Comparison of stress distribution around all-on-four implants of different angulations and zygoma implants: a 7-model finite element analysis.

BACKGROUND: In recent years, zygomatic implants and the all-on-four treatment concept have been increasingly preferred for rehabilitation of atrophic maxillae. However, debate continues regarding the optimal configuration and angulation of the implants. The aim of this study was to analyze the biomechanical stress in implants and peri-implant bone in an edentulous maxilla with zygomatic implants and the all-on-four concept, using multiple implant configurations. METHODS: A total of 7 models consisting different combinations of 4-tilted dental implants and zygomatic implants were included in the study. In each model, a total of 200 N perpendicular to the posterior teeth and 50 N with 45° to the lateral tooth were applied. A finite element analysis was performed for determination of stress distribution on implants and peri-implant bone for each model. RESULTS: Higher stress values were observed in both cortical and trabecular bone around the 45°-tilted posterior implants in all-on-four models when compared to zygomatic implants. In cortical bone, the highest stress was established in an all-on-four model including 45°-tilted posterior implant with 4,346 megapascal (MPa), while the lowest stress was determined in the model including anterior dental implant combined with zygomatic implants with 0.817 MPa. In trabecular bone, the highest stress was determined in an all-on-four model including 30°-tilted posterior implant with 0.872 MPa while the lowest stress was observed in quad-zygoma model with 0.119 MPa. Regarding von Mises values, the highest stress among anterior implants was observed in an all-on-four model including 17° buccally tilted anterior implant with 38.141 MPa, while the lowest was in the including anterior dental implant combined with zygomatic implants with 20,446 MPa. Among posterior implants, the highest von Mises value was observed in the all-on-four model including 30°-tilted posterior implant with 97.002 MPa and the lowest stress was in quad zygoma model with 35.802 MPa. CONCLUSIONS: Within the limits of the present study, the use of zygoma implants may provide benefit in decreasing biomechanical stress around both dental and zygoma implants. Regarding the all-on-four concept, a 17° buccal angulation of anterior implants may not cause a significant stress increase while tilting the posterior implant from 30° to 45° may cause an increase in the stress around these implants.

Esthetic evaluation of implant-supported single crowns: a comparison of objective and patient-reported outcomes.

BACKGROUND: This study investigated objective and patient-reported esthetic outcomes and their correlation for single-tooth implant restorations in the maxillary anterior region. METHODS: Nineteen patients were included. Gingival biotypes and smile lines were evaluated. Esthetic evaluation was performed according to the pink and white esthetic scores (PES and WES). Patients rated their satisfaction regarding the implant treatment using a subjective outcome questionnaire and a 10-cm visual analogue scale (VAS). RESULTS: The mean PES and WES were 10.7 (range 5-13, SD ± 2.24) and 8.6 (range 8-10, SD ± 0.60), respectively. The overall mean VAS was 8.54 ± 0.36 (range 3.8-9.8). No significant correlation was found between VAS and PES or WES (p = 0.475, p = 0.984, respectively). PES and WES scores for gingival biotypes failed to show any statistically significant difference (p = 0.701, p = 0.831). There was a significant negative correlation between the smile line and VAS; indicating that patients with lower smile lines expressed higher patient satisfaction (p = .001). CONCLUSIONS: Professionally reported esthetic outcomes (PES and WES results) may not correlate with patient-reported outcomes. Smile line is a significant factor in patient satisfaction, which should be evaluated thoroughly prior to implant placement in the anterior maxilla.

Comparing the precision of panoramic radiography and cone-beam computed tomography in avoiding anatomical structures critical to dental implant surgery: A retrospective study.

PURPOSE: The aim of this study was to evaluate the correlations between measurements made using panoramic radiography and cone-beam computed tomography (CBCT) based on certain anatomical landmarks of the jaws, with the goal of preventing complications due to inaccurate measurements in the pre-surgical planning phase of dental implant placement. MATERIALS AND METHODS: A total of 56 individuals who underwent panoramic radiography and a CBCT evaluation before dental implant surgery were enrolled in the study. Measurements were performed to identify the shortest vertical distance between the alveolar crest and neighboring anatomical structures, including the maxillary sinus, nasal floor, mandibular canal, and foramen mentale. The differences between the measurements on panoramic radiography and CBCT images were statistically analyzed. RESULTS: Statistically significant differences were observed between the measurements on panoramic radiography and CBCT for all anatomical structures (P<.05). The correlation coefficients (r) between the paired samples obtained from panoramic radiography and CBCT were closely correlated (P<.05), with r values varying from 0.921 and 0.979 for different anatomical regions. CONCLUSION: The results of this study support the idea that panoramic radiography might provide sufficient information on bone height for preoperative implant planning in routine cases or when CBCT is unavailable. However, an additional CBCT evaluation might be helpful in cases where a safety margin cannot be respected due to insufficient bone height.