Complete arch oral implant treatment using photogrammetry was studied in 77 patients with 111 arches focusing on digitization of clinical records and optimization of the provisional. The aim of the study was to test the hypothesis that patient satisfaction with the provisional prosthesis during the first 4 months of care determined workflow efficiency and success. Digitization of 8 clinical records was done including centric relation, vertical dimension, esthetics, occlusion, inter-arch space, abutment selection, abutment capture, and soft tissue scan. These records were then used to manufacture the provisional prostheses. All 111 prostheses seated passively indicating accurate photogrammetry registration.
Key points
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The provisional prosthesis determines success or failure of digital workflow.
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Patient approval of the provisional prosthesis is the key step in digital workflow for complete arch implants.
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Eight records including centric relation, vertical dimension, esthetics, occlusion, inter arch space, abutment slection, abutment capture and soft tissue scan are digitized.
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Digitization allows for a single operator, such as an oral maxillofacial surgeon, to complete all neccessary steps including provisional delivery on the day of surgery.
Introduction
Photogrammetry is rapidly becoming the foundational digital technology for complete arch oral-implant-based restoration as performed by oral and maxillofacial surgeons and restorative dentists.
Although 2-operator care for the edentulous or the soon to be edentulous patient is common practice, meaning separate surgeon and separate restorative dentist, a scrupulous digital process opens a real possibility for single-operator care particularly through and including the provisional prosthesis. ,
The use of photogrammetry eliminates the need for a laboratory technician to be present on the day of surgery. Printing or milling of the interim prosthesis proceeds chairside.
Unguided, free-hand surgery, once thought to delay or add risk for accuracy and timely manufacture of a complete arch provisional prosthesis, is now acceptable if not preferred when using photogrammetry—the use of guided procedures, often unnecessary, time consuming, and redundant. ,
But, photogrammetry is new, with negligible market penetration and almost no reports in the literature. The purpose of this article is to report chairside findings up through the provisional phase, after which the interim prosthesis, being digitized, is replicated into final form. , ,
Reported here are early-care results of 111 complete arch patient treatments using photogrammetry. Various oral implants were used by 5 surgeons in 5 different clinics in the United States, over a period of 18 months. In this report, 8 separate clinical records are recorded to standardize fabrication of a complete arch prosthesis.
Treatment of edentulous or soon to be edentulous patients presents significant challenges for clinicians in meeting high patient expectation for esthetics, phonetics, form, and function. With the introduction of innovative digital technologies, the delivery of implant-born prosthetics is significantly advanced allowing for greater cost efficiency, improved workflow, and ease of treatment. , ,
Complete arch rehabilitation is generally accomplished by the use of 4 implants, the major advantage being the ability to bypass extensive bone grafting. This so called “all-on-4” satisfies esthetics and function at a reduced cost. Implant rehabilitation on 6 to 8 implants per arch is commonly found to be unaffordable. Therefore, the “graft-less” protocol of the all-on-4 is presently the most common treatment of the edentulous patient. ,
Less than 4 implants (all-on-3) are reserved for severe mandibular atrophy (Class D). ,
More than 4 implants are needed for patients who have not lost bone (Class A), have severe bruxism, poor bone quality, or for extreme maxillary atrophy where quad zygomatic and pterygoid implants are prescribed.
Minimally invasive implant dentistry adheres to a concept of preserving bone— os sustinere. With this concept, the surgeon “sustains” available biology as the lifeblood of the younger patient. Bone reduction and attendant gingival subtraction are, therefore, avoided in making an effort to restore the patient to orthoalveolar form.
Whether sustinere or ablation of the alveolus is selected, complete arch implant therapy remains a challenge often leading to prolonged treatment times with numerous clinical appointments, onerous cost, and unpredictable outcome. The surgical and restorative experience for complete arch care, therefore, remains one of over-complexity, general confusion, high stress, and economic uncertainty.
Surgeons sometimes decide to abandon complete arch care in their practices not because of the rigor of surgery but because of prosthetic debacle.
But why is the restorative phase so complex and problematic? What is the root cause of the problem and what is the solution?
