Dr. Willie Jack describes and critiques a commonly used implant treatment solution



This article describes a patient referred to the author due to advanced periodontal disease and the subsequent treatment decisions made. The case study shows that when teeth are missing, there are different options available, and the treatment path that was selected. Missing teeth were replaced using an implant bridge on the left and an adhesive bridge on the right, and an explanation of the decisions made and the sequencing of the treatment is offered.

Presentation
The patient was referred to the practice by a nearby general practitioner who had tried to control the patient’s periodontal disease for many years. Bone loss had increased around many teeth, attachment loss had accelerated, and when a few teeth became impossible to manage, the patient was referred for a periodontal and implant consultation.

Treatment plan discussion
The patient was advised that four teeth could not be saved and that, following the extraction of the LR7, LR5 and LL4, the patient needed to be referred to a dental hygienist for intensive hygiene-phase therapy.
Initially, this would involve two long sessions of root-surface debridement under local anesthetic. The full-mouth disinfection approach aims to reduce plaque levels and bacterial load rapidly. The LL6 would also have to be extracted, but that could wait until later.

Three months after the hygiene-phase therapy, its success would be evaluated. The patient’s choices in terms of restorative treatment depended on its success. The likely options included:

1.    A partial chrome denture to restore the missing mandibular teeth at LR5, LL4, LL5, and LL6

2.    On the left side—two implants can retain a three-tooth bridge. Due to the loss of alveolar bone height and the presence of the inferior dental (ID) nerve, the implants would have to be short and placed at LL5 and LL6 where there was slightly more bone above the ID nerve

3.    On the right side—bridgework was discounted on the left in favor of implant therapy, but on the right side, there was insufficient bone above the mental foramen for an implant to be placed. Therefore, an adhesive bridge was recommended, cantilevering from the LR6 into the LR5 space.
The patient advised us that she also wished to have whiter teeth and to have the over-erupted maxillary anterior teeth reduced in length. In addition, she told us that she hated the “black triangles” that had arisen as a result of reduced attachment levels

Treatment recommendation
•    Extraction of LR7, LR5, and LL4
•    Referral to a dental hygienist for full-mouth disinfection
•    Extraction of LL6 and simultaneous placement of two dental implants at LL5 and LL6
•    Whitening of all teeth using bleaching trays at home
•    Restoration of LR5 with an adhesive bridge retained at LR6
•    Restoration of LL4, LL5, and LL6 with a three-unit bridge retained on custom abutments from the implants at LL5 and LL6
•    Esthetic improvement of over-erupted teeth and black triangles by reducing the length of some anterior teeth and providing gingival epitheses.

Short, wide implants
It was long believed that short implants (< 10 mm) were associated with a higher failure rate (van Steenberghe D et al, 1990). In particular, posterior situations are more likely to experience higher loads—the usual method of countering this is with longer implants, but in the mandible, due to the presence of the ID nerve, a limited amount of bone is available. In recent years, wider implants have been seen, not just as a rescue fixture (Langer B et al, 1993), but also as an alternative where longer implants are not feasible.

In edentulous jaws, the use of short implants to restore atrophic mandibles was seen to be an extremely successful and predictable treatment (Friberg B et al, 2007). However, some studies using machined-surface implants were confusing, because it was stated that the posterior mandible was not an important variable, although short implants were considered to be so. The implants in this study were placed between 1982 and 1998 (Naert I et al, 2002).

In addition, the use of a roughened surface has been shown to increase dramatically the surface area available for integration; many variations of this altered surface have been used (Deporter D et al, 2001). Some authors have even found that the altered surface may make up for the short length; 5-year survival rates were only different for short and standard implants where the implant had a machined surface (Feldman S et al, 2006). Success rates of up to 100% have also been found, but here, the implants used were hydroxyapatite-coated, and the mean follow up was only 34 months (Griffin T, Cheung W, 2004).
It was seen that treatment of partial edentulism using implant-supported prostheses could be successful (558 fixtures in 154 patients, van Steenberghe D et al, 1990) with machined-surface, regular-diameter implants. This large, prospective study concluded that smaller fixture size was associated with implant failure. In a study where prostheses were removed after 3 to 4 years in function, the long-term success of these shorter, wider implants in supporting bridgework in the posterior mandible has been shown (Farzad P et al, 2006).

