April 12, 2021
by Chad C. Duplantis, DDS, FAGD
The anterior single unit implant can present a challenging dilemma to both the restorative dentist and the surgeon. Several factors may present that can adversely affect the final restorative outcome of cases such as these. Appropriate planning and execution are crucial for a pleasing result to both the patient and clinical team. Digital tools have greatly improved the capabilities of the clinicians in planning, placing, and restoring of implants in these situations. Throughout this article, we will look at some of the tools being used today, and present a case utilizing several digital aids to achieve a pleasing result.
Not many years ago, multiple analog methods and procedures were used to plan, place, and restore implants. Traditional impressions and two-dimensional panoramic or periapical radiographs were utilized to provide a preliminary surgical and prosthetic plan. Although these methods were used with success over the years, they lacked critical data in the planning processes. Traditional impressions and stone models are a great diagnostic tool; however, many variables exist that can affect the dimensional accuracy.1 A distorted diagnostic stone model can adversely affect the outcome of the placement and ultimately the restoration of an implant. Periapical radiographs have been excellent diagnostic tools in dentistry for many years. These are also necessary and beneficial for the single unit implant. They can help determine the mesiodistal and vertical dimensions of the proposed site, help visualize any contradicting pathology, and provide an idea of the bone quality. With this radiograph being two-dimensional, the main limitation is that there is no information provided regarding the bone volume.2,3 Panoramic radiographs are also a useful diagnostic tool, but they too have their downfalls. These radiographs capture a large amount of data. Panoramic radiographs are beneficial for the identifying contradicting pathology, the general vicinity of anatomical landmarks, and the potential suitability of a proposed implant site. This is once again a two-dimensional image, and the distortion potential of this radiograph limits the clinical team in an accurate evaluation.3,4
The aforementioned tools and methods have provided clinicians with successful outcomes for many years in implant placement and restorative procedures.5 Although the success rate was high with the analog methods, the process required much training and an analytical mind.
Over the past several years, digital aids have greatly transformed the landscape of dentistry in many ways. Three digital tools that have had a profound impact on implant dentistry are intraoral scanners, cone-beam computed tomography (CBCT) systems, and implant planning software.
In addition to the digital tools, there must be a patient centric collaboration between the surgeon, the restorative dentist and the laboratory. The communication amongst this team must be constant and effective. This collaboration creates a pyramid of implant success. In this article, we will examine each of these tools. A case will be presented utilized this digital technology and teamwork to create a successful outcome for the patient.
Chairside indirect dentistry affords clinicians numerous choices to treat patients efficiently and effectively. The first chairside indirect restoration was placed in 1985 by Dr. Werner H. Mörmann in Zurich, Switzerland.6 The significance of this is that in order to obtain the image of the preparation, an intraoral scanner was used. Intraoral scanners have been in use un dentistry for many years. Although the original intent was that these scanners were only part of a complete system designed to produce indirect restorations the same day, the technology has greatly advanced over the years.
Intraoral scanners are devices that utilize technology to capture optical impressions in dentistry. These impressions may be utilized in a similar manner as a traditional analog impression and resultant stone model. Laser or structured light serves as the source projected onto the desired surface to be captured or impressed. The proprietary software of the particular scanner then reconstructs the image into a 3D file, or .stl file. This file has numerous uses in dentistry.7
According to Dr. Francesco G. Mangano, et. al in a great review entitled “Intraoral scanners in dentistry: A review of the current literature”, intraoral scanners offer several advantages to the clinician:
As far as accuracy is concerned, several studies have found that optical impressions are accurate. These devices can be used effectively for diagnostic, restorative and implant purposes. The accuracy does falter, however, when scanning longer spans (greater than 4 teeth) and edentulous arches.5,7-9 It is for this reason that the author still recommends traditional analog impressions for full-arch implant impressions.