The purpose of this article is to address how to avoid surgical/restorative complication up to placement of the interim prosthesis. We propose digitization of 8 clinical records as the solution to replace what in the past has been an analogue mess. The clinical goal, therefore, is to digitize each step of the treatment process to facilitate provisional restoration. Once these digital records are complete, the patient is classified as “certified.” This process standardizes a protocol in which the surgeon plays a significant role including establishing the postsurgical implant registration and soft tissue survey.
Photogrammetry is a relatively new technology implemented by clinicians who perform multi-implant rehabilitation. Two to 5 digital cameras take multiple simultaneous images at slightly different angles that precisely correlate abutment position within a software program. Photogrammetry is most useful for complete arch implants. Commercial photogrammetry cameras include chair mounted, extraoral hand-held, and an intraoral hand-held wand ( Fig. 1 ). The technology is constantly improving, now recently combined with scanning ( Fig. 2 ).
First-generation photogrammetry-employed scan bodies ( Fig. 3 A ) were later merged with an analogue soft tissue impression. Recent integration of photogrammetry and soft tissue scanning significantly advances dental technology by enabling a single device to perform both intraoral scanning and photogrammetry ( Fig. 3 B). This dual functionality enhances the efficiency of digital workflow facilitating preoperative scans to seamlessly align with the photogrammetric record. Capture of photogrammetric markers is converted into identifiable and recognizable scan bodies ( Fig. 4 ). This capability reduces potential for error, smooths and integrates digital workflow, and reduces time requirement.
By consolidating these processes into a single project file, workflow is simplified. This reduction in complexity and the need for fewer manual interventions decrease the likelihood of mistakes, thereby improving the accuracy and reliability of the final prosthetic design. Thus, streamlined workflow shortens prosthesis conversion, enhances productivity and efficiency within implantology practice. In sum, photogrammetry is the enabling technology leading to abbreviated treatment time, predictable clinical outcome, and optimized case economics.
Reported here are 77 patient treatments for 111 complete arch restorations where photogrammetry was used exclusively to capture abutment position. The study period was 18 months.
The study hypothesis was that patient response of acceptability of the provisional upon delivery is the governing principle in complete arch restoration. In other words, if the interim prosthesis is interpreted by the patient as esthetically and functionally faithful , the patient presumes that the final will be also thus positioning the clinical team for success.
The study therefore focused on provisional prosthetic outcome as the determinate of overall treatment time, number of restorative appointments, clinician and patient experience, effort needed when going from provisional to final restoration, and overall cost. The goal was to understand the exact data inputs required to predictably satisfy the patient.
The majority of problems in compete arch treatment are restorative related, and all restorative problems are rooted in provisional outcomes postsurgery. The surgeon may perform a well-done surgery, but with poor prosthetic execution, the surgical result is “undone.” Therefore, for a predictable fabrication of an optimal provisional, the surgeon must participate.
There are many mostly analogue procedures presently used to fabricate a provisional including denture conversion, prefabricated prosthetic pick-up (guided surgery protocol), and guide stent conversion to provisional. Digital fabrication methods include intraoral scanning, photogrammetry, printing, and milling. Regardless of the fabrication method, it is the outcome of the provisional that matters. More importantly, it is the response of the patient to the provisional at delivery that ultimately counts ( Fig. 5 —green path).
Patient acceptance of the provisional sets up the clinical team at the 4-month integration check appointment on a predictable path to final restoration.
When the provisional is rejected by the patient at delivery this forecasts an unpredictable path to the definitive restoration (see Fig. 5 —red path).
Patient acceptance or rejection of the provisional is the sole metric, determining the restorative path forward. The task then is to discover how best to consistently fabricate an optimal provisional prosthesis ( Box 1 ).
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Black: The number of patients who accepted the outcome of the provisional. The only item lacking for final restoration is an updated soft tissue scan.
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Blue: The number of patients who accepted the provisional outcome but had complications during healing which required refabrication of the prosthesis. Complications included breaks, delamination of gingival composite, or wrong screw design.
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Green: Two patients accepted provisional outcome but had implant failures. This required additional work including new implant placement, new photogrammetry scans, new milled prosthesis, and additional chair time for delivery.
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Yellow: These were patients in which occlusion needed adjustment such as correction of anterior open bite.
