Creating the FP1 prosthesis: a systematic case study

Dr. Michael Freimuth discusses a technique for predictable and reproducible creation of the FP1 prosthesis

Introduction

As the world of implant dentistry continues to evolve, there are multiple treatment modalities to achieve clinical outcomes. The increasing use of social digital media and the Internet makes our patients exceedingly aware of the possibilities that exist. The awareness creates a perspicacious view of the results; in addition, the cost of the full-arch fixed restorations adds to the patients’ desire to be educated on their evolving expectations of treatment. There are countless articles and various franchises available offering full-arch fixed restorations and removable implant solutions. Some offer only one solution to all clinical situations, much like the track home method — cookie-cutter dentistry. As a practice, clinically how do we decipher the best treatment option and material for our patients? How do we custom-build a plan for our patients? What are the clinical determents necessary? Furthermore, what steps are essential to execute and achieve the desired results? The purpose of this article is to examine creating the FP1¹ prosthesis (when the fixed prosthesis replaces only the crown and looks like a natural tooth) or “custom-built home” in a systematic process.

Case description

A 65-year-old-female patient presented to the office with terminal dentition case Type III periodontitis² with Grade III mobility. The patient wanted a plan that would create an overall change in her oral health and esthetics. The evaluation was made utilizing clinical digital photography, digital radiographs, 2D and 3D CBCT (i-CAT) diagnostic models (maximum intercuspation position) — moreover, clinical, medical, periodontal, functional, dentofacial, and biochemical evaluations.³  The collective and collaborative decision was made to initiate treatment. Treatment began in the lower arch and was done to completion. The final result was an FP3 (when the fixed prosthesis replaces missing crowns and gingival color⁴). The patient was happy with the outcome; however, she was hoping to avoid pink porcelain on the maxilla due to added lingual thickness, and there was a phonetic concern as well. Maintaining the available bone and gingival architecture was highly desirable to the patient. Instituting this plan at this clinical juncture resulted in the FP1 prosthesis as a restorative possibility. After consent was obtained, the process of commencing and developing the roadmap to achieve the desired results began. Note that it is vital to coordinate and formulate all details and timelines with the patient, team, and laboratory. This begins the five stages of the FP1 treatment plan, prosthetic and surgical.

Figure 1: Preoperative full-face photo and Figure 2: Lateral view close-up

Figure 3: Preoperative radiograph

Figure 4: Retracted upper and lower arch pretreatment and Figure 5: Maxillary arch pretreatment

Prior to surgery

Prior to stage 1 surgery, the diagnostic models at the correct vertical dimension on the articulator with clinical photography were sent to the laboratory. Written and verbal instructions were communicated to the technicians.

Stage 1: surgery

Inaugural surgery and prosthetics included these steps:

• Preparation (predetermination for key implant positions) of the teeth to support the custom-milled shell polymethyl methacrylate (PMMA)⁵
• Atraumatic extraction of teeth in decisive positions
• Placement of endosseous implants⁶ in key positions with concurrent bone grafting
• Finishing this stage with placement of the custom temporary

The patient was given the following preoperative medications: amoxicillin 500 mg for 7 days and dexamethasone 0.4 mg for 3 days.⁷ At initial assessment, the patient consented to oral sedation with a protocol prescription of triazolam 0.25 mg and hydroxyzine 50 mg.

Anesthetic included 20% benzocaine topical for R/L-IA, LB. The total given was 3 cartridges of 2% lidocaine with epinephrine, 1:100,000 and 1 cartridge of 4% Septocaine® with epinephrine, 1:100,000, NADR.  Profound anesthesia was acquired.

Teeth Nos. 2, 6, 8, 9, 11, and 15 were prepped for prosthesis, and teeth Nos. 3, 4, 5, 7, 10, 12, 13, and 14 were extracted atraumatically with Luxator® (Directa Dental). Extraction sockets were debrided with curettes and flushed with chlorhexidine gluconate 0.12%. Osteotomies were performed into extraction sites, CAMLOG® implants (various diameters) were placed and torqued to 30Ncm. Cover screws were placed, and MinerOss® (BioHorizons®) allograft was placed into sockets;  BioPlugs (BioHorizons) were placed for graft containment. PMMA temporary was cemented on remaining teeth, and the temporary needed to remain for 4 months allowing for optimal HEALING. Postoperative instructions were given to the patient.

Figure 6: Stage 1 — tooth preparations for PMMA and Figure 7: Stage 1 — atraumatic extraction sites

Figure 8: Stage 1 — implant placements in key positions and Figure 9: Stage 1 — cover screw placed

Figure 10: Stage 1 — milled-shell temporary occulusal view and Figure 11: Stage 1 retracted frontal view — PMMA cemented in place on day of surgery

Figure 12: Stage 1 — postoperative radiograph day of surgery

Stage 2: surgical uncovering after 4 months of healing

The patient was anesthetized by placing 20% benzocaine topical for R/L- IA/L. The total given was 2 cartridges of 2% lidocaine with epinephrine, 1:100,000 and 1 cartridge of 4% Septocaine® with epinephrine, 1:100,000, NADR. Profound anesthesia was acquired.

