Author: Steven Rasner, DMD Private Practice. Bridgeton, New Jersey
Article published in the journal Inside Dentistry | July 2012, Volume 8, Issue 7
Implants: novel treatment includes use of plasma-rich growth factors to augment hard-tissue regeneration prior to implant placement.
The maxillary canine is the most frequently impacted tooth after the third molars.1 Ting, Quick, and Winters reported a prevalence of 0.9% to 3%, depending on ethnicity. They also reported that it is twice as common in females, and is usually unilateral. The literature has also reported that the incidence of palatal-to-buccal impactions is 12:1.1 The extraction and implant placement method used in this clinical case involved a 43-year-old woman with a palatally impacted maxillary cuspid.
No single cause for palatal displacement has been identified. The predominant belief is referred to as the "long path of eruption."2 It has been theorized that this particular tooth has a long, tortuous eruption path, beginning close to the floor of the orbit. For patients under the age of 10, the diagnosis of an impacted cuspid can be aided by the knowledge of a family history or if the maxillary laterals are malformed or missing; after the age of 10, helpful clues are asymmetry in right and left palpation or lack of any ability to palpate.3 There are three basic treatment approaches to the impacted cuspid.
Although one treatment approach is to provide no treatment, this may lead to complications. Problems associated with leaving the impacted canine include early morbidity of the primary canine, leading to restorative challenges resulting from the remaining space, which is often too small for a permanent canine. Cystic formation around the follicular sac is also a risk for the untreated impacted cuspid; the cyst may expand at the expense of the surrounding bone.2 Although uncommon, resorption of the root of the permanent lateral incisor is yet another potential complication; when it does occur, the onset is rapid and aggressive.2
Specifically, the teeth to be extracted are the deciduous canine, permanent lateral, or permanent first bicuspid. This approach postulates that the vertical wall of the alveolus on the palatal side steers the directed eruption. Hence, removing adjacent teeth can result in a secondary correction of the eruption pattern.2 Extraction of the premolar with placement of the canine into this position does not greatly affect esthetics, as minor cosmetic changes to the canine can be accomplished to blend the esthetics. Yet, when the lateral is extracted and the canine erupts into this position, esthetic challenges may result that require more extensive treatment to blend the tooth with the adjacent teeth and provide a natural smile. The issue of determining which tooth to extract is beyond the scope of this article, and its success depends on several factors that still require study.
An alternative approach, which is described in the clinical case presented, involves significant space opening with orthodontics.2 The opening of space alters the relation of the cuspid crown to the roots of the adjacent teeth with a direct influence on eruption patterns. It is noteworthy that the timing of treatment is significantly correlated with the success of these alternative procedures. This case involves a 43-year-old woman. Most orthodontists would agree that the success of any aforementioned treatment modalities is seriously compromised in adult patients with palatally impacted cuspids. The author embraces a "less is best" approach with all corrective procedures, and he supports any interceptive treatment that would avoid removal of the impacted tooth. In 2011, Ting reported that it is unlikely that extracting a deciduous cuspid in patients over the age of 13 would result in a correct pattern of eruption.1
A 43-year-old woman presented to the office for "cosmetic improvement" (Figures 1, 2). A review of her medical history was unremarkable except for a history of significant "dental fear." A dental examination and full-mouth radiographs and panorex revealed an AAP Type 1 periodontal diagnosis with probing depths ranging from 3 mm to 5 mm, with the exception of all remaining (maxillary and mandibular) molars, which had pockets of 4 mm to 6 mm. The patient was missing both maxillary first molars. The occlusion had a Class I molar relationship with anterior spacing resulting from the missing permanent upper left cuspids and maxillary first molars. The patient had minor restorative needs. An examination of her esthetics revealed anterior spacing, failing buccal – cervical composites, and the lack of the upper right cuspid. In fact, the radiographs showed a palatally impacted upper right cuspid.
Figures 1, 2. A dental examination and full-mouth radiographs and panorex of this 43-year-old woman revealed an AAP Type 1 periodontal diagnosis with probing depths ranging from 3 mm to 5 mm, with the exception of all remaining (maxillary and mandibular) molars, which had pockets of 4 mm to 6 mm. The patient was missing both maxillary first molars. The occlusion had a Class I molar relationship with anterior spacing resulting from the missing permanent upper left cuspids and maxillary first molars.
The recommended and accepted treatment plan involved removal of the impacted cuspid and replacement with an implant. It would begin with periodontal treatment including quadrant scaling and root planing along with minor restorative work on teeth Nos. 2, 4, 5, 12, 13, 15, and 20. The impacted left canine would be extracted and the site grafted with subsequent implant place and restoration of the implant. (Because of financial constraints, no treatment to restore the existing lower space would be provided in Phase I.) To augment hard-tissue regeneration, the plan also included the use of plasma-rich growth factors (PDGF).
