year study prescribed a two-stage approach. The dental implant was buried for at least three months in the mandible and six months in the maxilla before loading with a prosthesis.

This standard has been used for 20 years with excellent long-term results.1-3 The protocol described by Branemark and Adell also recommended primary closure of the implant site, with no pressure being exerted on the tissue for at least one week.

New Thinking

1990

Almost 10 years after the publication of the 1981 15-year study of Branemark and Adell, Schnitman4 published a small study describing immediate loading of mandibular implants in nine patients.

Schnitman placed seven to eight implants per patient, three of which were immediately loaded with a fixed detachable hybrid prosthesis. The remaining four to five dental implants were buried in the standard two-stage protocol. After the standard four-month healing period, the buried implants were uncovered and the prosthesis attached. Although the initial results seemed promising, there was a statistical difference in the number of dental implants lost that were immediately loaded compared with those that were buried in the two-stage protocol.

1994

Henry and Rosenberg5 placed six mandibular implants each in five patients. Four of the six were loaded immediately with a provisional removable overdenture. At

seven weeks, a permanent prosthesis was placed. The results showed 100 percent success: All dental implants integrated.

1997

In 1997, Schnitman6 followed his initial study from 1990 with 10-year results of the original nine patients. Of the 28 immediately loaded implants, four were lost in four patients. None of the buried implants was lost. Most of the failed implants were short (7 mm in length) and were placed in poor quality bone in the posterior mandible.

Also in 1997, Balshi and Wolfinger7 reported on 10 patients in whom a total of 130 dental implants were placed. Of 40 immediately loaded implants, eight were lost, representing a 20 percent failure rate. Four of the buried dental implants were lost, representing a 4.4 percent failure rate. The 20 percent failure rate for the immediately loaded implants seemed unacceptable. However, the overall failure rate for all the dental implants was 9.2 percent.

A landmark study published by Tarnow8 showed for the first time immediate loading in the maxilla as well as mandible. Until this study, all the immediately loaded dental implants had been placed in the mandible. In this study, a minimum of 10 implants was placed per jaw. Initially, five were submerged for medicolegal reasons. Later, as it became apparent that the success rate was high, more implants were loaded. Of the 69 immediately loaded dental implants, 67 integrated. Of the 38 submerged implants, 37 integrated. Three dental implants were lost of 107 implants placed.

According to the authors, one implant was lost due to infection from an adjacent extraction site. Two were lost due to tapping off the provisional bridge during the initial three- to six-month healing period. Both of these implants had been placed in extraction sockets. Of the 10 patients completed, eight lost no implants.

The protocol described by the authors for immediate loading is as follows:

1. Only edentulous arches are to be used.

2. Dental Implants should be at least 10mm in length.

3. A diagnostic wax-up is necessary for a surgical guide and for fabrication of heat-processed provisional bridges. It is recommended to use a metal bar on the lingual aspect of the bridge for rigidity.

4. It is preferable that a screw-retained bridge be used. If a cemented bridge is used, it should not be removed for the duration of the healing period (three to six months).

5. The dental implants should be tested for stability at stage 1 with a Periotest instrument.

6. The widest possible anterior-posterior distribution should be sought.

7. No cantilevers should be used.

8. Cross arch splinting is mandated.

1998

In 1998, Lazzaro9 reported on 429 Osseotite implants placed in 155 patients. In this multicenter study, 10 centers reported on their results. The patients were followed for a mean of 10 months.

This was not a true immediately loaded technique. The dental implants were placed with a single-stage surgical technique but were loaded at two months. However, there was

no cross-arch splinting. Both single and multiple units were placed: 83 single dental implants and 129 multiple units of two, three and four implants. Seven out of 429 failed to integrate for a success rate of 98.3 percent.

