Displacement of a Dental Implant into the Pterygoid Fossa: A Clinical Report

Comparison of the accuracy of dynamic navigation and the free hand approaches in the placement of pterygoid implants in the completely edentulous maxilla: An in vitro study

Background/purpose

Pterygoid implant is a promising solution for patients with a partially or fully edentulous atrophic maxilla. However, whether dynamic navigation system will improve the accuracy of pterygoid implant surgery is still unknown. This study aimed to compare the accuracy of dynamic navigation and free-hand approaches in pterygoid implant placement in completely edentulous maxilla models.

Materials and methods

Twenty three-dimensional (3D)-printed edentulous maxilla models were assigned to two groups: the dynamic navigation system group and the free-hand group. Two pterygoid implants were planned in the bilateral pterygomaxillary area and then placed in each model. The entry, exit and angle deviations of the pterygoid implants were measured after pre- and post-operative cone-beam CT (CBCT) image fusion. Student's t test and Mann-Whitney U test were used. A P value < 0.05 was considered statistically significant.

Results

A total of 40 pterygoid implants were placed in 20 models. The comparison deviation of the dynamic navigation group and the free-hand group showed a mean (±SD) entry deviation of 0.93 ± 0.46 mm vs. 2.28 ± 1.08 mm (P < 0.001), an exit deviation of 1.37 ± 0.52 mm vs. 3.14 ± 1.82 mm (P < 0.001), and an angle deviation of 2.41 ± 1.24° vs. 10.13 ± 4.68° (P < 0.001). There was no significant difference in the accuracy with regard to the side factors between the navigation group and the free-hand group.

Conclusion

The dynamic navigation system has higher accuracy for pterygoid implant placement in a complete edentulous maxilla than the free-hand approach.

Clinical Outcomes of Pterygoid and Maxillary Tuberosity Implants: A Systematic Review

Background: This study aimed to assess the survival of implants placed in the maxillary tuberosity or in the pterygomaxillary region of the maxilla, based on a systematic review of the literature. Methods: An electronic search was undertaken in three databases. The cumulative survival rate (CSR) was calculated. The log-rank (Mantel-Cox) test was used to compare the survival distributions between some groups. Results: Thirty-eight studies were included, reporting 3446 implants (3053 pterygoid, 393 tuberosity) in 2245 patients, followed up for a mean ± SD of 61.0 ± 36.3 months (min-max, 1-144). A total of 208 pterygoid and 12 tuber implants failed, with a clear concentration of failures in the first year of follow-up and a 10-year CSR of 92.5% and 96.9%, respectively. The survival of pterygoid implants was lower than that of implants in the maxillary tuberosity (p = 0.006; log-rank test), and the survival of implants submitted to early/delayed loading was lower than that of immediately loaded implants (p < 0.001; log-rank test). Non-splinted implants presented higher failure rates. Few cases of intra- or postoperative complications were reported. Conclusions: Implants placed in the pterygoid process/maxillary tuberosity present a high 10-year CSR, although with lower survival for pterygoid in comparison to tuber implants. Pterygoid/tuber implants that are splinted with other implants may present higher survival rates than those that are not splinted.

Clinical Outcomes of CAD-CAM Subperiosteal Implants for the Rehabilitation of Atrophic Jaws

Thanks to the use of new digital technologies and innovations in materials, there has been an increasing interest in subperiosteal implants. These implants are considered to be helpful for the rehabilitation of severe jaw atrophies, as they overcome some disadvantages of endosseous implantology. In the present clinical retrospective study, 18 patients were treated and the clinical outcomes of the treatment were recorded after 12 months of follow-up.

Pterygoid and tuberosity implants in the atrophic posterior maxilla: A retrospective cohort study

STATEMENT OF PROBLEM

Rehabilitation of the partially or completely edentulous posterior maxilla using dental implants is a clinical challenge because of the presence of the maxillary sinus, as well as the low quality and quantity of bone in that region. In addition to bone augmentation procedures, posterior maxillary rehabilitation using implants includes their anchoring in bones such as the zygoma, pterygoid, and maxillary tuberosity, as well as in short implants. However, the performance of pterygoid and tuberosity implants in the atrophic posterior maxilla is unclear.

PURPOSE

The purpose of this retrospective cohort study was to evaluate the survival of tuberosity and pterygoid implants in patients with posterior maxillary atrophy.

