Mandibular Anterior Region Implant Placement
Dr. Michael Sonick is a full time practicing periodontist and implant surgeon in Fairfield, Connecticut. He is also an active teacher, clinical researcher and author. He is a diplomate of the American Board of Periodontology and on the Editorial Board of Contemporary Esthetics and Restorative Practice. He currently is a Guest Lecturer at New York University School of Dentistry in their international dental program and was previously a Clinical Assistant Professor in the Department of Surgery at Yale University School of Medicine.
OsseoNews, Inc. (ON): Dr. Sonick the mandibular anterior region presents certain challenges to the selection and placement of implants because of the narrow ridge and limited mesial-distal dimensions. In general, what would be your recommendations?
Dr. Sonick Each region of the mouth presents with certain problems. The mandibular anterior region has some very definite limitations as far as space is concerned in the mesial-distal dimension. If you place adjacent implants less than 2mm apart you increase the chance of complications, including loss of bone and papillae. In the mandibular anterior region where space is at a premium you have to treatment plan for maximum utilization of the implants you have space to place. We like to see a minimum of 3.0 mm of bone between implants and 1.5 mm of bone between implants and natural teeth to preserve bone and proper anatomy.
ON: How would you recommend restoring a patient who is missing the four mandibular incisors?
Dr. Sonick This is a kind of situation we frequently see. In general, the best way to approach this kind of situation is to place two narrow platform implants and to deliver a four-unit fixed partial denture.
ON: What diameter implants would you recommend for this case and where would you place them?
Dr. Sonick My first choice would be to place two 3.25 mm implants with a 3.4 mm platform in the #23 and 26 positions previously occupied by the mandibular lateral incisors. The fixed partial denture would rest on these two abutments and the two central incisors would be replaced with pontics. This is a relatively simple treatment plan with a very high degree of success.
ON: What about replacing a single mandibular anterior tooth with an implant?
Dr. Sonick This is often a very challenging situation. It is very difficult to place a narrow platform implant in the limited space available and to fabricate a crown to fit over the abutment in that space. I would recommend a 3.25mm implant but only if there is adequate space. The average mandibular central incisor has a CEJ of 3.5 mm. If an implant with a 3.4 mm platform is used, we would like for there to be 6.5 mm of space in a mesial-distal dimension in the edentulous space between the teeth. This would allow for 1.5 mm between the implant and adjacent tooth on each side. If less bone is available you might be better off with a conventional fixed partial denture.
ON: How would you approach the replacement of the two mandibular central incisors?
Dr. Sonick Again this is a very challenging situation because of the limitations in space available for implant placement. I would recommend a single narrow platform implant supporting the abutment crown with a splinted cantilevered crown. This would be a two unit bridge with a single cantilever. Another option, although less esthetic, is to place the implant in the center of the embrasure and make one large crown to look like two central incisors. This restoration would be functional but not nearly as esthetic.
ON: What kind of diagnostic materials are necessary for cases like these?
Dr. Sonick At the very least I would say that the restorative dentist should prepare mounted diagnostic casts with full wax-ups of the ideal final restoration or alternative restorations. A clear acrylic surgical stent indicating the ideal positioning of the implants should also be provided, especially if the surgeon is relatively inexperienced.