1999

In 1999, Randow10 and colleagues reported on a study in 16 patients. Dental implants were placed only in the mandible. A total of 88 dental implants were placed with an average of 5.5 implants per patient. The implants were loaded after 20 days. At 18 months, all dental implants were successfully in function. In another study by Branemark11 in 1999, three implants were placed in the mandibles of 50 patients and immediately loaded. The system, Branemark Novum, includes specially designed surgical and prosthetic templates and superstructures. Of 150 implants placed, three failed to integrate. One prosthesis failed of the 50 fabricated.

A Case Report

With the information gathered from studies of early and immediate loading, the authors decided that there were enough data available to proceed with immediate loading in a private-practice setting. Case selection would obviously be an important factor in

proceeding with this new technique. The authors used the Tarnow protocol of immediate loading as their blueprint in case selection.

Case Selection

A 57-year-old female patient was referred for evaluation for dental implants. At the time of evaluation, the patient had a fixed restoration extending from tooth No. 2 to tooth No. 12. She was missing teeth Nos. 3, 4, 5, 6, 7, 8, 9, and 10. Tooth No. 2 was mesially inclined with a large periodontal defect as well as recurrent decay under the crown (Figure 1). The bridge was clinically loose. Teeth Nos. 11 and 12 could not be salvaged (Figure 2). The residual ridge had severe resorption in a buccal/palatal dimension. Vertically, there was adequate bone. A decision was made to reconstruct the patient with a fixed restoration using immediately loaded dental implants and a provisional restoration followed by a seven-month period of osseointegration and final restorations. Because of the narrowed arch, laminate grafts were planned to be done simultaneously with implant placement because it was believed the patient had adequate bone superiorly to get initial good stabilization of the implants.

The treatment plan involved the following:

1. Extracting the remaining maxillary teeth except for teeth Nos. 13 and 15, which were deemed to be periodontally and restoratively sound.

2. Placement of eight to 10 dental implants in the areas located between the right first molar across to the left first premolar.

3. Loading the implants immediately at the time of surgery with a heat-processed, metal-bar-reinforced provisional bridge.

4. Cementing the provisional bridge and retaining for six months before removal.

Laboratory Preparation

A number of steps were taken prior to the surgical placement. These included the following:

1. Face-bow recording and diagnostic assessment of implant placement. After the case was mounted on an articulator, implant positioning was determined. By correlating the panoramic radiograph and the position of the clinical crowns, the best positions for the implants were determined. It was evident that autogenous bone grafting would be required in certain locations.

It was determined that teeth Nos. 13 and #15 were sound. It was decided to retain these teeth and fabricate a three-unit fixed partial denture extending from No. 13 to No. 15.

2. Surgical guide fabrication (Figure 3). The patient was pleased with the esthetics of her existing fixed partial denture. Therefore, the fixed bridge was used as a guide to the desired position of the implant crowns.

3. Custom tray fabrication (Figure 4). An open-top tray was fabricated to allow for a pick-up type of impression. To reduce any stresses on the dental implant, a transfer type of impression was not used.

4. Heat-processed provisional bridge. This bridge was fabricated using the positioning and size of the existing fixed partial denture. The bridge was designed to be relined at the time of surgery and then cemented for six months.

A metal lingual bar was fabricated to help reinforce the provisional bridge.

5. Interim partial denture (Figure 5). Should it be determined at the time of surgery not to immediately load the implants, an interim partial denture was fabricated to replace teeth Nos. 3 through 12.

6. Selection of temporary titanium abutments and lab analogues. It was important to have a wide selection of abutments. Different diameter abutments would be needed if different diameter implants were used. Both straight and angled abutments were needed, as the likelihood was high that some of the dental implants would be facially inclined.

Surgical Procedures

The patient was taken to surgery in the authors’ outpatient surgery center and underwent hip graft with reconstruction of the alveolar width. With a previously constructed surgical guide using implant paralleling jigs and rings, the implants were placed in a previously determined position, based on a wax bite and diagnostic models. After the implants were placed, laminate grafts were placed to build up the palatal/buccal dimension and stabilized with screws. A bone chip (3 mm x 4 mm) was placed and tacked down to the available bone in the intraradicular bone between the dental implants of Nos. 8 and 9. This would help to support the papilla between those two teeth.

