Introduction

The desire for a more youthful appearance has become increasingly evident, leading to a rise in the demand for aesthetic corrections, plastic surgeries, and treatments focused on orofacial synchronization. Among the procedures, bichectomy has stood out in recent years, gaining popularity due to its aesthetic results [1, 2].  This surgery is considered simple, aiming to reduce up to 40% of the volume of Bichat’s fat pad [3-5].  It enhances facial contours and narrows the face, impacting the volume of the middle third. In addition to its aesthetic benefit, bichectomy can be indicated for functional reasons; it is recommended for patients who suffer from chronic biting of the buccal mucosa, which can result in traumatic lesions in the area [6, 7].

Bichat’s fat pad has a pyramidal shape, and occupies areas, such as the buccinator, masseter, deep and superficial temporal regions, sphenopalatine, inferior orbital, and pterygomandibular regions [7, 8]. The Bichat’s fat pad, a part of adipose tissue and spherical in shape, is located between the buccinator and masseter muscles [9]. This structure is closely related to the parotid duct and the buccal and zygomatic branches of the facial nerve, and it is supplied by branches of the facial artery and vein. Therefore, despite being a simple procedure, it requires careful attention to avoid injury of important anatomical structures [4].

Although bichectomy is widely performed for its aesthetic benefits, it is essential to consider its potential functional implications on the stomatognathic system. The proximity of Bichat’s fat pads to muscles, such as the buccinator and masseter, along with their relationship with important neural and vascular structures, suggests that the removal of these tissues may impact functions beyond aesthetics. However, the international literature lacks studies that examine functional implications, particularly regarding muscular balance and masticatory function after the surgery.

Objectives

This longitudinal study aimed to analyze the pressure of the lips, tongue, and buccinator and orbicularis oris muscles at three distinct time points, i.e., before surgery and at intervals of 30 and 60 days after bichectomy. Additionally, the study sought to evaluate the distribution of occlusal contacts of the first permanent molars and dental arches in adult women who underwent bichectomy. The null hypothesis was that adult women who undergo bichectomy do not exhibit functional changes in orofacial tissues or alterations in the distribution of occlusal contacts.

Material and methods

This longitudinal study received approval from the Ethics Committee (protocol No. 10589419.0.0000.5419). All participants signed an informed consent form. The surgery for the removal of Bichat’s fat pads was performed at a specialized center in Ribeirão Preto, São Paulo, Brazil.

Sample size calculation was done using G*Power v. 1.9.2 software (Franz Faul, University of Kiel, Germany), employing an a priori test. Confidence level of 95%, effect size of 1.15, and test power of 90% were considered based on preliminary data regarding tongue pressure before and 60 days after bichectomy, where mean and standard deviation of tongue pressure were 52.2 (6.53) before the procedure and 51.2 (8.30) after 60 days. Based on these results, it was estimated that at least five partici­pants would be needed for the final sample of the study.

The study included 20 adult women, aged between 18 and 55 years, with a mean age of 31.1 years (± 9.8 years). All participants were indicated for bichectomy. Women who agreed to participate underwent dental evaluations for eligibility, including dental examination, assessment of the temporomandibular joint, and verification of aspects related to systemic health [1]. Inclusion criteria were the presence of all natural permanent teeth (except for third molars), normal occlusion, and the absence of signs or symptoms of temporomandibular dysfunction as per research diagnostic criteria for temporomandibular disorders (RDC/TMD) as well as other pathologies affecting the stomatognathic system. Age range and indication for bichectomy were also considered. Excluded were women with surgical contraindications, ulcerations, open wounds, skin allergies as well as those with cognitive, systemic, or neurological deficits or pathologies. Edentulous patients who used complete or removable dentures and those taking muscle rela­xants were also excluded due to the impact of these medi­cations on neuromuscular physiology.

After preoperative evaluation, patients received local anesthesia in the superior sulcus section, including the areas of premolars, molars, retromolar, and the buccal mucosa where an incision was made. The refe­rence point for locating Bichat’s fat pad was the papilla of the parotid duct, over which a Minnesota retractor was positioned to draw back the cheek, aiming to preserve the duct and reduce mucosal laxity in the incision area. The incision was made between the cusps of the first and second upper molars, extending 1.5 cm towards the second lower molar. Subsequently, the fibrous capsule of Bichat’s fat pad was incised with a scalpel, and the tissue was dissected and removed [10, 11]. In postoperative period, patients received prescriptions for antibiotics, anti-inflammatory medications, and corticosteroids. All followed the same surgical and medication protocol, according to techniques described in the literature [12, 13].

