Only a limited number of studies compared esthetic outcomes of implants placed using different protocols [3, 25, 26]. A majority of these studies compared the results of immediate implant placement (type 1) with other protocols. Huynh-Ba et al. found no difference in terms of esthetics between type 1 and type 2 implant placement [25]. Similarly, Boardman et al. observed higher PES results following immediate placement, although not reaching statistical significance [3]. Another study, which reported on patient-related outcomes of immediately loaded single implants in the anterior maxilla, also revealed no statistically significant differences between PES and WES of implants that followed immediate (type 1) and late (type 4) placement protocols [26]. Although no patients in this study underwent immediate implant placement, favorable outcomes in terms of PES, WES, and VAS scores were achieved with type 2, 3, or 4 placement protocols among which no statistically significant difference was found. As for the loading protocols, all implants in this study underwent conventional loading due to a high level of patient compliance, lesser tendency for implant loss, and improved implant survival compared to immediate loading [27]. However, it should be noted that the literature suggests no statistically significant differences between PES and WES outcomes for immediate and delayed loading protocols [28].

The limitations to generalization of the findings of this study include limited sample and errors inherent to retrospective nature of the study. Further studies with larger sample sizes may aid in identifying the efficacy of objective assessment methods in evaluating esthetic outcomes in the anterior maxilla and how they relate to patient-related outcomes. Also, longer follow-ups are required to thoroughly assess the accuracy of PES/WES changes over time to predict any future peri-implant differences. Despite these limitations, the findings of this study provide an additional insight to how the perception of esthetics is affected in the presence of single implants in the anterior maxilla. Moreover, if validated by further research, PES/WES indices may gain ground in routine clinical practice to monitor long-term alterations of single implant restorations and peri-implant soft tissues.