After an appropriate length of osseous integration, all the dental implants were uncovered, healing abutments placed, and the patient began the final restorative phase of treatment.

The most posterior implant on the left side was left buried and not uncovered because of the proximity to tooth No. 13, which would not allow a cosmetic and cleansable situation.

 

Prosthetic Treatment

Once all 10 implants had been surgically placed, the decision was made to load seven implants and allow the remaining three to heal submerged. The submerged implants were:

1. In the No. 3 area: This area required extensive bone grafting.

2. In the No. 4 area: an immediate extraction site

3. In the No. 11 area: an area of immediate extraction and implant placement. A large bone graft was placed over the facial aspect of this implant.

 

Impression

Impression copings were secured to the implants with long retaining screws, and the custom tray was loaded with a medium-body polyvinyl siloxane material. Once the material set, the screws were removed and the impression removed together with the impression copings (Figure 6).

Lab analogues were then screwed onto the impression copings, and a plaster cast was poured (Figure 7). This allowed the option of relining the case on a cast rather than directly in the mouth.

Appropriate temporary abutments were selected and seated on the implant analogues. The provisional bridge was then relined over the abutments. The abutments were then seated onto the implants (Figure 8). The occlusion of the provisional bridge was adjusted. This step was taken with much deliberation and care to ensure bilateral centric stops. A balanced occlusion was developed to allow working side contacts to be evenly distributed on as many implants as possible on the right side and on the natural teeth Nos. 13 and 15.

Cementation

The provisional bridge was cemented with Temerex cement. At one week, the patient was seen for a postoperative visit; and the occlusion was checked (Figure 9). Minor occlusal adjustments were made to perfect the bilateral centric stops and eliminate any lateral interference. The patient was seen weekly to check the occlusion and monitor the patient’s oral hygiene (Figure 10).

Uncovering the Implants

After an appropriate length of osseointegration, all the dental implants were uncovered, the healing abutments were placed, and the patient began the final restorative phase of treatment. The most posterior implant on the left side was left buried and not uncovered because of the proximity to tooth No. 13, which would allow a cosmetic and cleansable situation.

After an additional three weeks, final impressions of the dental implants and the two natural teeth were made. It became evident at the final impression stage that the implant in the No. 6 area was not osseointegrated, and it was removed (Figure 11). The remaining eight implants were used for a fixed bridge extending from tooth No. 3 to No. 12. A three-unit fixed bridge was fabricated to restore teeth Nos. 13, 14, and 15 (Figure 12).

The standard protocol for fabricating an implant-supported fixed partial denture was then followed (Figure 13).

The bridge was cemented with Temerex cement as final cement (Figure 14). This allowed the author to remove the bridge if necessary in the future.

Conclusion

The implants were placed on December 1998, and at the writing of the article, the case is at 25 months postoperative. The patient continues to do well with no apparent bone loss around the eight implants (Figures 15 and 16). The implant bridge has been stable since it was cemented in October 1999 with Temerex cement. The authors have subsequently restored two cases using the early loading protocol. The authors’ experience suggests that seating the provisional bridge two to three weeks after implant placement is less stressful for both the patient and the dentist. It also allows the dentist to have more time to fabricate the provisional bridge.

With careful patient selection, immediate loading appears to be an acceptable technique.

Authors

Ian Aires, DDS, has maintained a practice, limited to prosthodontics, in San Diego since 1981. He is founder and past president of the San Diego Prosthodontic Society, and he graduated from Boston University School of Graduate Dentistry.

Joel S. Berger, DDS, is an oral surgeon in San Diego.

