Pre and post-surgical management of palatal perforations with obturator prostheses: description of a new classification, a modified operative protocol, and a new evaluation test.

Introduction

Palatal perforations are lesions establishing a communication between the oral and nasal or sinus cavities, compromising vital functions such as nutrition and speech. A palate opening permits access of food and fluids to those cavities, encouraging organic stagnation and subsequent microbiological contamination. Consequently, patients may experience an unpleasant odor or taste, as well as an increased risk of respiratory infections or complications. Moreover, the physiological interaction between the soft palate and adjacent anatomical structures may be altered, leading to nasal emission, speech impairment, and other phonetic dysfunctions [1].

Palatal perforations’ causal phenomena include malignant lesions in the palate, substance abuse (cocaine), orofacial clefts, traumas (as gunshot injuries), Wegener’s syndrome, or infections [2–4] (Figures 1 and 2).

Every phenomenon determines specific features in the involved tissues, thereby conditioning the lesion’s clinical management and subsequent treatment. For instance, radiotherapy may stiffen tissues [5], while cocaine abuse may lead to necrosis and ulcerations, utterly complicating the pathological picture [6]. It is therefore fundamental to understand the etiology of the perforation to manage it and to plan effective prosthetic rehabilitation, since tissues vary in appearance and dynamics according to the pathology.

In rehabilitation, it is essential to consider psychological factors alongside clinical ones. Patients with oncological pathologies affecting the face or with orofacial clefts may face obstacles to their acceptance of their physical image [2]. At the same time, the subjects with a history of cocaine abuse may show depression, low self-esteem, and post-traumatic stress disorders [3–4]. Hence, a complete rehabilitative approach must aim to ensure the patient’s physical and psychological well-being. The rehabilitative approach described in this work is represented by obturator prostheses and devices such as upper mobile prostheses, aimed at functional and aesthetic restoration through lesion coverage.

Palatal obturators have been described and applied to treat perforations for centuries, a remarkable time span during which their shape and materials have evolved significantly to improve stability and comfort.

The ultimate publications present many options for palatal obturator design, addressing the materials employed (silicon, metal alloys, and polyether ether ketone) [7–8] and the fabrication techniques (traditional or digital). Rigid materials offer good mechanical performance but may cause unease and ulceration, whereas softer ones are more prone to deterioration [9]; prosthetic surfaces need to reduce fluid retention to prevent infections. Implant rehabilitation may increase prosthetic retention [10–11], but requires an accurate preliminary evaluation of the patient’s tissues and personal preferences.

One of the most frequently encountered obturator shapes includes a bulb to be introduced into the lesion. The bulbs are prosthetic portions that fill the lesion and protrude into the nasal cavity, directly contacting the palatal tissues. Their addition to the structure aims to improve prosthetic retention phonetics; however, their presence may facilitate the retention of food debris and nasal fluids, increasing the risk of infection and foul odors [12]. In fact, the space occupied by the bulb is physiologically patent to ensure airflow for breathing and speaking; the Authors believe this volume change may also lead to functional alterations. Moreover, according to the authors’ experience, pressure bulbs applied to fragile lesional tissues may also impede recovery and cause discomfort, especially in severe or posterior lesions. Obturators may also be required by oral surgeons when planning surgical closure of the perforation; in these cases, the possible enlargement of the fistula due to the bulb’s presence may obstruct the final result.

Obturators’ design is often based on the Aramany classification, which identifies six categories of lesions according to the perforation’s placement and the remaining teeth [13–14]. This and other more recent similar classifications [15–34] do not include all potential causes of palate perforations, such as cocaine abuse or trauma, and dental or implant anchorage is also not considered. One of the most recent and interesting classifications is the one proposed by Alqarni et al. [35], which takes into account the horizontal and vertical components of the defect. In the section dedicated to the horizontal components, each of the seven groups describes the defect’s position and the remaining edentulous area. In contrast, the four classes of the second section involve the vertical extension of the maxillectomy performed.

