Effectiveness of prosthetic rehabilitation and quality of life of older edentulous head and neck cancer survivors following resection of the maxilla: a cross-sectional study

To evaluate the effectiveness of prosthetic rehabilitation, as well as the quality of life (QOL) of older edentulous maxillectomy patients. Effectiveness of the complete denture obturator prosthesis and QOL of N = 44 older edentulous patients who had resection of the maxilla and were restored with a definitive prosthesis that was in use for a minimum of 1 year was assessed using three instruments: European Organization for Research and Treatment of Cancer (EORTC) Quality of Life Core Questionnaire (QLQ-C30), Head and Neck Cancer Module (QLQ-HN35), and Obturator Functioning Scale (OFS). Data analysis was performed by one-way analysis of variance (ANOVA) on ranks, Spearman rank-order correlation, and hierarchical multivariable rank regression at α = .05 level of significance. Participants’ gender (P < .001), adjuvant treatment (P = .016), surgical approach (P = .017), size of the maxillary defect (P = .028), participants’ prosthetic history (P = .047), and dental status of the mandible (P = .038) were significantly related to the self-reported effectiveness of the complete denture obturator prosthesis. Perceived functioning of the prosthesis (P = .001), participants’ gender (P = .002), the American Society of Anesthesiologists (ASA) physical status (P = .027), and surgical approach (P = .039) were significant predictors of QOL. Restoration of the edentulous maxillectomy defect is challenging. An effective definitive complete denture obturator appeared to be the strongest predictor for advanced quality of life in older maxillectomy patients. The physical status of the older participants significantly affected the overall QOL, but did not influence the self-reported functioning of the complete denture obturator prosthesis.


Introduction
More than 50% of the new annually diagnosed worldwide head and neck cancer (HNC) cases occur in patients after the age of 65 [1]. As the world population ages, this digit is anticipated to increase; however, there is less evidence regarding therapeutic strategies and treatment and rehabilitation guidelines for older patients since they are generally underrepresented in clinical trials [2]. Furthermore, their additional chronic diseases could significantly affect not only the available treatment options, but also their survival probabilities and QOL. The incorporation of comorbidity evaluation in the preoperative staging of patients with HNC ≥ 65 years old is of utmost importance [3,4]. Previous studies support the use of the American Society of Anesthesiologists (ASA) physical status classification as an estimate of comorbidity evaluation in older surgical patients with HNC since it retains its prognostic ability beyond the perioperative period; it is an appropriate prognostic factor of postoperative morbidity and is significantly related to the QOL following resection [4][5][6].
HNC and the consequent treatment can be life-changing generating anxiety and distress. When the tumor involves the maxilla, a maxillectomy is required. The maxillectomy is a radical surgical resection involving the removal of a section or the total of the maxilla producing severe defects [7]. HNC survivors with maxillectomy, face numerous functional, and psychosocial post-therapeutic deficits, such as compromised speech and swallowing, defective appearance, disturbed body image, and elevated psychological disruption since the lifepreserving surgical resection leads to critical physical deformities that have a profound effect on QOL [8]. Although vascularized free tissue transfers offer more reconstructive options, microvascular surgery is associated with higher morbidity, postoperative complications, and worse functional outcomes in the elderly population; therefore, prosthetic rehabilitation using obturator prosthesis is still the most common treatment option [9]. Obturators could rehabilitate the patients with maxillectomy to a nearly normal degree of function since they can re-establish oronasal separation; prevent food regurgitation to the nasal and sinus cavities; restore speech, mastication, and swallowing; provide appropriate lip and check support; reduce facial deformity; address esthetic concerns; and restore their QOL. The restoration of the edentulous patient with maxillectomy could be considerably demanding considering the lack of the important retentive elements of the remaining dentition. Several studies are evaluating the perceived functional prosthetic outcome, as well as the overall QOL in patients with resection limited to the maxilla; however, all of them included both younger and older participants and most participants were partially dentate following resection [10][11][12][13]. The authors could not identify any studies evaluating the rehabilitation challenges of older edentulous maxillectomy patients. The aim of this survey was to evaluate the QOL of older edentulous maxillectomy patients in relation to their residual long-term functional, social, esthetic, and psychological disabilities, as well as to assess the self-reported efficacy of the maxillofacial prosthetic outcome in restoring the resultant maxillectomy defect. The null hypothesis was (1) QOL and perceived prosthesis functioning in older edentulous patients with maxillary resection were not affected by demographic and disease-related characteristics nor by the EORTC cancerrelated related functioning symptom measures (C-FSM) and the head and neck cancer-specific symptom measures (HNC-SM) and (2) the perceived functional prosthetic outcome did not affect the QOL of the older edentulous patients with resection of the maxilla.

