Treatment of the fully edentulous or the terminal dentition patient today with the immediate load protocols has become accepted globally with predictable outcomes. Reconstruction of patients with full arch prosthesis is an advanced procedure. In order to facilitate the planning, the execution of the surgery/immediate loading as well as the fabrication of the final prosthesis, the Digital workflow is adopted by most teams. However, the treatment planning of the existing fully edentulous or the terminal dentition patient requires a comprehensive knowledge of the fundamental prosthetic as well as the surgical principles.
Key points
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Contemporary implant practices incorporate the digital workflow in their treatment planning.
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Fundamental understanding of prosthetic and surgical principles is essential before adopting the digital workflow.
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Three alternative techniques for the fabrication of the immediate load provisional allow the clinician to identify the best technique for their individual patients.
Introduction
This article reviews a systematic treatment planning protocol for the fully edentulous as well as the terminal dentition patient. Case presentations are introduced with the opportunity for the reader to compare and contrast the 3 different techniques available for the fabrication of the immediate load, fixed provisional following the placement of the implants. Once the pros and cons of the various techniques are clear to the implant team, the adoption of one or all of the 3 techniques presented in this article to better fit their patient’s treatment needs and protocol.
Potential candidates for implant restoration of the maxilla present with either failing remaining maxillary dentition, also referred to as “terminal dentition,” or with existing edentulous maxillae with various degrees of resorption. Many of these patients seek a fixed restoration to replace their missing teeth. To provide a fixed prosthesis, traditionally, multiple surgical approaches, including procedures involving grafting with delayed implant placement is the protocol to re-establish form and function for this group of patients. However, reluctance for acceptance of the treatment exists as during the various stages of the treatment, this group of patients had to function with a complete removable prosthesis, which generally was poor fitting with minimal patient satisfaction. To increase patients’ acceptance of full arch treatment plans, the placement of implants with simultaneous immediate loading is the widely accepted treatment protocol today. Therefore, it is important to recognize that among implant teams globally, the graft-less approach with immediate loading has been thoroughly documented as a predictable outcome.
In the contemporary implant practices, treatment of all existing edentulous patients as well as patients with terminal dentition using the immediate loading protocol is acceptable as long as initial stability of the implants is achieved at the time of placement. Reduction in the number of treatments and the overall treatment time as well as significant reduction in the cost of reconstruction using the graft-less concept is appealing to many patients. For patients who present with terminal dentition as well as for edentulous patients who are using removable prosthesis, an immediate load protocol allows for a fixed solution on the day of surgery. A fixed implant-supported provisional prosthesis is not only more comfortable for patients following the graft-less treatment protocol but also allows them to assess both function and esthetics and thoroughly evaluate and communicate any changes desired prior to fabrication of the definitive prosthesis.
The contemporary protocols available for the graft-less concept include the use of tilted or zygomatic implants to allow the surgeon to establish adequate posterior support and thereby increasing the anteroposterior (AP)-distribution of the implants along the arch length for a fixed prosthesis. Using tilted or zygoma implants allows for establishing adequate AP distribution of implants with reduction or elimination of the cantilever on the immediate load prosthesis distal to the terminal implant.
Clinicians must appreciate that the predictable success of these cases requires the complete understanding and execution of fundamental prosthetic as well as surgical principles in the treatment planning of these groups of patients. Beginning with the “end in mind” approach in treatment planning is essential for a favorable outcome. To achieve this goal, adopting a systematic treatment planning protocol by the implant team is essential for the evaluation of the edentulous patient as well as patients with terminal dentition. The following section provides the implant team with a protocol to follow for formulating the appropriate treatment plan.
Prosthetic and Surgical Evaluation
Prosthetic evaluation of patients with terminal dentition and/or existing edentulism of their maxilla or mandible is complicated by the fact that patients may present with loss of clinical crowns only (ie, tooth-only defect) or the loss of clinical crowns as well as associated hard and soft tissues (ie, a composite defect; Fig. 1 ).
