Arun Garg, Gregori Kurtzman and Niloufar Rezakhani look at the potential problems when placing an implant into a single or double site.
Introduction
Partially edentulous arches are the most frequently treated cases with implants in the average dental practice. Patients lose teeth for a variety of causes. These include periodontal bone loss and endodontic failures. Also, non-restorability of a tooth that may be related to caries or trauma.
Free-hand or guided implant placement
Implants can be placed free-hand or guided. Free-hand placement has potential for a number of errors that can make restoration challenging. It can damage the adjacent teeth or create spacing issues that may lead to periodontal problems over time. The alternative has been guided placement typically with a lab fabricated guide. These lab fabricated guides range from simple where in the lab sets denture teeth in the space and constructs an acrylic guide with a hole in the centre of the tooth. This guides the pilot drill to ensure proper spacing and orientation.
Other alternatives to this involve drilling a pilot hole in the study model. This is followed by inserting a pin and a guide sleeve over this and fabricating an acrylic surgical stent. This type stent can be used to only guide the pilot drill. Or for all drills to be used to create the osteotomy. More complex guides are possible utilizing CBCT scans, virtual implant placement in software (either performed by the practitioner or lab during planning) and a CAD/CAM milled guide based on that virtual placement. These CAD/CAM guides have switchable metal sleeves that allow guidance of all osteotomy drills that will be used during the surgery.
Issues and potential problems
Another issue with guides is fabrication time to allow the lab or service to construct the guide. Which means in simple cases there is a delay of usually two weeks before implant surgery can be performed to place implants into that partially edentulous space.
But, are these type guides necessary when only placing a single implant bounded by natural teeth (or restored implants)? Or a space that will accommodate two adjacent implants that has teeth mesial and distal to the edentulous space? If we understand what may go wrong in placement of implants in these two situations we can simplify the process of surgical placement.
Potential problems when placing an implant into a single or double site include; placement too buccal/lingual, leaving insufficient space between the implant and adjacent tooth or between implants being placed next to each other. Free-hand placement may lead to these complications. This can make restoration challenging especially in the aesthetic zone.
An implant placed too buccal/facial often does not blend well with the adjacent teeth and complicates the lab technicians work creating an abutment and crown to restore that implant. Placement too lingual is often less complicating to the desired aesthetic results. Orientation in the mesial-distal dimension may yield complications more related to perio than aesthetics.
Should free-hand placement be avoided?
When insufficient space is provided between the implant and adjacent tooth, the papilla is often lost either initially or over time leading to bone loss. This may be challenging to some patients to keep clean. It can also complicate the lab fabrication. This is due to insufficient space to accommodate the minimal thickness of the abutment and overlaying crown.
A screw retained crown may solve this dilemma. But it may not always be applicable clinically for that site and patient situation. Additionally, when the implant is not centred in the space and placed too close to the adjacent tooth on one side, this leaves a wider space on the other proximal surface leading to emergence profile issues and the consequential food trap under the proximal contact.
So, free-hand placement should be avoided in most practitioners hands. This avoids those potential complications. But, is there a simpler solution?
Guided implant surgery for partially edentulous spaces, a simplified approach
A kit has been developed that eliminates the problems when placing single or two adjacent implants when the space is bounded by teeth. The IVIS (Implant vision implant system) Implant Guidance System (Mediquip Implant Supplies, Jupiter, FL) provides guide tabs and pins. This allows proper orientation in the buccal-lingual and mesial-distal directions when creating an osteotomy (Figure 1)
The kit provides guidance tabs to accommodate implant placement of 3mm, standard diameter (SD, 3.3-3.6mm), regular diameter (RD, 3.75-4.3mm) and wide diameter (WD, 5.0-5.5mm).
(Figure 2) Each guidance tab is designed for either a single implant placement (front of tab) or two adjacent implants being placed (back of tab) with lateral wings to orient the implant osteotomy based on the cervical of the adjacent teeth. Additionally, a guidance tab is provided for narrow sites that may present at a maxillary lateral.
Additionally, it can be used for mandibular incisor placement requiring either a narrow diameter implant or mini implant due to available mesial-distal space present. (Figure 2*) The kit contains a handle to hold the guidance tab during surgery, permitting use in all areas of the arch.
Different types of pins
(Figure 3) When utilizing the tab for single implant placement, spacing of 2mm from each adjacent tooth is designed for ideal placement from the adjacent tooth. The double implant portion of the guidance tab, also sets spacing of 2mm from the adjacent tooth and an ideal 3mm between implants.
Guidance pins are in the kit in two forms. It allows one end to be used in the site following pilot hole creation in the site. The other end is used following use of wider osteotomy drills. The pins are colour coded similarly to the guidance tabs. (Figure 4) One set of pins (Measuring Pin) has horizontal blades to verify spacing following pilot drill use with the guidance tab.
The blades measure 2mm (to verify space to adjacent tooth). 3mm (to verify space between implants) and a longer notched tab to create a pilot hole when there is no distal tooth to use the guidance tab with. The other set of pins (Parallel Pin) can be placed into the 2nd pilot osteotomy. This verifies parallelism with the Measuring Pin. Following pilot hole creation a radiograph can be taken with the guidance pins in place. This verifies spacing to adjacent teeth, anatomical structures and parallelism to adjacent teeth.