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Red: These were patients who rejected the provisional. These patients required course correction which required additional resources.
The Digital Solution
There are 8 objective clinical inputs required in digital format to predictable fabricate an optimal prosthesis for an edentulous patient ( Fig. 6 ). These include centric relation, vertical dimension, esthetics, and occlusion—these 4 are commonly done by the restorative dentist. Accomplished by the surgeon are bone reduction, abutment selection, abutment capture, and soft tissue scan ( Figs. 7 and 8 ).
Missing any one of the 8 records results in deficiency in prosthetic outcome and prosthetic deficiency leads to patient dissatisfaction. Each deficiency requires correction, and corrections require additional time, cost, work, and skill. It is, therefore, impossible to fabricate an optimal complete arch implant prosthesis without these records.
The surgeon, being part of the prosthetic team performs half of the prosthetic records, but more importantly than that, the surgical team functions to cross-check that all 8 records have been digitized prior to milling or printing the prosthesis chairside in the surgeon’s office. Without surgeon engagement in prosthetic manufacture, the surgical effort risks compromise.
The 8 Universal Records
Centric relation
When restoring an edentulous patient, the only repeatable and stable position to relate the movable mandible to the fixed maxilla is to first position the condyles into the fossae, termed as centric relation ( Fig. 9 ). With the condyles seated superiorly and anteriorly in the fossae, the mandible can now hinge and rotate on the y -axis. Centric relation (CR) is the foundational position to establish and predictably restore an edentulous patient. Everything moving forward from this point is secondary to it.
Surgeons recognize this important concept as accomplished during Le Fort I osteotomy surgery with autorotation of the mandible by holding the mandible into centric position.
Vertical dimension
Vertical dimension of occlusion (VDO) is correctly established when the condyles are in CR. VDO is found by autorotating the mandible until the VDO is determined to be correct. VDO in prosthetics, as in orthognathic surgery, does not have an objective end point and deciding what is the correct vertical for the patient can be intuitive. Multiple factors need to be evaluated which include esthetics, phonetics, and measurement of facial thirds. Once established, the teeth can then be correctly positioned for esthetic tooth-show and occlusion determined within this spacial dimension ( Fig. 10 ). ,
Esthetics and occlusion
After CR and VDO are established, maxillary esthetics is finalized. When optimizing esthetics, important considerations include incisal edge position, midline, occlusal plane, arch form, tooth mold/shade, gingival shade, and gingival architecture. Once maxillary esthetics have been optimized, mandibular teeth are digitally coupled to maxillary teeth for ideal occlusion with the mandibular occlusal plane extending two-thirds the way up the retromolar pad to avoid excessive mandibular incisor display.
Soft tissue
The soft tissue record is done by the surgeon after wound closure using scanning technology. It is important to capture sufficient mucosal architecture in order to properly design the intaglio of the prosthesis, which is made slightly convex, is highly polished, and with a nearly flat emergence profile reflective of creation of the bone shelf ( Fig. 11 ).
Bone reduction
Bone reduction is essential in fixed denture treatment plans in order to have sufficient inter-arch space for prosthetic material thickness and strength ( Fig. 12 ). It is the surgeon’s responsibility to ensure adequate hard tissue removal to create the all-on-4 shelf. A clearance of 15 mm from incisal edge to the bone shelf is needed for both arches. This often requires removal of several vertical millimeters of healthy bone ( Fig. 13 ). It is important for bone reduction to be sufficient for both anterior and posterior segments which can be difficult to do with nerve and sinus proximity. Insufficient reduction requires reentry surgery and remake of the prosthesis.
Class A bone availability, especially as found in younger patients, requires no bone reduction and is the preferred method for complete arch implant rehabilitation, usually using 6 to 8 implants for a segmented bridge restoration. ,
Abutment selection
Abutment selection prescribed by planning software ( Fig. 14 ) is done by the surgeon, the goal being to position the screw access holes lingual to the buccal surface of the teeth within the correct arch form. Improper abutment selection and placement can lead to screw access holes in the line of sight and other problems such as increased prosthetic cantilever, excessive material thickness, poor hygiene access, and nonideal emergence profile ( Fig. 15 A ).
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