A systematic pretreatment approach allows for better communication among the members of the implant team to determine the nature of the defect, tooth only versus composite defect, to determine the type of final prosthesis needed. The maxilla compared to the mandible is unique as the consideration of Phonetics , and the Transition line , the junction between the intaglio of the prosthesis and the patient’s alveolar soft tissue is critical. When using the Bedrossian systematic treatment planning protocol, 3 factors in the examination process can be key determinants for the successful treatment outcome of the completely edentulous maxilla with a fixed restoration.
These factors are
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Diagnosis: the presence or absence of a composite defect
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Determining the type of the definitive prosthesis
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Visibility of the transition line; evaluation for an esthetic outcome
Once the definitive design of the final prosthesis is determined, the available alveolar bone of the edentulous maxilla, the maxillary zones, determines the surgical protocol for establishing posterior support using axial, tilted, or zygoma implants to support a fixed implant-supported prosthesis.
Evaluation of these 4 factors is not intended to be a substitute for thorough diagnosis and development of a treatment plan. However, such evaluation can provide differential diagnosis information specific to the esthetic, phonetics, and biomechanical requirements of fixed, implant-supported maxillary restorations.
The surgical evaluation
As discussed earlier, the surgical treatment of the edentulous maxilla is complicated by the lack of available boney volume for the placement of implants in the posterior maxilla to establish adequate AP distribution for the support of a fixed prosthesis.
Lack of vertical boney volume in the second premolar and or the first molar area, as well as the anterior extension of the anterior wall of the maxillary sinuses, limits the axial placement of implants. In order to systematically approach the preliminary surgical evaluation of patients needing maxillary implants placed along the arch form, the maxilla is divided into 3 zones, referred to as the Bedrossian classification ( Fig. 2 A, B ).
If all zones of the maxilla are available, 4 to 6 axial implants are placed. If there is alveolar boney deficiency in zone 3, tilted implants are placed. If alveolar boney deficiency extends from the molars to the bicuspid region, 2 to 4 premaxillary implants and zygoma implants to establish posterior support is considered. Finally, in the absence of maxillary alveolar bone, lack of zones 1, 2, and 3, the Quad-zygoma concept is adopted as demonstrated in Fig. 3 .
Upon completion of the treatment planning, the surgical phase is initiated and completed either by free hand (analog technique) or by guided surgery as in the stackable-guided surgical protocols available today. If an insertion torque of 35 to 40 Ncm is achieved intraoperatively of each implant placed, immediate loading of the implants is acceptable.
As a part of the treatment planning process, the implant team plans the protocol for the fabrication of the immediate load provisional prosthesis. There are 3 methods for fabrication and delivery of an implant-supported immediate load prosthesis as described in the following list:
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Traditional conversion of a digitally fabricated immediate complete denture
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Stackable or sequential guided systems
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Digital workflow utilizing photogrammetry and 3 dimensional (3D) printing
The purpose of this article is to compare the traditional conversion of a full denture to an immediate load provisional process to alternative techniques available today. The 2 alternative/contemporary techniques available are (1) the prefabricated provisional made using the stackable guide protocols and (2) using photogrammetry immediately upon completion of the surgery to fabricate the immediate load prosthesis. It is also prudent to review the materials used for the fabrication of the various immediate load provisional prosthesis, which is covered in the following section.
Materials used for fabrication of the provisional
The design, fabrication methods, and materials used for the immediate denture used for the interim conversion prosthesis have evolved over the years. Traditional techniques for immediate loading protocols with fixed interim prostheses include the use of a conventional denture, fabricated by way of heat-activated polymethylmethacrylate (PMMA) or chemically activated PMMA through a pack-and-press, pour, or injection mold technique. Following the placement of the implants, the conventional denture is then indexed and converted into an interim fixed prosthesis and utilized for the duration of the osseointegration period. During the osseointegration period, prosthetic complications may occur including fracture of the acrylic resin, delamination of the acrylic resin from the temporary abutment, or delamination of denture teeth from the acrylic base. Reasons for these complications can arise from improper treatment planning leading to insufficient prosthetic space, internal voids, or mechanical properties of the acrylic resin fabricated, improper bonding of the acrylic resin to the temporary abutments, or noncompliance for dietary and functional restrictions by the patient. Nevertheless, converting traditionally fabricated dentures have had great success if planned and executed by the surgical and restorative team.
