Ever since the introduction of dental implants in the 1960s, they have been used worldwide with high success rates and accepted predictability [13]. Initial efforts of implant treatment mainly focused on osseointegration and function, whereas today, esthetics is also regarded as an essential component, which is commonly addressed together with functional goals of rehabilitation with dental implants [15]. In the anterior maxilla, the definition of success embodies several factors in addition to absence of pain, bleeding, or other morbidities [3].
Pink and white esthetic scores (PES and WES) were developed in an attempt to allow objective evaluation of esthetics in implant dentistry [8, 9]. However, esthetic outcomes should measure both an objective assessment by the clinician and a subjective evaluation by the patient [13]. Only a limited number of studies have previously reported on the correlation between the objective evaluation of implants placed in the esthetic zone with patient-reported outcomes [2, 10, 13, 15,16,17].
The results of this study revealed acceptable outcomes in both PES and WES analyses. The mean PES in this study was 10.7, a score that is similar to the one previously reported by Cosyn et al. and higher than those from several other studies [2, 10, 16, 18]. The WES results on the other hand revealed an almost perfect outcome with a mean of 8.6, which was similar to studies by Angkaew et al. and Beekmans et al. and higher than the ones reported by Cho et al. and Gjelvold et al. [2, 10, 15, 16]. Even though variable overall PES and WES were reported on different studies, on a clinical basis, these indices not only reveal a patient-specific objective evaluation for the esthetic outcome but may aid in record-keeping and over-time assessment of anterior implant treatment. Angkaew et al. who also used VAS to determine patients’ perception of the outcomes reported higher VAS scores than our findings, although they found acceptable but lower PES and WES values. It is noteworthy that, as in the present study, they found no significant relationship between PES/WES and VAS scores [2]. On the contrary, similar results in VAS scores were achieved by Cho et al. who reported poor PES and almost acceptable WES results with a statistically significant correlation of VAS [10]. The outcomes of this study did not reveal a significant correlation between PES/WES results and patient satisfaction, which may be attributed to subjective nature of esthetics and the incompatibility of patient perspective with what is considered as an “objectively perfect clinical result”. Therefore, when our findings are considered together with the previous literature, it can be concluded that the outcomes from objective evaluations may not always fall in line with the patients’ satisfaction levels. An implant with perfect pink and white esthetic scores may in fact prove to be unsatisfactory for the patient, which emphasizes the significance of subjective evaluation by the patient when assessing esthetic outcomes.
In the present study, only two implants in patients with thin gingival biotypes failed to reach the clinically acceptable PES level. All other patients with both thick and thin biotypes achieved either acceptable or almost perfect scores for both PES and WES. According to the results of Angkaew et al., the PES/WES scores of patients with thick gingival biotype were significantly higher than those with thin gingival biotype; although no such correlation was detected in this study [2]. Peri-implant soft tissue stability is reported to be associated with gingival biotype, which is a significant parameter for the esthetic outcome of the implant restoration in the anterior region [19,20,21]. However, the results from the present study demonstrate that the gingival biotype may not necessarily play a very central role on esthetics in single implant restorations. Therefore, the authors of this study believe that patients with thin gingival biotypes may also expect to have acceptable esthetic results for single implants in the anterior maxilla so long as proper surgical and prosthetic protocols are meticulously designed and implemented.
The smile line is an indispensable element of esthetic dentistry and an important consideration of any oral rehabilitation. A recent study by Antoniazzi et al. among Brazilian population reported that patients with high smile lines were significantly less satisfied with their smile compared to those with lower smile lines [22]. Even though their study consisted of patients with natural teeth, the analyses from this study similarly found a significant negative correlation between VAS and the smile line of patients with anterior implant restorations. Accordingly, the patients with low and medium smile lines had similar levels of concerns regarding the esthetic aspects of their implants. However, the patients with high smiles lines and significantly lower VAS scores had worse perceptions than both groups. Therefore, patients with lower smile lines more frequently reported favorable esthetic outcomes. Patients with high smile lines are considered a challenge in attaining esthetic results, since the restoration and the gingival tissues are displayed more than those with lower smile lines, where these elements are hidden behind the upper lip [23, 24]. Thus, smile line evaluation should not be skipped during implant consultations in order to accurately meet patient expectations.
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.