Case Report 2

A 45-year old female patient presented for implant placement in the #30 region. Medical history was not significant and the placement of the implant proceeded uneventfully (Figure 9). Following implant placement and healing the patient had the restoration completed to her satisfaction. However, shortly after this the patient complained of an itching on the side of her implant and possible pain that extended to her ear. She also complained of a metallic taste in her mouth. The patient was concerned that she may be allergic to the implant.

To address the patient’s concerns, the implant abutment and crown were removed and a healing abutment was placed. This was done to eliminate the possibility of an allergy to the abutment or the crown. However, the patient continued to complain of similar symptoms. She underwent allergy testing. The results did not indicate that she had a positive allergy. However, after dealing with this for over a year and after several discussions, the patient indicated that she would like to have the implant removed (Figure 10). The site was anesthetized via an inferior alveolar nerve block. A trephine bur was used and a slot was created around the implant (Figure 11). An elevator was then used to loosen up the implant and the implant was removed (Figures 12, 13, 14).

Patient has subsequently healed well and her symptoms appear to have resolved. Currently the site has not been restored with any additional treatment option.

Implant Surface Characteristics and Possible Implications for Allergy

Titanium is the material of choice for intra-osseous use in the medical field due to its high corrosion resistance and biocompatibility [19]. Exposure to titanium is significant, as its corrosion resistance properties have made it an attractive choice for use in many industries. It has been reported that the titanium content in our body is about 50 ppm [20]. It is well understood that metal corrodes while in contact with biologic systems, and as a result releases ions that can activate the immune system by forming complexes with proteins. These complexes are capable of eliciting a hypersensitivity response. In general, the prevalence of metal sensitivity is around 15 %, with nickel sensitivity having the highest prevalence. Hypersensitivity to titanium in dental implants is most likely underrepresented in the literature. Some possible clinical indicators of an allergy include: allergy symptoms after implant placement, short term hyperplastic soft tissue, unexplained implant failures, and a patient having a history of several allergies.

Most dental implants are made from commercially pure titanium (CP titanium) or Ti-6Al-4V alloy.  CP titanium is high-purity titanium with a purity level in the range of 98.9-99.6%.  The metal usually contains trace amounts of other elements such as oxygen, nitrogen, hydrogen, carbon, and iron. CP titanium is further classified into four grades according to the oxygen level in the metal, from 0.18% in CP Grade I to 0.040% in CP Grade IV.  Ti-6Al-4V alloy is a metal that contains 6 wt% of aluminum is and 4 wt% of vanadium. Typical Ti-6Al-4V alloy has an oxygen and hydrogen content of 0.20 wt% and 0.015 wt%, respectively.  An extra-low interstitial (ELI) Ti-6Al-4V alloy with an oxygen and hydrogen content of 0.13% and 0.012% is used as implant biomaterial. As previously mentioned, hypersensitivity to metals is usually associated with the ions formed from the reaction between the implant metal and the surrounding environment. These ions can form complexes with proteins and function as an allergen to cause an allergic reaction.  The ions formed from elements in implant alloys have been found to cause allergic reactions, including vanadium and aluminum. However, the exact mechanisms of titanium allergy are still unclear.

The surface treatments employed in commercial dental implants are usually sophisticated, combining several surface treatment methods with proprietary steps that may not be indicated in the literature.  The surface treatments on several commercial dental implants are summarized below.

TiUnite (Nobel Biocare Holding AG, Zurich, Switzerland):  For this implant, a duplex oxide layer is created using an electrochemical process.  This results in an outside porous film containing an outer layer with micropores of 0.9-5 m in thickness and an inner barrier film without micropores of 5.7-9.3 m in thickness.   The surface has a Ra value of 1.35 m [21].

OsseoSpeed (Astra Tech AB, MÖlndal, Sweden): The surface of OsseoSpeed is created by this same blasting the titanium implant surface with titanium oxide, then followed by a hydrofluoric acid etching procedure.  The OsseoSpeed surfaces have a Ra value of 0.91 ± 0.14 m, respectively [22].  

SLA and SLActive (Institut Straumann AG, Basel, Switzerland):  In the SLA implants, a 2% ammonium fluoride/2% hydrofluoric acid/10% nitric acid solution is used for pre-treatment at 55°C for 30 seconds.  The surface is then coarse grit-blasting with 259-500 m corundum grit, washed, etched with hydrochloric acid/sulfuric acid in a proprietary process. The SLAactive implant are further rinsed under nitrogen protection and stored in saline.  The surface has a Ra value of 1.2 ± 0.03 m [23] The final rinsing under nitrogen and saline storage significantly changes the surface chemical composition between SLA and SLActive. The surface carbon content in SLActive is statistically significantly lower than the surface carbon content in SLA.

Osseotite and Nanotite (3i Implant Innovations, Palm Beach Gardens, FL, USA):  The surface of these implants are created by a dual acid etching process (Osseotite), followed by a sol-gel deposition method to create a discrete crystalline deposition of stoichiometric hydroxyapatite crystals in the size range of 20-100 nm (Nanotite) [24].

Friadent Plus (Dentsply Frident, Mannheim, Germany):  In this implant, large grit blasting (250-500 m) is used first, followed by acid etching with hydrochloric acid/sulfuric acid/hydrofluoric acid/oxalic acid.  The process creates large micropores of 3-5 m in diameter and 2-3 m in depth, as well as small micropores of 0.5-1 m.  The implant has a Ra value of 2.75 m [25].