Cone-Beam Computed Tomography (CBCT)
Cone-beam computed tomography (CBCT) has been in use in the United States since the early 2000s.10 The use is growing, and it is quickly changing the way that we practice dentistry, dental surgery, and oral and maxillofacial radiology. These systems are similar to the devices used in medicine for years in that they produce a 3D image of the head and neck region. The difference is that the CBCT rotates around the patient utilizing a cone-shaped X-Ray beam. Although the radiation exposure differs amongst manufacturers of CBCT devices, they do offer a substantially lower radiation exposure than conventional medical CT devices of ≤ 75%.3,11
CBCT provides detailed volumetric data and allows us to visualize any pathology or deviations in normal anatomy of the dentoalveolar and head and neck regions. The mesiodistal, buccolingual, and occlusogingival aspects of the alveolus can be assessed readily using this imaging device. This data is crucial in implant planning, and can be used for surgical and prosthetic planning as well. 11 The analysis of the data has reduced implant failures through accurate and detailed planning.12
CBCT provides an added level of security upon implant placement. In fact, in 2012, the American Academy of Oral and Maxillofacial Radiology recommended that “some form of cross-sectional tomographic images be used to treatment plan dental implant cases.”13 It is from this statement alone that one can deduce that CBCT imaging is quickly becoming, or has become, the standard of care in implant planning.
Implant Planning Software
Having discussed intraoral scanners and CBCT radiography, it is important to understand how to properly integrate these data sets. Implant planning software enables the clinician to incorporate the .dcm files from the CBCT and the .stl files from the intraoral scanner into a collaborative platform.
The software is deemed a prosthetic-driven approach to implant placement. The visualization of the intraoral scan superimposed over the CBCT allows for a predictable approach to implant placement and restoration. Throughout this approach, the implant is placed virtually. The libraries of the different softwares available are vast in terms of implant brands and components. Once the implant is placed virtually, a guide can be created through the software and printed using a 3D printer. Temporaries with appropriate components can be fabricated digitally as well. Guides fabricated for this surgery can be tooth-borne, tissue-borne, or a combination of the two. It has been found that tooth-borne guides are more accurate than the tissue-borne guides.14
This approach allows for a comprehensive evaluation of the dentoalveolar complex and eliminates the majority of the guesswork. This software allows the surgeon, the dentist, and the laboratory to work off of a single plan. This software can be owned individually by either the dentist, surgeon, or laboratory. Additionally, there are several services that will allow the team to collaborate virtually for a fee and plan on a case-by-case basis rather than owning the software. Although a guide may not be indicated for all cases, this approach is beneficial for patients receiving multiple implants, if bone quality is questionable, or if there is little room for error in placement.15
A case report
This patient is a 40-year-old male that was referred to our office following a visit with the periodontist, Scott Bedichek, DDS, MS. The initial consult in our practice was for a replacement of tooth #9 with an implant restoration, with the implant to be placed by the referring periodontist. The periodontist had been monitoring this patient on regular examination for some time. Tooth #9 had a zirconia restoration placed approximately 5 years prior that was bothersome to the patient, aesthetically and functionally. The patient states that the crown was not aesthetically appealing, it had been adjusted on numerous occasions, and had become increasingly mobile. There was a perforation in the lingual aspect from the numerous adjustments. The patient had also stated that the crown had “come off” a few times and that endodontic therapy had been performed twice prior. Following discussion, the patient was seeking a new dentist and had decided that he wanted an implant rather than potentially have more problems with this tooth. Initial photos can be seen in Fig. 1.
Prior to initiating any implant therapy, it is vital to assess the occlusion. An intraoral scan is one of many ways to address the occlusion and note any potentially problematic areas. In an analysis of his occlusion, the molar relationship was deemed to be a Class I molar relationship. The main orthodontic concern was his malocclusion which was creating traumatic occlusion in the anterior region. It was clear that tooth #24 and tooth #9 were in a detrimental occlusal relationship. The patient was not interested in full orthodontics; therefore, limited orthodontics was recommended to develop a more stable occlusal scheme in the anterior region.
At the time, we took initial scans using our 3M True Definition Scanner (3M Oral Care, St. Paul, MN) and sent them to the MTM Clear Aligner (Dentsply Sirona, York,PA) portal. Our goals in orthodontic therapy were to improve upon the anterior alignment while maintaining the posterior occlusion. Without correction of the malocclusion, the implant would be subject to failure, or the crown would have to be placed in a position that would affect the final esthetic outcome adversely. The patient went through 15 weeks of clear aligner orthodontic therapy and subsequently 3 months of retention. Post-orthodontic photos can be seen in Fig. 2.
