Calibrated Implant Pin Control by Drs. Levente and Catherine Foley Bodak-Gyovai

Categories: Implant Dentistry;
Calibrated Implant Pin Control 

An alternate approach to 3D imaging that still helps set the pilot drill in the right direction


by Drs. Levente Z. Bodak-Gyovai and Catherine F. Bodak-Gyovai


Implant dentistry has evolved from simple, freehand procedures to complex, computer-guided navigation protocols. Cone-beam computerized tomography (CBCT) can be used to produce three-dimensional computerized images and 3D surgical guides for placement of multiple implants, and while these advanced digital technologies have moved to the forefront of implantology, their mastery can require substantial investment of finances, time and effort to maximize success.

There are occasions when immediate placement of a single implant, such as the loss of a front tooth, is necessary to restore cosmesis or functional dentition. In such cases, practitioners may not have access to a 3D surgical guide. Dentists who seek an easy method to insert an implant to replace a missing tooth may consider a technique that is quick, cost-effective and readily available in the dental office. Calibrated implant pin control also provides the ability to adjust the location, trajectory or depth of the pilot drill, which is essential to avoid complications whether using freehand or computer-guided methods.1,2

Placing a dental implant should not be disruptive to the schedule, because the time requirement for a single implant, abutment and crown is comparable to treating a tooth with root canal therapy and placing a crown. The permanent implant tooth may have room anywhere in the dental arch. Although a fixed bridge is an excellent choice, it involves the often-objected invasion of those neighboring teeth. Dental implants are a reliable technique for a permanent tooth replacement.


Case selection and applications
Because placing a dental implant is a surgical procedure, it requires a detailed patient medical history for comprehensive treatment planning. Certain medical conditions should prompt a request to consult with the patient’s treating physician to avoid complications. For example, the physician, not the dentist, can pause anticoagulant treatment. Other conditions warranting medical consultation include history of bisphosphonate treatments, elevated hemoglobin A1C > 6.5%, head and neck irradiation, uncontrolled hypertension, organic heart murmur or antibiotic allergy.

Case selection is essential for success. Start at a healed site of a lost tooth with adequate bone height and width. A small mucoperiosteal flap, utilizing a papilla-saving curvilinear incision, offers clear visibility for the pilot osteotomy drill. After tooth removal, implant osteotomy may be simpler when the alveolar socket is still patent but infection and inflammation have resolved, soft tissue is pursed or closed, and sufficient alveolar bone height and width remain.

Although CBCT may not be available, routine periapical radiography is. Multiangle digital periapical radiography can clearly display vital anatomical structures that may be within the planned trajectory of the pilot drill osteotomy. Multiangle digital periapical radiography offers a variety of applications to identify:
  • Typical landmarks such as the size of the tuberosity, the presence of sinus septae, and the exact location of the antrum and nasal floor.
  • Adequate space to consider the 2 mm safe space over the mandibular canal roof to the apical end of the implant as placing the implant shoulder 2 mm subcrestal.
  • Critical structures including a safety zone at the mental foramen, the mental nerve loop and the true mandibular incisive canal.
  • Quality or limitation of bone, such as at the tuberosity, poor bone quality, maxillary sinus extension and anatomical limits.
  • Unexpected anatomical variants such as a retromolar branch of the inferior alveolar nerve.3
  • Position and orientation of remaining natural teeth, roots and implants.

Creating and using the CIPC
The calibrated implant pin control (CIPC, Fig. 1) combined with digital periapical radiography will guide the pilot osteotomy drill safely to avoid any important anatomical structures.

 Calibrated Implant Pin Control
Fig. 1

It is possible to construct the CIPC by using two straight handpieces, a latch drill, a heatless stone, a thin separating corundum disc and a caliper. Shape the latch drill to match the silhouette of the pilot osteotomy drill, and form a 1-mm-long, 0.5-mm-wide tip. Create grooves at sites you select, such as at 5 and 11 mm measured from pin tip along the shaft. Cut the latch drill to a length of 17 mm and smooth with a rubber wheel. At the end of the latch drill, create a groove to attach a long dental floss for safety and the CIPC is now complete. I chose a 17 mm total length to prevent interocclusal interference as the patient occludes on the bite plate of the sensor holder.