This work uses the Mascolo-Eramo (ME) classification, which provides the clinician with a broader picture of treatment options, including total edentulism and perforations from causes other than the maxillectomy procedure. This categorization takes into account the presence (or absence) and distribution of prosthetic anchorage fixed pillars (such as teeth or dental implants) in the oral cavity, then describes three classes (Figure 3):

1. I Class: absence of pillars
   • Ia) with perforation on the palate
   • Ib) with perforation on the side of the palate,
2. II Class: one-sided presence of pillars
3. III Class: presence of pillars on both sides, with the subsets
   • IIIa) with perforation on the palate
   • IIIb) perforation in the palate’s anterior portion.

This classification evaluates the prosthetic appliance’s stability, which increases from the first to the third class and can be applied to every type of palatal perforation, regardless of the cause.

This work also aims to present a new questionnaire, the Mascolo Questionnaire (QM) (tab. 1–4), for evaluating the aforementioned devices.

The QM investigates all of the oral functions, such as mastication (Tab.1), speech (Tab. 2), prosthetic seal and swallowing (Tab.3) and comfort (Tab.4). The section dedicated to mastication draws up a list of Mediterranean diet food, and including dishes with different consistencies, such as meat, which is represented as steaks or hamburgers (respectively of harder and softer consistence) (Tab.1). As long as speech is phonetics is concerned, speech comprehension is subdivided into three categories according to the percentage of understood words: 80–100%, 50–79% and less than 50% (Tab 2 phonetics evaluation). Swallowing phase performance is evaluated based on the frequency of accidental fluid ingestion during the process (Tab. 3, Seal and Swallowing evaluation). The last section is dedicated to patients’ acceptance of the prosthesis, especially comfort during use (Tab. 4).

Materials and Methods

The population in this study comprises 40 patients aged 31 to 82 years (32 men and 8 women) from the GIPO (Gruppo Inter-disciplinare Patologie Oncologiche, Oncological Pathologies Interdisciplinary Group) Unit at San Filippo Neri Hospital, Rome. These patients were affected by lesions following maxillectomy (34 subjects) and substance abuse (6 subjects) and were previously treated with bulb obturator prosthesis. The inclusion criteria adopted were: non-progressive oncological pathology in the post-maxillectomy cases, stable health condition, presence of at least 10 teeth in the inferior arch, absence of active periodontitis, presence of teeth from the canine to the first molar on the side opposed to the one interested by the maxillectomy procedure (for one-sided maxillectomy cases) or at least two molars on each side (for anterior maxillectomy), mediterranean diet.

Patients with progressive oncological pathology, polymorbidities, active periodontitis, fewer than 10 teeth in the inferior arch, or those who had undergone an implant surgical procedure, due to the consequent differences in prosthetic stability, were excluded from the study.

Before the treatment, patients completed the QM Questionnaire, and their responses were recorded by nursing staff who did not participate in the study.

The first step of the protocol is the analysis of the clinical case, which comprises anamnesis and dialogue with the patient, physical examination of hard and soft tissues with measurement of the lesion, evaluation of radiographs, and collection of first alginate impressions and photographic evidence. First impressions are needed to study the case and to build an individual impression tray. Alginate as the impression material is preferred to other instruments of recent introduction, such as oral scanners, since their type of image acquisition and the algorithms leading to their data elaboration may produce errors or imprecision in the more extended scanning, with repercussions on the final result when realizing bigger prosthetic works [36–39]. Afterward, impressions are cleaned of salivary remnants, cold-sterilized, and sent to the technician laboratory, where they are duplicated in silicone materials and poured in class III stone within 12h of registration. For individual impression tray creation, alginate insulation is applied to the model cast. Its perimeter is drawn in the model, including the vestibular fornix and the palatal portion affected by the lesion. For individual impression tray construction, both self-curing and light-curing resins can be used.