Materials and methods
The study was performed at the National and Kapodistrian University of Athens (NKUA) Evaggelismos General Hospital. The study protocol was approved by the ethics committee of NKUA (2015-268), in accordance with the Helsinki declaration and the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guidelines. The research protocol included 44 maxillary resection patients with a resultant edentulous maxillectomy defect. The defect was restored by a maxillofacial prosthodontist (IIA) who fabricated the definitive complete denture obturator prostheses from 01-2015 to 12-2016. The inclusion criteria followed were (1) age ≥ 65 years old; (2) history of maxillectomy due to oncologic surgery; (3) Brown Class 2 vertical dimension of the maxillectomy defect; (4) Brown a, b, or c remaining horizontal palatal component; and (5) edentulous participants that were using a definitive complete denture obturator prosthesis for a minimum of 1 year [14]. At the time of the interviews, the maxillofacial prosthodontist evaluated the prostheses that were in good condition and did not require additional adjustments. The exclusion criteria were (1) patients with a history of mental and/or cognitive disorders, (2) surgical resection extending to other structures of the head and neck aside from the maxilla, (3) history of surgical reconstruction of the defect, (4) secondary closure of the defect by granulation tissue, (5) history of implant placement, (6) topical recurrence, and (7) ongoing oncologic therapy. QOL was assessed using the EORTC QLQ-C30 [15,16] and the QLQ-HN35 [17,18] that have both been validated in Greek [19,20]. The perceived functioning and effectiveness of the complete denture obturator prosthesis was evaluated by the OFS [21] that was translated from English to Greek (forward translation) and then from Greek to English (backward translation) by two independent translators.
Due to the non-normal distribution of the obtained data, nonparametric statistical methods were followed. One-way ANOVA on ranks was employed to evaluate the relation between the demographic and disease-related characteristics and QOL, as well as the self-reported functional prosthetic outcome. Spearman's rank correlation was used to investigate the interrelations between the calculated scores of QOL, OFS, C-FSM, and HNC-SM. A hierarchical multivariable rank regression was employed to recognize the most significant covariates of QOL and self-reported effectiveness of the prosthesis, as well as to determine whether the perceived effectiveness of the prosthesis was a strong covariate of QOL. For the statistical analyses, the SPSS software was used (IBM SPSS Statistics for Windows, v26.0; IBM Corp) at a = 0.05 level of significance.

Results
The profile of the 44 participants is presented in Table 1, and the correlations between demographic and diseaserelated characteristics and C-FSM, HNC-SM, as well as QOL, and self-reported functional prosthetic outcome are presented in Table 2. The effect of C-FSM and HNC-SM on QOL and prosthesis functioning is presented in Table 3. QOL was significantly related to physical  Table 4 shows the prosthesis functioning challenges that were significantly associated with improved QOL. More challenges with the complete denture obturator prosthesis led to poor QOL (r = − 0.58, P < 0.001). Modules significantly associated with impaired QOL were avoidance of family/social events (r = − 0.55, P < 0.001), difficulty in talking in public (r = − 0.53, P < 0.001), "funny" appearance of the upper lip (r = − 0.53, P < 0.001), difficulty in being understood (r = − 0.50, P = 0.001), difference in voice (r = − 0.47, P = 0.001), upper lip numbness (r = − 0.46, P = 0.002), trouble in hearing (r = − 0.39, P = 0.001), difficulty in inserting the obturator (r = − 0.37, P = 0.001), and nasal leaking on swallowing food (r = − 0.45, P = 0.002). Regression models are presented in Table 5. Participants' sex (P < 0.001), employment status (P = 0.01), additional treatments (P = 0.016), surgical approach (P = 0.017), size of the horizontal palatal aspect of the maxillectomy defect (P = 0.028), previous prosthetic maxillary experience (P = 0.047), and dental status in the mandible (P = 0.038) were the strongest variables affiliated to ideal functioning of the complete denture obturator functioning. Obturator functioning scale total score (P = 0.001), participants' gender (P = 0.002), ASA status (P = 0.027), and surgical approach (P = 0.039) were the strongest covariates for improved QOL.