Using the CIPC to measure osteotomy depth, slip a small-diameter orthodontic elastometric separator ring onto the CIPC and, with a straight hemostat, introduce it into the pilot osteotomy. Adjust the ring to the entrance of the osteotomy orifice for depth length reference. The ring on Fig. 1 illustrates depth at 9 mm. With the CIPC in situ, expose a digital periapical radiograph.

This CIPC procedure is similar to the well-known root canal pin control, where I use a root canal file with a small rubber disc, and slide it into the root canal to determine the root canal length on a periapical radiographic view.


Determining bucco-lingual relation
Comparison of the digital image of the straight periapical radiographic view with the mesial and distal projections is used to determine the bucco-lingual relation of an object of interest, per Clark’s horizontal tube shift rule.4 When the tube is shifted horizontally, the object moves in the same direction on the screen if it is located on the lingual side. For example, when the pilot osteotomy is near the mental foramen, it can be directed as to bypass the foramen on the lingual side.

Richard’s buccal object rule5 describes vertical tube shift. When the object of interest is on the buccal side, it moves in the same direction as the X-ray beam is directed. For example, the inferiorly directed beam shifts the buccally located inferior alveolar canal apically, related to the tip of the CIPC on the screen. Similarly, the coronally aimed beam moves the buccally located object on the view coronally, closer to the CIPC.

The benefit of using the CIPC is that the tip of the pin is at the same location as the pilot drill tip in the osteotomy. Knowing the calibrations of the CIPC, the exact distance measurements are obtained in actual millimeters to a vital structure by using the software length measurement on the screen.


Calculating magnification distortion

Whether using short or long cone, or bisecting or paralleling techniques, there are inherent distortion errors of intraoral periapical radiography. Magnification discrepancies of foreshortening or elongation will be present on the views of the screen. However, because the 1-mm-long tip of the CIPC in the pilot osteotomy will suffer the same magnification error as the distortion of the immediate intraosseous surrounding anatomy, the distance from the end of that 1-mm CIPC tip to the nearby vital anatomy will receive the same magnitude of magnification distortion. This dimensional change will alter the tip of the CIPC to the same degree that it will affect the short distance from that end to the nearby vital structure. This permits calculating the distances to negotiate tight intraosseous spaces for the implant osteotomy and to avoid critically important anatomical landmarks.

Next, insert the implant into the completed osteotomy. Place the healing plug and pack the saved autogenous osteotomy bone graft, then cut a small collagen plug cover. For primary closure, use resorbable sutures to prevent salivary contamination. Conclude the procedure with final periapical radiographs and photographs.

For a permanent implant, I allow time for osseointegration per two-stage protocol. When it’s time to test implant osseointegration, locate the implant by using a pin for a periapical radiograph. To uncover the healing plug under soft and hard tissues, use a highspeed #4 round bur.

Test the osseointegration with the guide pin and prepare room with sulcus reamers to insert the selected implant abutment and proceed with crown preparation. Make the final radiographs and photographs and schedule a six-month recall.


Case 1

This 77-year-old patient requested implant replacement of long-lost #30 and #31 (Fig. 2). With the help of CIPCs in the pilot osteotomies (Figs. 3–5), I inserted at #30 a 4.5-by-8-by-3-mm implant and at #31 a 5-by-6-by-3-mm implant, both from Bicon, into the completed osteotomies (Fig. 6). I located the implant with the use of an explorer (Fig. 7), assessed osseointegration and placed the abutments into the implant wells (Fig. 8). PFM crowns were bonded to complete the treatment (Fig. 9).

Fig. 10 shows the two-year follow-up.
Calibrated Implant Pin Control
Fig. 2
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Fig. 3
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Fig. 4

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Fig. 5
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Fig. 6
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Fig. 7

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Fig. 8
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Fig. 9
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Fig. 10


Case 2

This 77-year-old patient fractured #14 (Fig. 11). After atraumatic sectioning removal of the roots (Fig. 12) and healing of the soft tissues, and with the help of the CIPC (Fig. 13), I could locate just enough space next to the antrum for a 4.5-by-8- by-3 mm implant (Fig. 14). The implant was inserted precisely between the root and antral wall without touching them, and I completed implant tooth #14 (Figs. 15 and 16). Fig. 17 shows the two-year follow-up.

