Tilted versus axial implant distribution in the posterior edentulous maxilla: A CBCT analysis

Abstract

Objectives: This study aimed to determine whether distally angulating an implant is a successful strategy to avoid the maxillary sinus and the need for bone augmentation, while increasing the anterior-posterior (A-P) implant distribution in the edentulous maxilla. Materials and Methods:In 115 patients with edentulous maxillae, virtual implant planning was performed utilizing cone-beam computer tomographs. Axial (8 mm length) and tilted (12 mm length) dental implants with 30-degree and 45-degree angulation were virtually positioned to avoid entering the maxillary sinus, while maximizing A-P distribution. Measurements were made between the tilted and axial implants to assess the change in A-P distribution of implants at the implant and abutment levels.Results: Forty-seven sites (20.4%) were not able to have either treatment modality with insufficient bone for implant placement. Axial implants were placed more distally than 45-degree and 30-degree tilted implants in 24% and 42% of sites, respectively. The average change in A-P spread measured at the implant level, for 30-and 45-degree tilted implants was −0.25 mm (95% CI −0.76, 0.26) and 1.9 mm (95% CI 1.4, 2.3), respectively. When measured from the center of each multi-unit abutment the average increase in A-P distances for tilted implants appears larger in the 30-degree and 45-degree groups by 0.97 mm and 1.74 mm, respectively compared to measurements at the implant level.Conclusions: Angulating 12 mm implants provides a limited increase in A-P distribution of implants in edentulous rehabilitation in most situations. In certain patients, the use of 8mm axial implants may provide a greater A-P spread.

Application of Implant Healing Abutment Supporting Vertical Bone Augments in the Posterior Mandibular Area

“…32 CBCT can accurately reflect the three-dimensional position of implant placement and can intuitively evaluate the quality of surgery, but beam sclerosis artifacts have a certain impact on the measurement results. 33 When the peri-implant bone thickness is <1 mm, the measurement accuracy of CBCT decreases, and compared with histology, CBCT underestimates the depth of the bone defect by 0.5−1.17 mm. 34 Therefore, it is recommended to combine parallel projection PR and CBCT to achieve the most objective measurement effect.…”

“…It can only reflect the bone level of the implant in the mesial and distal directions and cannot evaluate the bone level of the buccal and lingual side of the implant or when disk resorption occurs . CBCT can accurately reflect the three-dimensional position of implant placement and can intuitively evaluate the quality of surgery, but beam sclerosis artifacts have a certain impact on the measurement results . When the peri-implant bone thickness is <1 mm, the measurement accuracy of CBCT decreases, and compared with histology, CBCT underestimates the depth of the bone defect by 0.5–1.17 mm .…”

Treatment alternatives for the rehabilitation of the posterior edentulous maxilla

“…However, the failure of just one of the four fixtures, particularly either of the tilted ones, usually represents a major setback, as in many instances the whole prosthetic structure cannot be biomechanically supported by the remaining implants in the long term predictably. It is important to keep in mind that excessive cantilever length can lead to deleterious strain on the implants and prosthetic components, which may increase the risk of biological and biomechanical complications 107,108 . With the purpose of addressing the potential limitations of the “All‐on‐4” protocol, other similar treatment approaches based on the use of a higher number of implants (e.g., six or eight) have been proposed, with similar therapeutic success 109–111 .…”

“…It is important to keep in mind that excessive cantilever length can lead to deleterious strain on the implants and prosthetic components, which may increase the risk of biological and biomechanical complications. 107,108 With the purpose of addressing the potential limitations of the "All-on-4" protocol, other similar treatment approaches based on the use of a higher number of implants (e.g., six or eight) have been proposed, with similar therapeutic success. [109][110][111] Some of these advanced protocols involve the placement of long, tilted implants that are anchored in the pterygoid or zygomatic region (Figure 10).…”

Assessment of Maxillary Molars Interradicular Septum Morphological Characteristics as Criteria for Ideal Immediate Implant Placement—The Advantages of Cone Beam Computed Tomography Analysis

“…In addition to morphological examination of anatomical structures, CBCT and related software also have the possibility for the insertion of the virtual implant [16,17]. Using a virtual implant assessment program, Chen and collaborators [18] estimated the interradicular septum bone in the region of the first and second mandibular molars, as a place for implant placement, since the insufficient dimension of the interradicular septum could present a gap between the implant and bone [3,19].…”