The process began with removal of the temporary PMMA prosthesis. The implants were uncovered atraumatically utilizing a CO2 laser (DEKA). The impression copings were placed, and it was confirmed radiographically that they were fully engaged. A traditional full-arch impression with additional poly vinyl siloxane (PVS) silicone heavy- and light-body wash technique was taken, and impression copings were removed. A bite registration was obtained at the desired vertical dimension.⁸ Healing abutments were placed, and radiographs taken to confirm complete engagement. The PMMA-milled shell temporary was modified to go over the healing abutments, then cemented in place. The patient was given postoperative instructions and scheduled for removal of the remaining dentition. The impression and clinical digital photographs were sent to the laboratory along with the written script.

Figure 13: Stage 2 — uncovered with laser and Figure 14: Stage 2 — impression copings occlusal view

Figure 15: Stage 2 — impression copings frontal view and Figure 16: Stage 2 — PVS impression

Stage 3: surgical and prosthetic phase

A preoperative prescription protocol was prescribed for amoxicillin 500 mg for 7 days and dexamethasone 0.4 mg.

The patient was anesthetized by placing 20% benzocaine topical for R/L- IA/L. The total given was two cartridges of 2% lidocaine with epinephrine, 1:100,000 and one cartridge of 4% Septocaine® with epinephrine, 1:100,000, NADR.  Profound anesthesia was acquired.

The PMMA temporary was removed, and the remaining teeth were extracted atraumatically. BioPlugs were placed into the extraction sockets, and PMMA implant screw-retained prosthesis was secured onto the integrated implants. Postoperative instructions were given, and the patient was instructed to return to the clinic in 4 weeks for the final impression.

Figure 17: Stage 3 — healing abutments in place and Figure 18: Stage 3 — atraumatic extractions

Figure 19: Stage 3 — PMMA screw-retained to integrated implants occlusal view and Figure 20: Stage 3— PMMA screw-retained to integrated implant frontal view

Figure 21: Final radiograph of prosthesis; no cantilever or distal extension

Stage 4: prosthetic phase after 4 weeks of healing

The patient returned to the office, and the PMMA screw-retained temporary was removed. Impression copings were placed, and radiographs taken for confirmation of full engagement. Final implant level impressions were made with PVS material using a heavy- and light-body wash technique. The temporary was reinserted, and the access opening was filled with PVS material for easy retrieval. The patient was scheduled for final delivery in 4 weeks.

Figure 22: Final implant placements in key positions with adequate A-P spread and Figure 23: Final implant placements in key positions with adequate A-P spread

Figure 24: Final FP1 maxillary prosthesis frontal retracted view and Figure 25: Final FP1 maxillary prosthesis occulsal view

Final appointment

The temporary was removed, and the final prosthetic torqued to 30Ncm based on manufacturer. The final access openings were filled with Teflon tape, Bisco’s All-Bond Universal®, and VOCO GmbH composite, and the final occlusion was equilibrated. The postoperative instructions were given to the patient, along with a water flosser and oral hygiene instructions, and she was scheduled in 2 weeks for evaluation as well as her maintenance plan.

Figure 26: Final close-up lateral view and Figure 27: Final close-up facial view

Discussion

Of course, there are a myriad of treatment possibilities for the terminal dentition.⁹  When to institute treatment is a collaborative effort that involves the patient and the treating doctor. Prognostic understanding and educating the patient are vital to achieving predictable clinical outcomes. The aforementioned treatment was initiated prior to loss of anatomy, and the patient desired to have a more functional and esthetic outcome. Furthermore, without extensive breakdown, the need for advanced bone grafting procedures can be avoided, and the aforementioned “key” implant positions¹⁰ can be placed. Prosthetic-wise as clinicians, we can bypass cantilevers and large pontic spans,¹¹ resulting in less stress in implants due to tension being placed down the long axis of the implant rather than sheer forces. This allows for less crown height-to-implant height ratio, which creates less force on the implants. Consider this: Ovate pontic spaces with short spans are much more easily maintained due to crested bone architecture and are easier for the patients to preserve.

Conclusion

Predictable and reproducible creation of the FP1 prosthesis is an attainable treatment module when the plan is initiated prior to excessive anatomic loss. Through taking clinical digital photographs, 3D scans, radiographs, comprehensive records, impressions, and thorough clinical examinations to screen patient, the treatment can be tailored to the patient. Considering the patient’s desire for his/her clinical outcome and determining the most effective way to educate him/her on the treatment path will increase acceptance.  Although there are more clinical stages and patient visits, it has been the author’s experience that the patient’s expectations are met and often exceeded.