Mandibular implants can be very stable compared to maxillary implants and, in particular, good implant stability can be achieved by using short implants in the posterior mandible (Balleri P et al, 2006).

One-stage, non-submerged implant procedure
Euroteknika’s Natea straight bone-level implants were used in a single-stage surgical procedure using healing abutments. These Astra-compatible implants can be used with healing abutments to avoid a two-stage procedure when placed in the absence of a temporary prosthesis. By utilizing the built-in platform switching, we take the micro-gap away from the bone crest, which gives a more stable long-term bone level. When this is used with short implants, a better crown-to-implant-length ratio results.
The prosthetic margin of the abutment is just below the level of the mucosa, allowing cemented restorations to be more predictable, due to the ease of removing excess adhesive (Buser D et al, 1999). Bone-level implants placed by either one-stage or two-stage protocols showed no sign of long-term bone-level change (Cecchinato D et al, 2007). In another study using tissue-level implants, shorter implants did not fail more than longer implants, leading the authors to state that the use of short implants in the posterior mandible “should make implant therapy simpler and more accessible” (Nedir R et al, 2003).



Alternatives
Some authors have made a case for the use of alveolar distraction in the posterior mandible—even suggesting that it be considered when the crown height is greater than the available bone for implantation (Garcia-Garcia A et al, 2003). There is, however, a high risk of complications (i.e., paraesthesia) when making the cuts necessary so close to the ID and mental nerves. In addition, outcomes should always be compared with the problems associated with bone grafting and sinus augmentation, not to mention nerve transposition.

It is important to explain that the use of short implants in the posterior mandible must be considered alongside “surgical preparation related to bone density (variable protocol), textured (roughened) surface implants are used, operators’ surgical skills are developed and indications for implant treatment are duly considered.” When these are brought together, the survival of short, wide implants is comparable with longer, regular implants (Renouard F, Nisan D, 2006).

Placement of the dental implants
After the hygiene-phase therapy, there was a dramatic improvement in the patient’s periodontal health.
For the implant surgery on the left posterior mandible, I made an initial incision straight across the midline of the crest of the ridge from the distal of the LL3 to the mesial of the LL7 with no relieving incisions, but with gingival sulcular incisions as mesial as the LL1. A full-thickness flap was elevated, and the mental foramen was identified so that it could be avoided.
I extracted the LL6, and the implant sites were marked with a sharp-point bur that easily and accurately penetrated the cortical bone.



Then, a 2.2-mm twist drill was used to drill trial osteotomy sites at the LL5 to 8 mm and at the LL6 to 6 mm. Markers were placed and radiographs were taken to check for alignment and depth, most especially in relation to the ID and mental nerves. Once these had been checked, further preparation was carried out to 8 mm depth with 2.8-mm, 3.5-mm, and 4.2-mm twist drills. The screw tap was used with the hand torque wrench to create a thread in the relatively dense and avascular bone. The fixtures placed were 8.0 mm long and 4.8 mm in diameter, while the fixture mounts were put to one side because Euroteknika’s implants all include these, which also act as impression copings.

Osstell resonance frequency analysis (RFA) readings were taken, and healing abutments (which are enclosed with the implants) were placed on both fixtures. In 8 weeks, the patient’s soft tissues had healed well—the implants were firm and had a good ringing tone on percussion. The healing caps were removed, readings were taken with the Osstell RFA device, and 3M™ ESPE™ Impregum impressions were taken in a closed tray over the impression copings. Two weeks later, the abutments were tightened to 35 Ncm with the hand-torque wrench, and the screw access was sealed. The bridgework was fitted and checked to ensure a clean and passive fit; the color was vibrant and natural, and the occlusion was optimal. Once the checks were complete, a small smear of temporary adhesive was placed inside the bridge retainers, and the bridge was fully seated.