During the second appointment, the clinician evaluates the lesion and the state of tissues and records the maxillary position with the facebow. New dental impressions with the individual impression tray are also taken to obtain the master model in III class stone, on which the lesion’s dimensions and future device planning are drawn. In extended rehabilitation, the facebow registration can be used. When the perforation affects even the soft palate, resin is added to the individual impression tray directly in the patient’s oral cavity to produce a firm support for the impression material, to detect velum, and then build a palatopharyngeal obturator correctly.

The lesion’s area on the stone model is filled with wax to simulate a healthy palate. Afterward, a dental baseplate with an occlusal registration rim is built with self- or light-curing resins. In partial dentures, the original vertical dimension of occlusion isn’t altered; therefore, stainless steel hooks are applied to achieve better plate stability during prosthetic tests.

In complete edentulism, instead, a wax rim reaching a height of 2,2 cm in the anterior area is applied. The upper plate also helps detect the maxillary position with the facebow.

The master model and antagonist are mounted in the articulator along with the baseplate and rim. Dental elements for the test are applied to the baseplate. They can be pre-formed in three or four-layer resin, commercially available, or produced in PMMA in the technician’s laboratory.

During prosthetic tests, before introducing the obturator into the oral cavity, resin and wax plates need to be cold-sterilized to avoid the spread of bacterial and viral loads from the technician’s lab to frail patients. In this work, cold sterilizers based on reducing free radicals (Ec-Ster - Icm S.r.l-Italy) have been employed since they can sterilize surfaces in an extremely short time, less than 1 minute, without compromising prosthetic materials or irritating the mucosae. Similarly, after the tests, the plates have been cleaned with water and cold-sterilized to avoid contamination of the technician’s lab with the oral bacterial load. During device testing, the clinician checks for complete lesion coverage by the device. In partial edentulism, must occlusal contacts on prosthetic teeth be grazing? Lateral loads need to be accurately evaluated to avoid excessive stress on the mucosa, which can lead to ischemia. In dentistry, medical kinesiology (KMOA) techniques are employed to determine the correct vertical dimension. KMOA is a clinical practice used to assess masticatory muscle posture by eliciting crossed reactions with other muscles; the clinician may then collect reliable information on the mandibular position in the three spatial planes within the patient’s tolerance range. At the same time, these techniques help the clinician determine whether the patient can accept the device’s size.

During prosthesis finalization, the master model with the product is placed in the muffle furnace mold, and the countermold is formed. Wax on the lesion’s area is removed and replaced with light-curing filler (or further wax) to create and keep space during the first phase in the muffle furnace. These materials are removed after the hard resin has been baked and replaced with a softer resin. A traditional resin (harder and more consistent) is injected and then baked. Once the baking has ended, the muffle furnace is opened, and the material portions previously inserted to maintain spacing are removed. On the lesion’s borders, more flexible materials such as Flexacryl (Lang Dental IL USA), an acrylic bicomponent resin of softer consistency, Molloplast-B (Detax GmbH & Co. KG - Germany) (a mono-component material on a silicon base), Soft Liner (GC Corp., Japan) (bicomponent acrylic), or Permaliner (Detax GmbH & Co. KG - Germany) (silicon material) are applied. These materials have different hardness levels and are selected by the clinician according to the patients’ and their tissues’ needs. In the authors’ experience, Flexacryl and Molloplast-B are designated for tumors and clefts. At the same time, tissues with decreased or remarkable sensibility (such as mucosa exposed to cocaine’s irritating stimulus) are treated respectively with Soft Liner and Permaliner. Anyway, before positioning the soft resin in the muffle furnace, thick pieces of material are placed in the spaces adjacent to the lesion to avoid harmful compression of the tissues. Measures selected for these pieces’ apposition space in a range of 3 to 7 mm of extension next to the lesion, with a thickness ranging from 1 to 1,5 mm in undercut areas. These values refer to complete or partial obturator prostheses based solely on mucosal support, thereby causing greater compression of tissues; in cases of dental support, this value decreases, ranging from 0,5 to 1 mm in undercut areas (III Class). In palatopharyngeal obturators, the lesion’s covering material has to be as elastic as possible to guide the velum’s movement during deglutition.