While conventional dentures have been effective over the past several decades, the advantages of contemporary complete dentures manufactured using computer-aided design and computer-aided manufacturing (CAD/CAM) have been shown to be more advantageous.
The benefits of CAD/CAM-designed dentures include higher flexural strength, and fracture toughness due to the high density of the polymers used has gained popularity in immediate loading protocols. It is important to point out that 2 techniques are available for the manufacturing of a CAD/CAM denture, subtractive manufacturing and additive printing. Subtractive manufacturing by way of milling a prosthesis out of a prepolymerized disc rather than additive printing has shown its improved mechanical properties, such as increased flexural strength, hardness, and biocompatibility. , It has been reported that these enhanced properties of the CAD/CAM denture bases have therefore limited the potential prosthetic complications and making them a desirable material choice for conversion during immediate loading workflow.
With the advantages experienced in clinical practice, CAD/CAM materials have also been used for contemporary digital workflows (DWFs). The stackable systems , 3D printing, or milling of an interim implant-supported prosthesis is one of the commonly adopted protocols when using the DWFs. , The use of the DWFs with prosthetically driven surgical implant planning using CAD software and guides aims to improve the accuracy of implant placement. Various stackable guides have been developed with innovative designs for improved stability, retention, and conversion of the interim immediate load prosthesis, providing predictability and efficiency as an alternative approach to traditional conversion techniques. , Alternatively, the use of photogrammetry and 3D printing the interim prosthesis as the immediate load material is currently gaining popularity. This DWF technique requires a keen understanding of data acquisition, alignment of the standard tessellation language (STL) files in CAD software, and compliance with printing parameters and postprocessing manufacturing methods for an accurate fabrication of the immediate load prosthesis.
The following 2 cases highlight the use of the analog , stackable , and the photogrammetry protocols for the fabrication of full arch immediate load prosthesis. The pros and cons of each technique are presented at the end of this article allowing clinicians to adopt the protocol most suitable for their patients and their team.
Case 1: Traditional Conversion Versus Digital Photogrammetry Conversion
A 65 year old man with terminal maxillary dentition: Clinical and radiographic examinations were consistent with stage 3, grade B periodontal disease, as well as a collapsed vertical dimension of occlusion (VDO; Fig. 4 A, B ). The cone beam computed tomography (CBCT) confirms the generalized loss of alveolar support complementing the periodontal findings and diagnosis of terminal dentition. Following the Bedrossian treatment planning protocol, the patient was diagnosed with a composite defect of the maxillary dentoalveolar complex. After removal of the remaining teeth and alveoloplasty, a fixed partial dental prosthesis 3 (FP3) maxillary fixed implant supported hybrid would be indicated. Evaluation of the patient’s transition line was consistent with a long upper lip with no display of his premaxillary soft tissues (see Fig. 4 A, B). The Panorex, 2D radiographic evaluation allows for the identification of the absence or the presence of residual alveolar bone in the various maxillary zones ( Fig. 5 ).
Evaluation of the various zones was consistent with the following findings and is represented in Fig. 5 .
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Absence of bone in the right zones 3
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ZAGA 1 anatomy of maxillary right zygomatic contour
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Presence of bone in premaxilla zones 1
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Presence of bone in the left zones 2
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Presence of bone in the left zones 3
The 3 D radiographic examination was consistent with ZAGA 1 anatomy for the placement of the zygoma implant allowing quad-cortical stabilization of the zygoma implant. Areas 7, 11, and 14 demonstrated adequate boney volume for the placement of axial implants ( Fig. 6 A–E ).
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