Calibrated Implant Pin Control
Fig. 11
Calibrated Implant Pin Control
Fig. 12
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Fig. 13
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Fig. 14
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Fig. 15
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Fig. 16
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Fig. 17


Conclusion
Periapical radiography is routine before and immediately after implant surgery.6 Also, intraoperative periapical radiography is used for many dental procedures. Employing CIPC periapical radiography imparts negligible additional ionizing radiation. With my 0.04-second exposure time, a patient receives an estimated 0.08-microsievert effective dose. Investigators using the same X-ray tube assessed 0.8-microsievert effective dose at 0.4 second average exposure time,7 indicating excellent ALARA compliance.

Of the 200 short implants I placed in our office, I have never encountered a fractured or loose implant or abutment, despite a variety of challenging placements. My series includes cases requiring a 15-degree abutment. In cases with reduced alveolar bone height, using short implants may avoid bone augmentation. Short and strong, as illustrated (Fig. 18) with a 10-year follow-up (Fig. 19).

Placing dental implant teeth can change lives, and is one of the most rewarding aspects of dental practice.

Calibrated Implant Pin Control
Fig. 18
Calibrated Implant Pin Control
Fig. 19
 

References
1. Tullarico M, Esposito M, Xhanary E, Caneva M, Meloni SM. “Computer Guided Vs. Freehand Placement of Immediately Loaded Dental Implants: 5-Year Post Loading Results of Randomized Controlled Trial.” Eur J Oral Implantol. 2018; 11(2): 203–13.
2. Mandelaris GA, Stefanelli LV, and DeGroot, BS. “Dynamic Navigation for Surgical Implant Placement. Overview of Technology, Key Concepts and a Case Report.” Compendium. 2018; 3(9): 614–21.
3. Filo K, Schneider T, Kruse AL, Gratz Lochner, KW, Lubbers HT. “Frequency and Anatomy of the Retromolar Canal Implications for the Dental Practice.” Swiss Dent J SSO 2015; 125: 278–85.
4. Clark CA. “A Method of Ascertaining the Relative Position of Unerupted Teeth By Means of Film Radiography.” Odontol Soc. R. Soc. Med. Trens. 1909; 3: 87.
5. Richards AG. “Technique for Roentgenographic Examination of Impacted Mandibular Third Molars.” J Oral Surg (Chic).1952; 10(2):138–41.
6. Saltzburg N, Kang P. “Observed Healing of an Immediately Placed Implant in a Molar Site Without Bone Replacement Graft or Primary Closure.” Compendium. 2020; 41(6): 326–30.
7. Granlund C, Thilander-Klang A, Ylhan B, Lofthag-Hansen S, Ekestubbe A. “Absorbed Organ and Effective Doses From Digital Intra-Oral and Panoramic Radiography Applying the ICRP 103 Recommendations for Effective Dose Estimations.” Br J Radiol. 2016; 89(1066): 20151052.


Author Bio
Author Dr. Levente Z. Bodak-Gyovai obtained his dental education at Semmelweis University in Budapest, Hungary, where he became an assistant professor, and from McGill University in Montreal, where he earned a MSc degree. Bodak-Gyovai continued postgraduate training at the University of Pennsylvania, where he became an assistant professor in the dental school and published a textbook on oral medicine. He later earned certification in orthodontics/orthopedics from the United States Dental Institute and in Bicon implantology from the Bicon Institute. After 44 years in general dental practice in Media, Pennsylvania, he recently retired.


Author Dr. Catherine Foley Bodak-Gyovai is a neurologist and pediatrician who is the author or co-author of 70 peerreviewed medical research studies, reports and abstracts. A graduate of the University of Pennsylvania School of Medicine, Bodak-Gyovai taught at the Temple University School of Medicine, the University of Pittsburgh School of Medicine and Jefferson Medical College in Philadelphia. She recently retired from her specialty medical practice at Nemours Children’s Hospital in Wilmington, Delaware. After her marriage to Dr. Levente Bodak-Gyovai, she developed an interest in the medical aspects of oral health and restorative dentistry.



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