Zygomatic Implants Placed in Immediate Function through Extra-Maxillary Surgical Technique and 45 to 60 Degrees Angulated Abutments for Full-Arch Rehabilitation of Extremely Atrophic Maxillae: Short-Term Outcome of a Retrospective Cohort.

Armando Lopes,Carlos Moura Guedes,Miguel De Araújo Nobre,Mariana Nunes,Ana Ferro,Ricardo Almeida

doi:10.3390/jcm10163600

Abstract

The use of new devices for the rehabilitation of the severely atrophic maxillae needs validation. We aimed to report the short-term outcome of severely atrophic jaws rehabilitated with zygomatic implants with no implant head angulation placed extramaxillary in conjunction with standard implants. Forty-four patients were consecutively included with 77 zygomatic implants (31 abutments of 45 degrees and 46 abutments of 60 degrees) and 115 standard implants. Outcome measures were prosthetic survival, implant/abutment success, complications, modified plaque index (mPLI), modified bleeding index (mBI), mucosal seal efficacy evaluation (MSEE) >4 mm, and Zygomatic implants classification level (ZICL). Two patients (4.5%) were lost to follow-up. No prosthesis was lost; one patient lost one zygomatic implant; two angulated abutments of 60 degrees needed to be replaced in one patient due to an aesthetic complaint; rendering a cumulative success rate at 2-years of 95.3% and 95.9% using patient and implant/abutment as unit of analysis, respectively. Mechanical and biological complications occurred in 13 and six patients, respectively; all resolved. The median mPLI and mBI was 1; MSEE > 4 mm occurred in 17% and 21% of patients at 1- and 2-years, respectively; ZICL1 was registered in 80% of patients. The current protocol enabled good short-term outcomes.

Highlights

Seventy-seven extra-maxillary zygomatic implants were inserted with connection of multi-unit angulated abutments of 60- (n = 46) and 45-degrees (n 31) and 6 mm of height; together with the insertion of 115 standard implants (Table 1)
The present study reported the short-term outcome of fixed prosthesis supported by immediate function zygomatic implants inserted extra-maxillary with 45- and 60-degrees angulated abutments in conjunction with standard implants for the rehabilitation of the severely atrophic maxillae, with a high survival and success rates for prostheses, implants, and abutments
The implant survival of 98.7% is comparable to what is reported in the literature for zygomatic implants inserted either through classical or extra-maxillary surgical techniques

Summary

Introduction

Zygomatic implants are one of the alternatives to bone grafting for fixed prosthetic rehabilitation in the absence of enough residual bone, based on the premises of decreasing treatment time, reducing the number of surgeries and anaesthetic procedures, eliminating donor graft site morbidity, and reducing the overall cost of surgical and prosthetic treatment while maintaining excellent patient satisfaction outcomes [1,2].The indications of zygomatic implants range from the treatment of atrophic maxilla [3,4], ectodermal dysplasia [5] to maxillary reconstruction after maxillectomy in cancer patients [6,7] with favorable results considering cumulative survival rates (CSRs) ranging between 95.2% and 98.6% with 2- to 12-years follow-up [1,8,9,10,11]. The extra-maxillary surgical technique aims to overcome these limitations, by placing the zygomatic implant extra-maxillary (external to the maxillary sinus before anchoring in the zygomatic bone, covered only by soft tissue along its lateral maxillary surface) [11] providing the preservation of the Schneiderian membrane and a decreased vestibular-palatine width of the prosthesis due to the more coronal emergence of the zygomatic implant [13]. In the presence of extreme angulations, material alternatives to overcome that limitation are lacking. In this sense, the inclusion of 45- and 60-degrees abutments could benefit the rehabilitations providing the necessary compensation in the degrees of angulation

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