MATERIAL AND METHODS

A nonprobability convenient sample of patients who had received fixed prostheses on implants placed in the maxillary tuberosity or pterygoid regions was analyzed retrospectively. Demographic variables included sex (male, female) and age. Implant-related variables included surface characteristics, site of placement, implant design, length, diameter, and anteroposterior insertion angle. Prosthetic-related variables included the type of reconstruction for rehabilitation and loading protocols. Implant survival, complications, crestal bone loss, and follow-up intervals were also documented. Collected data were analyzed at both patient and implant levels. The demographics and implant characteristics of patients receiving pterygoid or tuberosity implants were analyzed with a statistical software program (α=.05). Survival analysis was estimated by using the nonparametric Kaplan-Meier curve.

RESULTS

A total of 119 patients had 183 pterygoid or tuberosity implants inserted. Most implants in the pterygoid region (71.5%) were Ø4.1 mm (87.4%) and 15 mm in length (60.1%). The most common prostheses were complete maxillary reconstructions (49.2%) with late loading (74.3%). The average implant anteroposterior insertion angle was 60.8 degrees. The cumulative survival rate was 97.3% (n=178) during the mean follow-up period of 57 months (range 1 to 168 months). Among all implants placed, 2.7% failed (n=5) within 2 months of their placement. The statistically significant differences noted between tuberosity and pterygoid implants were related to design, surface characteristics, and loading. The average crestal bone loss was 1.5 mm.

CONCLUSIONS

The survival of the implants placed in the maxillary tuberosity and pterygoid regions was high in patients with posterior maxillary atrophy.

Analysis of retrieval of dental implants displaced into ectopic locations between 2015–2017 and 2018–2020: scoping review of literature

Purpose: This study aimed to evaluate differences in 10 items of treatment details in patient regarding cases between 2015–2017 (EP) and 2018–2020 (LP) from scoping literature review of displaced dental implant (DDI) retrievals. Materials and methods: PubMed, Google Scholar, and ScienceDirect were searched using key words including “displaced,” “retrieved,” “migrated,” or “accidental" dental implants. Treatment details were analyzed for the differences between EP and LP in 92 cases from 32 articles published in 13 countries. Statistical significance was evaluated using the Mann-Whitney U-test, Fisher’s exact test, and Pearson’s correlation analysis. Results: In the comparison between EP and LP, there was no significant difference in the number of publication countries (11 vs. 10), number of published articles (17 vs. 15), distributions of cases (50 vs. 42), mean age of patients (55.9 ± 1.8 years vs. 55.3 ± 2.5 years), male-female distribution (31/19 vs. 24/18), and distribution of displacement into the maxillary sinus and other regions (46/4 vs. 34/8), and no significant difference in the Pearson’s correlation between publication years and the number of articles. DDI retrievals utilized intraoral and endoscopic surgeries (61.2% and 82.5%), transoral and transnasal approaches (93.8% and 81.8%), and local and general anesthesia (64.7% and 76.3%) during EP and LP, respectively. Moreover, significant differences were observed in all distributions between the two factors (30/19 vs. 7/33 cases, 30/2 vs. 6/27 cases and 2/12 vs. 9/29 cases) in EP and LP, respectively (P < 0.01). Conclusions: These results suggest that most DDI retrievals in otorhinolaryngology since 2018 have been mostly performed using transnasal endoscopic approaches under general anesthesia.

Evaluation of different surgical approaches to remove dental implants from the maxillary sinus

Dental implant surgery on atrophied maxilla has many risks; in some patients, simultaneous sinus lifting with implant placement must be performed to increase the chances of successful implantation; this procedure can cause implant migration. Eleven patients were diagnosed with implant migration into the maxillary sinus in four anatomical areas: the sinus floor above the alveolar bone, near the junction of the sinus and nasal floor, near the floor of the orbit, and the most posterior aspect of the sinus. Surgical removal was performed through four different direct non-endoscopic transoral approaches depending on the location of the displaced implant. Surgical challenges, surgery duration and postoperative complications were reported. The least challenging surgical intervention was noted when removing the displaced implants from the floor of the sinus through the crestal approach. More challenges were experienced during the surgical removal of anteriorly displaced implants near the roof of the orbital floor due to surgical access and the proximity of vital anatomical structures. Bleeding from the pterygoid venous plexus was profound with the posterior lateral approach. The choice of an appropriate surgical approach to retrieve displaced dental implants from the maxillary sinus depends on the location of the implant and the surrounding vital anatomical structures.