To analyze the pressure exerted by the lips, tongue, and buccinator and orbicularis oris muscles, the Iowa oral pressure instrument (IOPI; Medical, Redmont, WA, USA) was used. It was connected to a digital base using an 11.5 cm plastic tube and a 3.5 cm bulb filled with air, which transmitted pressure information to IOPI screen, allowing visualization of values obtained. Plastic bulb’s compression promoted the compression of air inside, enabling the device to record maximum pressure (kilopascals) produced during a voluntary isometric contraction of the orofacial tissues [14, 15].

The task protocol, describing the positioning and duration in seconds for pressure recordings of the lips, tongue, and buccinator and orbicularis oris muscles, was organized clearly. For the lips assessment, the bulb was placed between the upper and lower lips, with the teeth occluded and without sucking on the bulb, maintaining this position for three seconds. For the tongue evaluation, the procedure involved raising the tongue and pressing the bulb against the hard palate, also for three seconds. For the buccinator muscle, the bulb was positioned between the teeth and cheek in the molar region, for the same duration. Finally, the assessment of orbicularis oris muscle was done in the vestibule of the mouth for
3 seconds.

The analysis of occlusal contact distribution in the upper and lower dental hemiarches, both on the right and left sides as well as in the first permanent molars (16 and 26 for the upper, and 36 and 46 for the lower) was conducted using the T-Scan® III occlusal analysis system (Tekscan, Inc., South Boston, MA, USA) equipped with Windows-compatible software and sensors with a thickness of 0.102 mm. High sensitivity of the sensors ensured that there was no interference with natural bite, allowing accurate recording of occlusal contact dynamics. This precision enabled analysis of interrelationship of occlusal surfaces in terms of percentage force. During this procedure, participants remained seated with their torso and lower limbs forming a 90^o angle, and their heads supported [16]. The device was positioned so that the tip of the support was placed between patient’s upper central incisors. Collected data were stored and analyzed by the system’s software that displayed the maximum force of occlusal contacts as a percentage. After data collection, the Shapiro-Wilk normality test was conducted, indicating a normal distribution. Subsequently, data were subjected to statistical analysis using SPSS software version 20.0 (SPSS Inc., Chicago, IL, USA). Statistical analysis was performed using repeated measures ANOVA test, with significance level set at p < 0.05.

Results

Table 1 presents the data on the pressure of orofacial tissues (lips, tongue, buccinator muscles, and orbicularis oris) and the distribution of occlusal contacts of the first upper molars (16 and 26) and lower molars (36 and 46) of the right and left dental arches. No significant differences were found in the pressure of orofacial tissues between the evaluated time intervals. The numerical data from the study indicated an increase in the pressure of the tongue and lips after 60 days, with a gradual increase in the buccinator and orbicularis oris muscles. In the analysis of the teeth, the 16 tooth exhibited a decrease in force at 30 days, with recovery by 60 days, while the 26 molar showed a gradual increase. The 36 tooth indicated an increase at 30 days, but decreased by 60 days, whereas the 46 molar demonstrated a gradual decrease. The distribution of forces in the dental hemiarches remained stable.

Discussion

According to the statistical results of the study, the null hypothesis was accepted, showing that bichectomy in adult women does not induce significant changes in the pressure of orofacial tissues or modify the distribution of occlusal contacts of the first permanent molars and dental hemiarches. Therefore, this longitudinal study confirms that the procedure does not negatively impact orofacial functioning.

Although bichectomy is an aesthetic intervention aiming to contour the cheeks and narrow the middle third of the face, some outcomes indicate that it may promote minimal functional modifications that are clini­cally relevant to the stomatognathic system [1]. However, in this study, no significant differences were found in the pressure of the lips, tongue, buccinator muscles, and orbicularis oris or in the distribution of occlusal forces. Different variations in the results observed over time, particularly in terms of gradual increase in the tongue and lip pressure, suggest physiological adaptation in postoperative period [17], which deserve consideration.

