Date of Award
Master of Science (MS)
Purpose: The specific aims of this retrospective study were 1) to compare the emergence angle of a single implant crown (SIC) of the mandibular first molar to the emergence angle of the natural contralateral tooth, 2) to evaluate the effect of the emergence angle of SIC on the health of the peri-implant soft tissue and 3) to quantify an acceptable emergence angle among SIC. Materials and methods: Ten Marquette University School of Dentistry (MUSoD) patients were included in the study. Each patient was examined clinically and plaque index (PI), probing depth (PD), and bleeding on probing (BOP) measurements were gathered from their mandibular first molar implant crown and contralateral natural unrestored mandibular first molar tooth. An intra-oral scan of the mandibular arch using Lava True Definition scanner was performed. The emergence angles of mandibular first molars obtained by the scan was compared to the gingival indices (PI, PD, BOP) to investigate effect of emergence angle on the health of peri-implant soft tissue. Results: The mean emergence angle measurements showed lingual angles to be greater than buccal angles, both on natural teeth and implant crowns. It also showed implant crowns mean emergence angles to be greater than natural crowns. Emergence angle had no significant effect on PI or PD however, an emergence angle of ≤ 106 degrees on the mesiobuccal and midbuccal surfaces of implant crowns had a significant effect on increasing BOP. Conclusion: Within the limitations of this study, the following conclusions were made: Buccal surfaces of mandibular first molar SICs and contralateral natural teeth were over-contoured in relation to the lingual surfaces. Mandibular first molar SICs were under-contoured when compared to their contralateral natural teeth. Over-contoured emergence angle of ≤ 106 degrees affected BOP values on the mesiobuccal and midbuccal surfaces of the SICs.