The Unique Benefits of Mini Dental Implants
This minimally invasive procedure offers numerous possibilities for edentulous patients.
The dental profession is beginning to face an incredible challenge. Dental practices are treating the largest population explosion in US history-the children of post-World War II, who are now reaching retirement and have unique dental restorative needs.
Dental implants have had a tremendous impact in the dental field and have opened new treatment concepts in restorative dentistry. Statistics show the clear need for implant treatment-69% of adults aged 35 to 44 have lost at least one permanent tooth, while 26% of those 65 and over and 44% of the 75-and-over population are edentulous in both arches.1
The aging population is accelerating the need for implant treatment, and within the coming decades, the number of Americans over 65 will grow to represent more than 20% of the total population.2 Within the implant category, mini dental implants (MDIs) represent a promising treatment that has significant potential for growth. The 3M ESPE MDI mini dental implant system (formerly the IMTEC Sendax MDI System), with implants ranging in diameter from 1.8 mm to 2.9 mm, can be applied successfully to stabilize dentures and in other clinical applications. Mini dental implants were accepted by the FDA in 1997,3 and since then studies have found their survival rates to range from 91.2% to 96.3%.4-6 A recent study that followed more than 2,500 implants found a 5-year survival rate of 94.2%.7
MDI treatment is relatively simple to learn and perform, and the minimally invasive procedure can be quickly completed in a general dentist's office. If there is insufficient bone to anchor a conventional implant, extensive surgical interventions can sometimes be required to attain adequate bone width, resulting in considerable cost for patients. Alternatively, the cost of the MDI procedure is significantly more affordable, making it an attractive option for many.8
Case Presentation
The patient, an 85-year-old woman, presented to the office with osteoporosis, an existing lower denture, and six remaining maxillary teeth (Figure 1). The lower denture had been provided to the patient 4 months prior, and she was very unhappy with her inability to masticate and chronic instability during social activities. The patient had begun losing weight due to her inability to maintain proper nutrition with the denture, causing concerned family members to take notice. Her granddaughter, a dental hygienist, had accompanied her to a consultation with another dentist, who suggested root form implants. The proposed treatment plan for this procedure included bone grafting to supplement the width of the lower jaw, and the patient had been cautioned that success with the bone graft was not guaranteed.
The patient and her granddaughter then sought a second opinion about her candidacy for implants. They had heard about MDIs and wondered if these might be a more suitable option for her. It was explained that MDIs, unlike root form implants, are a minimally invasive, no-scalpel procedure, and could be immediately loaded to give her denture stability on the same day as the procedure. A panoramic radiograph showed the patient's bone was 4.5 mm in width, which allowed sufficient room for 1.8-mm MDIs with a 1-mm buffer on each side (Figure 2). (3M ESPE recommends a 1.5-mm buffer; however, it has been found that 1 mm can be sufficient.) The patient was very happy to learn she was a candidate for the procedure and opted to move forward with treatment.
Instead of the standard "four on the floor" treatment, in which four MDIs are placed in the mandible, it was determined that five implants would be more suitable for the patient's condition, giving her one more implant to balance the load. Additionally, with a fifth MDI, denture stability would not be adversely affected should one of the implants be lost at some point.
Local anesthesia of 2% lidocaine and epinephrine 1:100,000 was delivered via three point infiltration: one point at the crest of the ridge, one point lingual, and one point buccal at the five implant locations marked on the patient's tissue. A pilot drill was used to penetrate the cortical plate at the entry points, and pilot holes were drilled to one third of the threaded length of the 13 mm (left two) and 10 mm (right three) implants. Each of the five implants were then inserted in the pilot openings and rotated clockwise with a finger driver until bony resistance was encountered. A winged thumb wrench was used to thread the implants further into place, followed by a ratchet wrench (where needed) to make the final incremental turns. The implants were inserted until the abutment heads, but no neck or thread portions, were visible above the soft tissue (Figure 3). A resistance torque of greater than 35 Ncm was reached at each MDI location to allow for immediate loading using a 3M adjustable torque wrench that breaks away at the 40 Ncm setting.
After this procedure, the patient's denture was adapted to snap onto the implants (Figure 4). Five openings were drilled into the lower denture to fit each of the implants, and blockout shims were then placed over the MDIs. Metal housings were selected and placed over the implants, and the denture was placed in the mouth to confirm a passive fit over the implants and housings. A layer of adhesive was applied to the tissue born surface of the denture, and SECURE Hard Pick-Up Material (3M ESPE, formerly IMTEC) was applied into the relieved areas of the denture and onto the metal housings. The denture was seated in the patient's mouth and she was instructed to bite down for 7 minutes to allow the material to set. After this time had elapsed, the denture and blockout shims were removed and the denture was trimmed and polished, then seated back on top of the implants.
Postoperative radiographs were taken and the patient was instructed to not remove the denture for 48 hours (Figure 5). She left the office very satisfied with the procedure, and the author continued to see her for regular recall visits. Five years later, when she determined she was ready for an upper denture, she requested the MDI procedure for the maxilla as well. This was accomplished with minimal difficulty in a short period, with complete success (Figure 6).
Discussion
This case is an excellent demonstration of how MDIs can be a much more suitable and comfortable procedure for osteoporotic patients, and also demonstrates their patient acceptance and success. The mandibular implants in the case presented have been in place for 7 years now, and the maxillary for 2 years, and the patient is amazed and thrilled with her restored function. The author often hears "complaints" from patients after this procedure that they've gained 5 pounds, which is treated as good news after seeing so many denture patients lose weight due to the inability to maintain proper nutrition. MDI treatment can be a life-altering process for patients who are "dentally handicapped"-those who have been told they do not have enough bone, have too complicated a medical history, or simply cannot afford root form implants. It is an outstanding adjunct for enhancing a practice and making a significant change in patients' quality of life.
References
1. AARP Fulfillment. A profile of older Americans. Washington, DC: AARP; 1993.
2. Murdock SH, Hoque MN. Current patterns and future trends in the population of the United States: implications for dentistry and the dental profession in the twenty-first century. J Am Coll Dent. 1998;65(4):29-35.
3. Christensen GJ. The increased use of small-diameter implants. J Am Dent Assoc. 2009;140 (6):709-712.
4. Ahn MR, An KN, Cho JH, Sohn DS. Immediate loading with mini dental implants in the fully edentulous mandible. Implant Dent. 2004; 13(4):367-372.
5. Mazor Z, Steigmann M, Leshem R, et al. Mini-implants to reconstruct missing teeth in severe ridge deficiency and small interdental space: a 5-year case series. Implant Dent. 2004;13:336-341.
6. Bulard RA, Vance JB. Multi-clinic evaluation using mini-dental implants for long-term denture stabilization: a preliminary biometric evaluation. Compend Contin Educ Dent. 2005; 26(12):892-897.
7. Shatkin TE, Shatkin S, Oppenheimer BD, Oppenheimer AJ. Mini dental implants for long-term fixed and removable prosthetics: a retrospective analysis of 2514 implants placed over a five-year period. Compend Contin Educ Dent. 2007;28(2):92-99.
8. Christensen GJ. The "mini"-implant has arrived. J Am Dent Assoc. 2006;137(3):387-390.
About the Author
Joe Gillespie, DDS
Private Practice
Mt. Pleasant, South Carolina