Discussion
In the present survey, the null hypotheses were rejected. QOL and perceived effectiveness of the prosthesis in the older edentulous maxillectomy participants were affected by demographic and disease-related characteristics, as well as C-FSM and HNC-SM, whereas the perceived function of the complete denture obturator prosthesis significantly influenced postoperative QOL. A self-reported functional and efficient compete denture obturator prosthesis appeared to be the strongest predictor for advanced QOL in older edentulous participants. This outcome was compatible with earlier reports conducted in the general population [10][11][12][13].
Attributes of complete denture obturator functioning specifically important for enhanced quality of life were the restoration of participants' speech, swallowing, and appearance, parameters that significantly complicated patients' daily life and routine. Many older participants stated that they were often distressed due to their prosthesis-related difficulties that often interfered with their ability to participate in a public conversation and, therefore, complicated their social relationships. In addition, the sustained attempts to insert the obturator correctly caused anxiety to most participants since this constituted a persistent reminder of their affliction. Furthermore, it was interesting that, alike earlier studies in the general population, older women participants appeared to be more affected since they presented with significantly lower physical and cognitive functioning and QOL scores, reported more problems with swallowing, social contact, and insertion of the prosthesis when compared to their men peers [12,22]. Pain and fatigue were also significantly higher in the female participants' group, factors that were also important determinants of poor QOL in the previously mentioned studies [12,22]. Consistent with earlier studies in the general population, the extent of the primary tumor affected speech intelligibility, eating capability, and overall perceived effectiveness of the complete denture obturator prosthesis in older participants [10,11]. Generally, the principal factors associated with effective prosthetic rehabilitation are adequate stability, support, and retention of the obturator prosthesis, parameters particularly important in edentulous patients, since retention of complete denture obturator prosthesis greatly depends on the size and the location of the tumor, the size and the extent of the resultant defect, the remaining portion of the premaxilla, and the available tissue undercuts [23][24][25]. In the present study, the extent of the horizontal palatal component of the palatal defect was significantly related to the self-reported function of the prosthesis. Participants with a resultant Brown a horizontal component reported better overall functioning of the prosthesis, improved speech, and less emotional functioning issues when compared with participants with a more extensive and prosthetically challenging Brown b or c palatal component. Nevertheless, the lack of significant association between the size of the defect and the overall QOL was also consistent with earlier studies since many participants had probably accepted their limitations and were adjusted to their prosthesis over the 1-year period of time between the delivery of the prosthesis and the interview [10,11]. Furthermore, the fact that they survived such a severe life-threatening disease could have outweighed their residual long-term disability, whereas the expertise of the treating maxillofacial prosthodontist could have created their positive attitude while they managed to maintain a normal routine with their prosthetic rehabilitation. Additional factors that significantly affected the perceived functioning of the complete denture obturator were the prosthetic history of the participants and the status of the opposing mandibular dentition, findings similar to previous reports conducted in the general population [12,26]. Usually, when it comes to complete denture treatment the prosthetic history is directly associated with the success of the rehabilitation; therefore, since in the present study most participants had prior removable denture experience, the transition to the complete denture obturator prosthesis was smoother with more predictable functional and esthetic outcomes. However, the edentulous state of the mandible in certain participants complicated the prosthetic outcome since the fabrication of a complete denture obturator prosthesis with an opposing mandibular complete denture represents a unique challenge for both the patient and the maxillofacial prosthodontist [25].
Like the data of earlier studies in the general population, participants who received a Weber-Ferguson facial surgical approach, were more severely affected by their treatment since they had poor QOL scores and more problems when using the complete denture obturator prosthesis [21,27]. From a prosthodontic standpoint, the intraoral surgical approach, when possible, could enhance the prosthodontic rehabilitative outcome in patients with complete denture obturator prostheses [25]. On the other hand, the Weber-Ferguson facial surgical approach with the consequent facial scar and the contraction of the cheek is a more radical intervention that usually creates an extensive surgical defect that is more difficult to prosthetically obturate. Moreover, when operated extra orally and regardless of their older age most participants reported significant challenges with their appearance since the life-preserving surgical intervention can be life-changing creating visually confronting facial disfigurement and physical deformity, reduced self-esteem, and disturbed body image [28]. Consequently, recovery may be prolonged generating social anxiety and emotional distress resulting in psychosocial deficits, limited ability to engage in social relationships, isolation, elevated psychological disruption, and impaired QOL [28].