Bio
Willie Jack is currently clinical director of d2dIMPLANTS™ Ltd, the UK distributor of Euroteknika implant systems. Qualifying in 1983 from Edinburgh, he has been involved with implant dentistry since 1992, and has now placed and restored more than 3,000 dental implants. Formerly director of implant dentistry at Oasis Dental Care, he gained his MMedSci masters degree in implantology from Sheffield University in 2009. He is a member of the British Society of Periodontology, the Association of Dental Implantology, and the European Association of Osseointegration. Dr. Jack can be reached at This e-mail address is being protected from spambots. You need JavaScript enabled to view it or via www.d2dimplants.co.uk.

References

Balleri P, Cozzolino A, Ghelli L, et al (2002) Stability measurements of osseointegrated implants using Osstell in partially edentulous jaws after 1 year of loading: a pilot study. Clin Oral Implants Res 4(3):128-132

Buser D, Mericske-Stern R, Dula K, et al (1999) Clinical experience with one-stage, non-submerged dental implants. Advances in Dental Research 13(1):153-161.

Cecchinato D, Bengazi F, Blasi G, et al (2008) Bone level alterations at implants placed in the posterior segments of the dentition: outcome of submerged/non-submerged healing. A 5-year multicenter, randomized, controlled clinical trial. Clin Oral Implants Res 19(4):429-431.

Deporter D, Pilliar RM, Todescan R, et al (2001) Managing the posterior mandible of partially edentulous patients with short, porous-surfaced dental implants: early data from a clinical trial. Int J Oral Maxillofac Implan 16(5):653-658.

Farzad P, Andersson L, Gunnarsson S, et al (2004) Implant stability, tissue conditions and patient self-evaluation after treatment with osseointegrated implants in the posterior mandible. Clin Oral Implants Res 6(1):24-32.

Feldman S, Boitel N, Weng D, et al (2004) Five-year survival distributions of short-length (10mm or less) machine-surfaced and osseotite implants. Clin Oral Implants Res 6(1):16-23.

Friberg B, Gröndahl K, Lekholm U, et al (2000) Long-term follow-up of severely atrophic edentulous mandibles reconstructed with short Branemark implants. Clin Oral Implants Res 2(4):184-189.

Garcia-Garcia A, Somoza-Martin M, Gandara-Vila P, et al (2003) Alveolar distraction before insertion of dental implants in the posterior mandible. British J Oral Maxillofac Surg 41(6):376-379.

Griffin TJ, Cheung WS (2004) The use of short, wide implants in posterior areas with reduced bone height: a retrospective investigation. J Prosthet Dent 92(2):139-144.

Langer B, Langer L, Hermann I, et al (1993) The wide fixture: a solution for special bone situations and a rescue for the compromised implant. Part 1. Int J Oral Maxillofac Implants 8(4):400-408.

Naert I, Koutsikakis G, Duyck, et al (2002) Biologic outcome of implant-supported restorations in the treatment of partial edentulism. Part 1: a longitudinal clinical evaluation. Clin Oral Implants Res 13(4):381-389.

Nedir R, Bischof M, Briaux JM, et al (2004) A 7-year life table analysis from a prospective study on ITI implants with special emphasis on the use of short implants. Results from a private practice. Clin Oral Implants Res 15(2):150-157.

Renouard F, Nisan D (2006) Impact of implant length and diameter on survival rates. Clin Oral Implants Res 17(S2):35-51.

van Steenberghe D, Lekholm U, Bolender C, et al (1990) Applicability of osseointegrated oral implants in the rehabilitation of partial edentulism: a prospective multicenter study on 558 fixtures. Int J Oral Maxillofac Implants 5(3):272-281.