Single implant guided placement
A guidance tab is tried into the edentulous space. This is so that the front portion of the tab fits into the space with little mesial-distal sliding. Also, that the wings are contacting the cervical of the adjacent teeth. (Figure 5) Should the tab be able to slide mesially and distally, the next size guidance tab is tried to verify if this fits the edentulous space better with less lateral movement possible.
A pilot drill is introduced through the hole in the guidance tab. This parallels the drill with the long axis of the adjacent teeth. (Figure 6) It is recommended that the pilot drill be taken to half the planned depth. A Parallel Pin should be placed and a radiograph taken to verify orientation to adjacent teeth and anatomical structures. Following confirmation, the guidance tab is reinserted and the pilot drill is taken to the planned depth. The osteotomy is completed with wider drills without the guidance tab intraorally. The system may be used in the anterior (Figure 7) or posterior (Figure 8) to guide implant placement.
Double adjacent implant guided placement
As with use of the guidance tabs for single implant placement, when using them for two adjacent implants the process to start is similar. A guidance tab (bottom portion) is selected to fit into the edentulous space that has minimal mesial-distal movement when inserted. (Figure 9) The guide tab is utilized to initiate the distal osteotomy with the pilot drill to half the planned depth (Figure 10). Then the mesial osteotomy is performed in an identical manner (Figure 11).
A winged Measuring Pin matching the planned implant diameter is inserted into the mesial hole. It’s rotated until the 2mm wing contacts the middle of the proximal of the adjacent tooth (Figure 12). A radiograph may be taken at this point to verify orientation if desired (Figure 13).
The notched wing is rotated to the second site. The pilot drill paralleled to the pin to complete depth of the drill using the notch as orientation point. (Figure 14). A guide pin of the planned implant diameter is inserted into the distal site. The 2mm or 3mm horizontal tab on the mesial pin is rotated. This contacts the distal guide pin to verify spacing of the parallel guide pins. (Figure 15) Guide pins can be placed into the initial sites. A radiograph gets taken to confirm orientation and parallelism of the implants before proceeding.
Digital osteomy
The distal osteotomy can be completed utilizing the mesial pin for parallelism. The wider end of the pin is then placed into the distal osteotomy. The mesial osteotomy completed using that pin for parallelism. The guidance system provides ideal spacing between the implants and adjacent teeth as well a between the implants. (Figures 16-17) As with the single implant portion of the tab, the double implant portion of the guidance tab may be used in the anterior or posterior to guide implant placement.
Conclusion
Guided implant placement does not require lab fabricated surgical guides. A simpler system can be achieved with the IVIS Implant Guidance System guide. When a single or two adjacent implants are being placed. The guidance tabs use the adjacent teeth to orient the initial osteotomy in both the mesial-distal and buccal-lingual dimensions. They create ideal spacing with the adjacent teeth or between implants. The same sequence for adjacent implant placement may be used when no distal tooth is present. The guide tab is utilized to create the mesial implant initial osteotomy. Then the pins as previously described utilized to orient and create the distal osteotomy. One key benefit of the guidance system is treatment may be accomplished at that visit. No delay is needed while waiting on fabrication of a custom surgical guide.
Dr Arun K Garg DDS
Dr Arun Garg is an internationally recognised dental educator and surgeon, who for more that 20 years served as a full-time professor of surgery in the department of Oral and Maxillofacial Surgery and as director of residency training at the University of Miami Leonard M Miller School of Medicine. he is considered one of the world’s preeminent authorities on bone biology, bone harvesting and bone grafting for dental implant surgery. A well-known lecturer and has authored nine published text books. Also, he has produced a dental implant marketing kit that has been translated into multiple languages and distributed worldwide. He can be reached at [email protected].
Dr Gregori M Kurtzman DDS
Dr Gregori Kurtzman works in a private general dental practice in Silver Spring, Maryland, USA. He’s a former assistant clinical professor at University of Maryland in the department of Restorative Dentistry and Endodontics. He’s also a former AAID Implant maxi-course assistant programme director at Howard University College of Dentistry. He has lectured internationally on the topics of restorative dentistry, endodontics and implant surgery. Also, prosthetics, removable and fixed prosthetics, periodontics. Gregori has over 680 published articles globally, several ebooks and textbook chapters. He has earned Fellowship in the AGD, American College of Dentists (ACD), International Congress of Oral Implantology (ICOI). Additionally, Pierre Fauchard, ADI, Mastership in the AGD and ICOI and Diplomat status in the ICOI, American Dental Implant Association (ADIA), International Dental Implant Association (IDIA). A consultant and evaluator for multiple dental companies. He can be reached at [email protected].
Dr Niloufar Rezakhani DMD
Dr Niloufar Rezakhani got her degree from Nova Southeastern University. She is an experienced general dentist with a demonstrated history of working in the hospital and healthcare industry. Dr Rezakhani is a healthcare services professional. She is skilled in endodontics, teeth whitening, veneers. Also, cosmetic dentistry, crowns, implants and full-mouth reconstruction. She can be reached via email at [email protected].
This article first appeared in Laboratory magazine. You can read the latest issue here.