For removal of the impacted cuspid, the patient was sedated with the protocol of 0.25 mg triazolam, 50 mg Atarax, and 25 mg Benadryl 90 minutes prior to the appointment. She was monitored with a pulse oximeter. After local anesthesia—1.8 cc lidocaine (x) four carpules—a sulcular full-palatal mucoperiosteal flap was laid from teeth Nos. 7 through 14. Upon flap elevation, a #8 surgical carbide bur on a surgical straight handpiece was used over a subtle bulge approximately 1 cm from the ridge crest (Figure 3). After superficial exposure of the clinical crown and root, the tooth was elevated from the site.Figure 3. Upon flap elevation, a #8 surgical carbide bur on a surgical straight handpiece was used over a subtle bulge approximately 1 cm from the ridge crest. After superficial exposure of the clinical crown and root, the tooth was elevated from the site.
Although the literature contains an abundance of mixed reviews, many report that plasma-rich growth factors (PRGF) can play a significant role in regeneration.4 It is an autologous source of growth factors and biocompatible fibrin biomaterial obtained upon activation with calcium chloride. Platelet-derived growth factors (PDGF) recruit stem and progenitor cells and cause local differentiation and expansion of cells involved in wound healing, angiogenesis, and bone growth.5,6 Specifically, the application of PDGF greatly increases the platelet count. This increases the availability of platelets to create a cascade response. The average platelet count in a person’s blood is between 111,000 and 595,000. Using PDGF, the platelet count increases to 1,1000,000.5,6 It is noteworthy that these platelets are only in the grafted area for 5 days, so they "jump start" the process of bone maturation. Growth factors released from the platelets include PDGF, transforming growth factor-beta (TGF), platelet-derived epidermal growth factor (EGF), platelet-derived angiogenesis factor (PDAF), insulin-like growth factor 1 (IGF-1), and platelet factor 4 (PF4). These factors signal the local mesenchymal and epithelial cells to migrate, divide, and increase collagen and matrix synthesis. The net result is an increase in the rate of bone deposition as well as the quality of bone.
In the case presented, PDGF was added to Grafton® DBM Putty (Osteotech, ) — a demineralized putty allograft — and MinerOss (BioHorizons) — a mineralized allograft of cancellous and cortical chips with osteoconductive ability. The outside of the remaining defect was covered with a membrane derived from the patient’s blood (Figures 4-6). The incision was then closed with 3.0 Vicryl suture (Ethicon, Johnson & Johnson).
Figures 4-6. The outside of the remaining defect was covered with a membrane derived from the patient’s blood.
Five months later, the patient presented for implant placement. The same previously used preoperative enteral sedation protocol was followed. After local anesthesia, a small sulcular incision and a full-thickness flap was made from site Nos. 10 through 14. The osteotomy was completed according to the manufacturer’s protocol, and a 3.8-mm x 15-mm BioHorizons implant was placed and the tissue resutured.
Three months later, teeth Nos. 6 through 11 were prepared for full-coverage crowns with 360° shoulders, and impressions were taken from teeth Nos. 6 through 11 using the polyether impression material Impregum™ Medium Body (3M ESPE). The implant in the position of tooth No. 11 was captured with a closed-tray impression (Figure 7). The laboratory was asked to fabricate single-unit restorations (IPS e.max® Press, Ivoclar Vivadent, www.ivoclarvivadent.com) for teeth Nos. 6 through 11. For implant crown No. 11, a zirconia/titanium abutment with an e.max crown was provided. IPS e.max, a lithium-disilicate, has a flexural strength of 360 MPa to 400 MPa. It is highly translucent and can be seated with conventional cementation. The zirconia abutment used was ceramic with a titanium base. The strength of the zirconia abutments was comparable to those of titanium (281 N versus 305 N).7 These abutments have excellent biocompatibility and are especially useful in patients with a thin gingival biotype where gingival show-through of a metallic abutment can lead to graying of the marginal gingiva.
Figure 7. The implant in the position of tooth No. 11 was captured with a closed-tray impression.
The provisionals were removed, and preparations were cleaned with a slurry of pumice and Tubulicid Blue (Dental Theraputics AB) — an excellent antibacterial cleanser for removing the smear layer without opening the dentinal tubules — in preparation for cementation. The implant was placed after removal of the healing abutment, and torqued to 35 Ncm. All six restorations were then seated and luted with RelyX™ Luting Powder and Liquid Cement (3M ESPE) (Figures 8-12). Excess cement was removed after setting and the occlusion was checked and adjusted.
Figures 8-12. The laboratory fabricated single-unit IPS e.max® Press restorations; the patient was very pleased with the final results.
This article has reviewed a treatment option for the impacted maxillary cuspid. Most clinicians would agree that early diagnosis and intervention with orthodontics would be the least invasive and preferred method of treatment. Unfortunately, many of these clinical dilemmas are not identified at an early enough stage to predictably treat with orthodontics. The clinical "cost" of no treatment carries unacceptable risks. The author has offered one solution using an implant and hard-tissue augmentation protocol that also incorporated the benefit of PDGF, which has resulted in an excellent outcome and a highly satisfied patient.