Abstract: PURPOSE: The aim of this study was to analyze the feasibility of zygomatic implant quad approach in patients with tooth agenesis. METHODS: Based on the data from cone-beam CT (CBCT), twenty one patients with tooth agenesis who were planned to receive zygomatic implant quad approach were enrolled. The radiographic bone-to-implant contact (rBIC) of each zygomatic implant placed virtually in patients' zygomatic segment was measured. SPSS 25.0 software package was used for statistical analysis. RESULTS: Twenty patients' plans of zygomatic implant quad approach were completed (12 men and 8 women). A total of 80 zygomatic implants were placed virtually and the average rBIC of zygomatic segment was (13.85±3.29) mm. The rBIC values of 40 mesial zygomatic implants and 40 distal zygomatic implants were (13.80±3.74) mm and (13.90±2.81) mm, respectively(P>0.05). The average rBIC in male of 24 mesial zygomatic implants and 24 distal zygomatic implants were(14.21±4.08) mm and(14.31±3.18) mm, respectively, slightly higher than those in female of 16 mesial zygomatic implants and 16 distal zygomatic implants, which were (13.18±3.18) mm and (13.29±2.10) mm, respectively. There was no significant difference between the two groups (P>0.05). The average rBIC of 15 extra sinus zygomatic implants, 46 against sinus lateral wall zygomatic implants and 19 intra-sinus zygomatic implants were (16.27±2.95), (13.87±3.10) and (11.88±2.78) mm, respectively. There was significant difference between the extra sinus zygomatic implants and the other two(P<0.05). CONCLUSIONS: It is feasible to plan zygomatic implant quad approach for patients with tooth agenesis. Zygomatic implants can get adequate rBIC in zygomatic segment and to provide sufficient support and retention of the superstructure.

Key words: Tooth agenesis, Zygomatic implant quad approach, Bone-to-implant contact