References

1. Adell R, Lekholm U, Rockler B, A 15-year study of osseointegrated implants in the treatment of the endentulous jaw. J Oral Surg 10:387-416, 1981.

2. Branemark P-I, Breine U, et al, Intraosseous anchorage of dental prostheses. Part I: experimental studies. Scand J Plast Reconstr Surg Hand Surg 3:81-100, 1969.

3. Branemark P-I, Hansson BO, et al. Osseointegrated implants in the treatment of the endentulous jaw. Experience from a 10-year study period. Scand J Plast Reconstr Surg 16:1-132, 1977.

4. Schnitman PA, Wohrle PS, Rubenstein JE, Immediate fixed interim prostheses supported by two-stage threaded implants: Methodology and results. J Oral Implantol 16:96-105, 1990.

5. Henry P, Rosenberg I, Single-stage surgery for rehabilitation of the mandible: Preliminary results. Pract Periodontics Aesthet Dent 6:15-22, 1994.

6. Schnitman PA, Wohrle PS, et al, Ten-year results for Branemark implants loaded with fixed prostheses at fixture placement. Int J Oral Maxillofac Implants 12:495-503, 1997.

7. Balshi TJ, Wolfinger GJ, Immediate loading of Branemark implants in edentulous mandibles: a preliminary report. Implant Dent 6:83-8, 1997.

8. Tarnow DP, Emtiaz S, Classi A, Immediate loading of threaded implants at stage 1. Surgery in edentulous arches: ten consecutive case reports with 1 to 5 year data. Int J Oral Maxillofac Implants 12:319-324, 1997.

9. Lazzara RJ, Porter SS, et al, A prospective multicenter study evaluating loading of Osseotite implants two months after placement: one-year results. J Aesthet Dent 10(6):280-9, 1998.

10. Randow K, Ericsson I, et al, Immediate functional loading of Branemark dental implants. An 18 month study. Clin Oral Impl Res 10:8-15, 1999.

11. Branemark PI, Engstrad P, et al, Branemark Novum, A new treatment concept for rehabilitation of the edentulous mandible. Preliminary results from a prospective clinical follow-up study. Clin Implant Dent Relat Res 1(1):2-16, 1999.

To request a printed copy of this article, please contact/Ian Aires, DDS, 4130 La Jolla Village Drive, Suite 204, La Jolla, CA 92037.

Figures

Figure 1. Panoral radiograph shows the failed long-span fixed bridge and mesially inclined No. 2.

Figure 2. Occlusal view of the remaining natural teeth. Nos. 2, 4, 11 and 12 were not restorable.

Figure 3. Surgical guide to aid implant placement.

Figure 4. A topless custom tray was fabricated ahead of time to allow for a pick-up impression of the impression copings.

Figure 5. An interim partial upper denture fabricated to be used if immediate loading of the dental implants was not possible.

Figure 6. Pick-up of the impression copings after partial closing of the tissue flap.

Figure 7. Lab analogues are attached to the impression copings, and a solid cast is poured.

Figure 8. Titanium straight and angled abutments are seated onto the implants.

Figure 9. One-week postoperative, the provisional bridge is checked for occlusal interferences.

Figure 10. Weekly checks of the provisional bridge were made to perfect the bilateral centric stops and eliminate any lateral interferences.

Figure 11. At the final impression stage, it became evident that the dental implant in the No. 6 area was not integrated; and it was removed. The remaining eight dental implants were used to support a fixed bridge extending from tooth Nos. 3 to 12.

Figure 12. A three-unit fixed bridge was fabricated to restore teeth Nos. 13, 14, and 15.

Figure 13. Individual metal copings are seated on the abutments and joined with pattern resin.

Figure 14. The one-piece porcelain-fused-to-metal bridge is cemented with Temerex.

Figure 15. Radiograph demonstrates stable bone heights 25 months postoperative.

Figure 16. Eight implants support the fixed bridge with one premolar cantilever.

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