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F i x e d - r e m o v a b l e s o l u t i o n f o r a t r o p h i c m a n d i b l e s Introduction Prosthetic rehabilitation on implants in severe- ly atrophic patients is a challenge. In a Cawood and Howell Class VI case, the mandible presents with a depressed ridge form, inadequate in height and width, evident basilar bone loss, and alveolar nerve exposure.1 A mandibular implant overdenture is a viable treatment option for edentulous mandibles, improving overall patient satisfaction compared with a removable com- plete denture.2 These studies document suc- cessful treatment outcomes and better oral health-related quality of life as compared with wearing of complete dentures.3 The number of implants to be placed and the type of retention have been controversially discussed.4–6 The im- plant survival rate of mandibular overdentures is high regardless of the number of implants.7 Therefore, two single standing implants with ball attachments have sometimes been consid- ered a risk and some investigators suggest using four implants with a splinting bar.6, 8–10 In patients with an alternated skeletal max- illomandibular relationship, a fixed-removable solution may be a viable option for soft- and hard-tissue reconstruction and for the All-on-4 concept for the rehabilitation of patients pre- senting with extremely atrophic mandibles (Cawood and Howell Class VI).1, 11 A fixed- removable solution may be a feasible option to overcome the technical complications of other treatment options.4, 12 Moreover, hygienic main- tenance of the prosthesis can be challenging when extensive prosthetic flanges are needed to provide adequate lip and check support to overcome esthetic problems typical of aging.13 The purpose of this preliminary case series study was to report one-year preliminary data on Cawood and Howell Class VI patients reha- bilitated with a fixed-removable solution. This study followed the Strengthening the Reporting of Observational Studies in Epidemiology report- ing guidelines.14 Materials and methods This preliminary investigation was designed as a prospective study conducted according to the principles embodied in the Helsinki Declaration of 1975, as revised in 2008. Completely eden- tulous patients, aged 18 years or older, present- ing with severely atrophic mandibles (Class VI according to Cawood and Howell)1 were enrolled and treated in consecutive order after being in- formed about the nature of the study and pro- viding their written informed consent. All of the surgical and prosthetic procedures were per- formed in a private center in Rome, Italy, by a certified implantologist (MT) between Septem- ber 2015 and February 2016. Exclusion criteria were general contraindications to oral surgery, pregnancy or nursing, intravenous bisphospho- nate therapy, alcohol or drug abuse, heavy smoking (≥ 10 cigarettes/day), radiation therapy to the head or neck region within the last five years, parafunctional activity, untreated peri- odontitis, full-mouth bleeding on probing, and a full-mouth plaque index of ≤ 25%, and allergy or adverse reactions to the restorative materials. Preoperative photographs, radiographs (Figs. 1a–c) and model casts were produced for initial screening and case evaluation. A radio- graphic guide was made by duplicating the relined pre-existent removable complete mandibular denture, if judged viable from an esthetic and functional perspective; otherwise, a new radio- graphic guide was made according to the func- tional and esthetic requirements. A cone beam computed tomography (CBCT) scan (CRANEX 3Dx, SOREDEX, Tuusula, Finland) was taken of each enrolled patient wearing the radiographic guide and a bite index in centric occlusion with an extraoral volume transfer element (Evobite, 3DIEMME, Cantù, Italy), fixed using a dedicated silicone material (3DIEMME). Then, the radio- graphic guide and the bite index were repositioned in the master cast and optical scanning was per- formed. Radiographic and prosthetic data were imported into a dedicated diagnostic and medical imaging software (3Diag nosys 4.2, 3DIEMME). The digitalized model and radiographic guide were accurately superimposed over the recon- structed bone volume by CBCT, based on the volumetric elements, present in both the CBCT volume and the optical scan (Evobite). Four im- plants per patient were planned in the anterior area of the mandible, according to the prosthetic setup. After careful functional and esthetic eval- uation and final verification, the prosthetic- driven plan was approved, and a stereolithographic sur- gical template was fabricated with a newer rapid prototyping technology (New Ancorvis, Bargellino, Italy). One hour before implant placement, patients received a single dose of an antibiotic (2 g of amoxicillin or 600 mg of clindamycin if allergic to penicillin) and professional hygiene therapy. Prior to the start of surgery, the patients rinsed Journal of Oral Science & Rehabilitation Volume 3 | Issue 2/2017 33