Following a period of retention, the patient was then scanned again utilizing the iTero Element intraoral scanner. The radiographic assessment at that time was performed via CBCT. These two data sets were uploaded into a portal utilizing Implant Concierge (San Antonio, TX, www.implantconcierge.com), which utilized coDiagnostiX® (Dental Wings Inc., Montreal, QC) implant planning software. Through a virtual consultation, the surgeon, restorative dentist, laboratory were all able to collaborate and plan the surgical and restorative approach. This collaboration is crucial to success in pre-prosthetic planning for guided implant surgery. In this case, a tooth-borne guide was fabricated, and was custom fabricated to the particular implant (Straumann RC bone level tapered, 4.1 x 14 mm). A temporary was also fabricated digitally for placement at the time of surgery. Along with the guide, a surgical plan was sent that provides a step-by-step guide for the surgeon to minimize the potential for any complications during surgery. The surgical planning images can be seen in Fig. 3.
One might ask why a guide was chosen in this case, seeing as it was an immediate extraction. Immediate extractions offer the surgeon an opportunity to place the implant in the extraction site. In some cases this can be desirable; however, it can be seen from the planning images (refer to images) that the angulation of the root would have led to a less than ideal position of the implant. The planned approach enabled us to place the implant in a more ideal position that would lead to a better emergence profile and better restorative outcome. Following the extraction site would have led to similar occlusal issues as before or a less than ideal emergence profile.
The implant was placed with ease through use of the guide and plan. (Fig 4) Upon placement, it is vital to verify initial stability in order to ‘load’ the implant, or immediately provisionalize. Three key components improve our chances of immediate provisionalization: 1. An osteoconductive, tapered, grooved implant of at least 10mm in length.2 The bone quality and quantity, and 3. Initial stability of the implant (≥ 35 Ncm torque) at placement.16 This particular implant possessed all of those characteristics, and upon placement the torque was measured to be greater than 40 NCm. The temporary was placed immediately following the surgical placement of the implant. It can be clearly seen that the temporary (although slightly off in value) was ideal in emergence profile and position. (Fig 5) This was entirely possible through the use of a guide and proper pre-prosthetic planning.
Following surgery, impression was taken in a closed-tray analog manner using a Straumann transfer coping and Honigum light and heavy body impression material (DMG America, Ridgefield Park, New Jersey). Although this impression could have been taken digitally, the author felt that an analog impression would allow for greater tissue reproduction on this single unit case.
The restoration was fabricated Alexander J. O’Ryan, CDT (North Richland Hills, TX) using a Straumann ti-base abutment with a custom zirconia coping (Fig. 6) torqued to 35 Ncm. The final restoration was fabricated using lithium discilicate (Emax, Ivoclar Vivadent, Amherst, NY), and was fabricated to be cement-retained. The shading was A2 at the gingival quarter, A1 to A0.5 blend for the body. The gingival tissue was slightly irritated upon insertion. The final restoration can be seen in Fig. 7. The patient has been seen on numerous occasions in recall, and the 1.5 year follow up images can be seen in Figs. 9-11. It can be seen that the gingival health has been restored and there has been no visible recession. The final occlusal scheme can be seen in the scan depicted in Fig. 12. Appropriate planning played a crucial role in the successful outcome of this case.
In dentistry, clinicians face many challenges that can negatively impact the outcome of treatment if not properly addressed from the start. The single unit implant case can be one of those challenges. Although it may be possible to place an implant immediately in an extraction site, proper attention must be placed on the presentation utilizing the tools available. Digital tools have made our decision process much more methodical, and our results can be improved by using the tools available to us. A motto to practice by is “Proper planning prevents poor performance.” Additionally, a team approach is critical for success in these somewhat challenging cases.
Oral Health welcomes this original article.
Acknowledgements: The author would like to acknowledge Scott Bedichek, DDS, MS, Periodontist, Keller, TX for his role in this surgery. Dr. Bedichek was involved in all planning and surgical aspects pertaining to this case. The author would also like to acknowledge Alexander J. O’Ryan, CDT, North Richland Hills, TX for his lab expertise and in creating the final restoration. The restorative outcome of this case would not be possible without the teamwork of the clinicians and lab technicians.
About the Author
Dr. Duplantis received his D.D.S. from UTHSC San Antonio in 1999 and completed an Advanced Education in General Dentistry program at Baylor College of Dentistry in 2000. He maintains a small group private practice in Fort Worth, TX, focusing on aesthetic and restorative dentistry. As a member of Catapult Education Speaker’s Bureau, Dr. Duplantis is an author, a lecturer, and a key opinion leader in dentistry. His interests are digital, implant, and restorative dentistry.