When the second phase of baking is finished, the muffle furnace is opened, and the device is refined and polished. Anchorage or retention elements are built in stainless steel. These hooks can be double (0,7 mm in diameter), n°1, gingival (0.9 mm), or round for occlusal passages (0.8 mm). If dental elements need to be added to artificial teeth in commerce or in PMMA (through digital workflow), they are available. If an increase in the vertical dimension is needed and natural teeth are present, it is preferable to cover them with the cover-up technique, build the PMMA crowns using a digital workflow, and achieve reliable anchorage and a more appropriate vertical dimension.

When delivering the final device, it is once more cold-sterilized, and occlusal and aesthetic control are performed. Instructions on hygiene, cleansing, and maintenance procedures for the prosthesis are given to patients scheduled for follow-up appointments at 2, 5, 15, 30, 60, and 90 days. During the follow-up appointments, the clinician verifies the absence of new mucosal lesions, especially on the tissues adjacent to the perforation, checks the device for possible surface encrustation (indicating a lack of proper maintenance by the patient), and tests the stability of occlusion and its acceptance by the patient’s neuromuscular system with kinesiological tests.

After three months, the QM Questionnaire was administered again to patients by the sanitary staff who had not participated in the study. The Sato questionnaire for prosthetic functionality [40] and its subsequent modifications have not been used, as they consider only masticatory ability and pose an excessive number of questions about foods exclusively from the Japanese diet. The chosen questionnaire is the Mascolo Questionnaire, as it addresses all aspects of oral function and consequently provides a broader picture of the prosthesis’ efficacy with a simple configuration, thereby avoiding excessive time for result registration.

Results

The results of the Mascolo questionnaire, administered before and after implantation of the new obturator in the 40 patients involved, are shown in Table 5 (Mastication), Table 6 (Speech), Table 7 (Prosthetic Seal and Swallowing), and Table 8 (Comfort).

For the statistical analysis, the Wilcoxon signed-rank test was used to assess statistically significant differences in questionnaire responses between pre- and post-use of the new obturator. This nonparametric test was selected due to the ordinal nature of the questionnaire items and to avoid assumptions about the underlying data distribution, especially given the relatively small sample size. Statistical significance was set at p<0.02. Statistical analyses were carried out using the Stata software, version 15 (Stata Corp. 2015. Stata Statistical Software: Release 15. College Station, TX: Stata Corp LP). Statistical results can be found in tables 9–12.

The analysis of the collected data shows a statistically significant difference (with a marked increase in positive patient evaluations) between responses to the Mascolo questionnaire before and after treatment, with a significance level of p < 0.02.

Discussion

Obturator prostheses represent a rehabilitative option and aim to restore daily functions such as chewing, swallowing, and speaking, as well as aesthetics and comfort, but only if well-made. If patients use uncomfortable and poorly appreciated prostheses, they are exposed to worsening of lesions and to diseases “ab ingestis”.

The results obtained in our clinical trial seem to statistically demonstrate the effectiveness of the presented workflow for constructing effective obturators because they are designed and made in a personalized way:

• Mascolo-Eramo classification supports clinicians in quickly developing an effective description of the lesion, regardless of the pathogenesis. Communication among all staff members involved is then simplified, with positive consequences for the final result. The protocol described here leads to prostheses that respect the anatomical structures involved and harmoniously cooperate with the functions requiring assistance.
• The four macro arguments faced by the QM questionnaire offer clinicians a complete evaluation of the device delivered to the patient, analyzing the satisfaction with its use. The differences found in the answer given to the questionnaire before and after the treatment show the progress found in the prostheses ’use and acceptance when created following this protocol.

Conclusions

In conclusion, the workflow presented here, including all the tools introduced, appears to lead to the creation of efficient and com fortable obturators that positively affect patients’ psychophysical well-being and, therefore, their quality of life.