The pressure of the lips and tongue demonstrated a gradual increase at 60 days after bichectomy, and can be explained by muscular physiology and adaptation to the new facial contour. Partial removal of Bichat’s fat pads changes volumetric proportion of the face, softening its contours and potentially influencing the functional dynamics of adjacent tissues, such as facial musculature and subcutaneous adipose tissue [18]. These encapsulated adipose structures located in the cheeks play essential role in the protection and smooth gliding between muscle layers [19]. The intervention may modify the function of buccinator muscle responsible for maintaining adequate tension in the cheeks. This modification, in turn, can impact the functioning of orbicularis oris muscle due to direct anatomical relationship between these two facial muscles, as their muscle fibers form a functional unit known as the buccinator mechanism [20]. Thus, the procedure of Bichat’s fat pad removal is not limited to changing facial aesthetics, but may also interfere with the tone and overall function of facial musculature [21].

These adaptations are also justified by muscular plasticity that refer to the ability of muscles to adjust to new conditions of load and function imposed by local trauma resulting from extraoral or intraoral factors. This can lead to changes in both the architecture and functioning of the muscles [22]. At 60 days after bichectomy, the body begins a process of physiological tissue remodeling, primarily regulating blood flow, during which the muscle fibers may increase their strength and endurance [23]. This process is mediated by the activation of cellular signaling pathways, promoting protein synthesis and regeneration, and resulting in physiological readjustment [24] that can modify both the efficiency of orofacial tissues and facial aesthetics. This underscores the importance of the lips, tongue, buccinator muscles, and orbicularis oris in reconfiguring facial dynamics.

The tongue and lips, as highly adaptive structures, may increase their pressure as a form of functional compensation, seeking to restore orofacial balance. The lips, due to their primary role in sealing the oral cavity and phonation [25], are particularly sensitive to modifications in muscle tone, shape, and facial aesthetics [26], which could explain the progressive increase of their strength over time.

The buccinator muscles, playing a role in maintaining the shape of the cheeks and controlling salivation [27], showed a gradual increase in the pressure in the cheek area 60 days after the surgery, although this increase did not reach statistical significance. Anatomi­cal position of the buccinator and masseter muscles in relation to Bichat’s fat pad located between the anterior border of the masseter and buccinator, shows an average volume variation of 7.8-11.2 milliliters for men and 7.2-10.8 milliliters for women, with an average thickness of 6 millimeters [28]. This may help explain the increase in pressure of the buccinator muscles after bichectomy, as the removal of adipose tissue can modify the space between the buccinator and masseter muscles, resulting in greater compression and tension during the masticatory process and other orofacial functions [29].

The distribution of occlusal contacts in the upper permanent molars (16 and 26) and lower molars (36 and 46) demonstrated no significant differences over the analyzed periods. However, the percentage patterns revealed small variations in the numerical data, which can be considered for clinical analysis. Tooth 16 showed an initial reduction in contact force, followed by an increase after 60 days, while tooth 26 exhibited a gradual increase in average force. Tooth 36 demonstrated an increase at 30 days but returned close to its initial value at 60 days, whereas tooth 46 showed a gradual decrease.

Changes in muscle tone or function resulting from surgical procedures can impact, even subtly, the function of human body [30]. In the stomatognathic system, these modifications can be accurately monitored using specific instruments, such as T-Scan. By recording the center of force (the first point of contact) and maximum intercuspation, this tool is effective in evaluating postoperative occlusal changes [31].

These variations can often be attributed to the need for functional adjustments arising after surgeries, which alter biomechanics of human facial movements. According to an international study, the surgery of Bichat’s fat pad removal impacts functioning of the stomatognathic system, providing insights into functional recovery in postoperative period and possible compensatory adaptations [1].

Although primary aim of bichectomy is not altering dental occlusion, the resulting muscular adaptation may lead to temporary adjustments in the forces exerted by the teeth during masticatory function [32]. The literature suggests that mastication, mandibular posture, and occlusion are interconnected with muscle function and pressure of intraoral tissues [33].

After bichectomy, there may be a slight redistribution of masticatory forces, attributed to anatomical relationship between the masseter muscles and Bichat’s fat pad [28]. The removal of Bichat fat pads may result in a temporary adjustment in the control of mandibular movement due to the function of the involved muscles, especially the masseter. This can explain slight variations in the distribution of occlusal contacts of the first permanent molars following intraoral surgical procedures. Although not statistically significant, this phenomenon may be related to muscular adaptation, where the masticatory system seeks to restore functional balance [34].

Furthermore, it is important to emphasize that changes in muscle pressure, such as that of the buccinator, resulting from surgeries involving orofacial soft tissues, could also influence – albeit subtly – the occlusion of the first permanent molars. These modifications in muscle pressure have the potential to interfere with the stability of forces applied to the teeth, altering the occlusal relationships [35].