The adjuvant treatment modalities, similarly to previous reports conducted in the general population, were strong predictors of perceived obturator functioning since the post-radiation trismus and the associated lymphedema may significantly impair the stability and retention of the complete denture obturator prosthesis [10][11][12][13]. However, unlike  the same reports, administered adjuvant treatment did not alter the participants' QOL but affected their physical functioning, which was generally low even in those who underwent only surgical resection, probably due to their older age [10][11][12][13]. In the present study, older participants did not report significant post-radiation and/or post-chemotherapy side effects. This finding along with their already impaired physical status could probably explain their unaffected overall QOL. Most likely, in most participants, xerostomia was already established mainly due to their age and their additional medications for chronic diseases; therefore, radiation-induced xerostomia was not significantly addressed. Furthermore, since most participants were edentulous in both jaws and were wearing a set of complete dentures, the presence of highly polished, smooth, less abrasive, and easily cleaned acrylic surfaces that did not harbor fungus and bacteria significantly reduced the incidence of radiation and/ or chemotherapy-induced oral mucositis, fungal infections, and the associated pain.
Compatible with earlier studies, participants' comorbidities as interpreted by the ASA physical status significantly affected postoperative QOL since participants with severe systemic disease and ASA III index reported worse physical functioning and defective QOL [3,4]. They did, however, report improved eating capability with the complete denture obturator prosthesis since most likely the majority of participants with ASA III performance status were older with no significant social life and were already complete denture wearers, conditions that both contributed to a more unchallenging transition to the use of complete denture obturator prosthesis. The findings of the present study suggest that it is important to evaluate the relation between the extent of the disease, comorbid conditions, performance status, functional consequences, survival probability, and overall QOL in older patients requiring maxillectomy since older patients diagnosed with extensive tumors and poor anticipated postoperative survival might not benefit from radical ablative surgical resections. The constraints of this study involve the exclusion of participants with implant-retained complete denture obturator prostheses, the absence of objective measurements, and the insufficient evaluation of the psychological state of the older participants due to cancer-related anxiety and distress. In addition, since there are no earlier studies evaluating the challenges faced by older maxillectomy patients, the results of the present study were compared with the results of earlier studies conducted in the general population. Future prospective multicentered studies combining self-reported functional and psychological outcomes with clinical objective measurements to evaluate prosthesis functioning, as well as studies that compare implantretained with conventional prostheses should be planned.

Conclusions
Quality of life and maxillofacial prosthetic rehabilitation are closely interacting concepts when it comes to head and neck cancer experience. Older participants, who stated that their complete denture obturator prosthesis was functionally and esthetically effective, also reported improved quality of life. The perceived effectiveness of the complete denture obturator prosthesis depended on the surgical approach, the size of the resultant defect, the prosthetic history of the older participants, and the mandibular dentition. Although older participants with the severe systemic disease had worse QOL scores, they reported better-eating capability with the complete denture obturator prosthesis when compared to their peers with mild systemic disease.
Author contributions Dr. Artopoulou: Conception and design of the study, analysis of data, interpretation of data, drafting of the manuscript, and final approval of the version to be submitted Dr. Sarafianou: Acquisition of data Dr. Perisanidis: Critical revision Dr. Polyzois: Critical revision Data availability The data is available in the hospital's medical charts. The measurement instruments were described in the materials and methods section of the manuscript.

Code availability
The statistical package used is licensed at NKUA.

Declarations
Ethics approval The study protocol was approved by the ethics committee of NKUA (2015-268), in compliance with the Helsinki declaration and the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guidelines.
Consent to participate All the participants signed an informed consent before enrolling in the present study.