The buccinator muscle plays an essential role in maintaining the position and balance of dental arches, as it exerts lateral pressure on the cheeks. As part of the lateral wall of the oral cavity, it helps keeping the food bolus in position during chewing. This action may lead to thickening of the cheeks, which can in turn exert pressure on the alveolar bone, contributing to changes in dental occlusion [36].

The absence of significant changes in the distribution of occlusal contacts in the right and left dental hemiarches, reinforces the idea that buccal fat pad removal does not compromise the overall occlusal stability, which is a promising aspect, especially in clinical context. However, the observed variations, even without significant differences in the pressure of the lips, tongue, buccinator muscles, and orbicularis oris muscle, indicate that adult women may undergo a period of functional adjustment. This suggests the importance of postoperative follow-up, including guidance in physiological exercises that may aid in functional recovery.

Although the statistical results did not demonstrate significant differences in the current longitudinal study, the numerical variations observed over time indicate interesting outcomes for the stomatognathic system. The interpretation of these clinical data is important, as fine changes in orofacial dynamics may impact patient recovery. Therefore, considering both statistical and clinical outcomes is essential for a comprehensive understanding of the consequences of buccal fat pad removal.

The limitation of this study include its small sample size, consisting exclusively of adult women, thus limiting generalization of the results to other populations, such as men or individuals of different age groups. Additionally, follow-up was restricted to 30 and 60 days post-surgery. Future studies with longer follow-up may provide much more detailed information about the muscle adaptation process over time. Another limitation to consider is that the study focused on the functional analysis of orofacial tissue pressure and distribution of occlusal contacts, and did not evaluate other functional aspects, such as chewing and phonation, as these could have provided a broader view of implications of buccal fat pad removal on orofacial function.

However, these limitations do not weaken the clinical relevance of the study, even in the absence of sig­nificant differences, highlighting the need for further investigation of functional impacts of buccal fat pad removal.

Future research should include longer follow ups and more diverse samples to determine whether the observed functional modifications progress or stabilize over time. Additionally, studies that examine additional clinical aspects, such as masticatory efficiency, phonetics, occlusal stability, and potential postoperative rehabilitation needs, may help guide more comprehensive care protocols for patients undergoing bichectomy.

Conclusions

In the study, although no significant differences were observed in the pressure of orofacial tissues or in the distribution of occlusal contacts following buccal fat pad removal, functional modifications occurred in the orofacial system. There was a gradual increase in the pressure of the lips, tongue, and muscles, indicating muscle adaptation. Some variations in occlusal contacts were noted, but without clinically relevant impact. These results underscore the importance of postoperative moni­toring, suggesting that postsurgical recovery should consider these adaptations to ensure satisfactory long-term outcomes and patient satisfaction.

Disclosures

Author contributions: Conceptualization: P.L.S.L., A.H.L.S.C., S.S., S.C.H.R.; Methodology: P.L.S.L., A.H.L.S.C., S.P.X., S.S., S.C.H.R.; Investigation and data collection: P.L.S.L., A.H.L.S.C., S.S., S.C.H.R.; Formal ana­lysis: M.P., S.S., S.C.H.R; Data curation: P.L.S.L., A.H.L.S.C., M.P., S.S., S.C.H.R; Writing of original draft: P.L.S.L., M.P., S.C.H.R.; Writing – review and editing: S.P.X., S.S.; Supervision: S.C.H.R.; Project administration: P.L.S.L., A.H.L.S.C., S.S., S.C.H.R. All authors have read and agreed to the published version of the manuscript.

Funding: This research received funding from FAPESP and National Institute and Technology – Translational Medicine (INCT.TM) .

Institutional Review Board statement: This study was approved by the Ethics Committee of the Ribeirão Preto School of Dentistry, University of São Paulo, Brazil (approval number: 10589419.0.0000.5419 issued on 8 April 2019).

Informed consent statement: Informed consent was obtained from all subjects involved in the study. Written informed consent has been obtained from the subjects to publish this manuscript.

Data availability statement: The original contributions presented in this study are included in the article. Further inquiries can be directed at the corresponding author.
The full study protocol is available from the corresponding author upon reasonable request.

Acknowledgments: None.

Conflicts of interest: The authors declare no conflicts of interest.

AI use statement: No artificial intelligence tools were used in the preparation of this manuscript.

References