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The epithelial-myoepithelial carcinoma (EMC) is a rare neoplasm of the salivary glands with an incidence

Lip carcinoma is one of the most frequent conditions affecting the general population. It is among the ten most common neoplasms, but despite advances in research and therapy, its prognosis has not improved in a significant way in the past few years, making it a challenge in the medical research field and in surgical treatment. This study was conducted with the aim of evaluating the available reconstructive surgical options for the treatment of lip carcinomas in order to define which could be the most appropriate technique to achieve satisfying aesthetic and functional outcomes considering hospital resources in the COVID-19 era. Seventeen patients were included in this retrospective study, which took place between January 2019 and April 2021. There were two groups: seven patients who underwent a radial forearm free flap and ten who underwent locoregional flaps. The statistical analysis was performed to evaluate four different endpoints. Surgical length, ICU stay, and hospitalization time were minor for locoregional flaps. There was no statistically significant difference between the two groups when considering post-operative complications. Locoregional flaps have a more aesthetically pleasing result, but from a functional point of view, the results can be superimposable. Both techniques are associated with adequate speech, mouth opening, sealing, and symmetry. Given the impact of the COVID-19 pandemic on the healthcare system, locoregional flaps have been proven to be a good surgical option in the reconstruction of lip defects both in terms of aesthetics and functional outcome.

Abstract BackgroundNonsurgical nasal reshaping (nSNR) with hyaluronic acid (HA) filler is a well-established procedure performed to ameliorate nasal appearance and is considered a valid alternative to surgical rhinoplasty in selected patients. ObjectivesThe aim of our study is to evaluate the decision-making process and management of patients undergoing rhinoplasty, with previous HA filler injection, and evaluate if consensus could be achieved to recommend guidelines. MethodsBetween April and May 2021, an online survey was sent to 402 Italian surgeons of different specialties. The survey collected information regarding the types of treatment of patients who have previously undergone nSNR, who should undergo surgical rhinoplasty. For those surgeons using hyaluronidase, an additional information was collected. ResultsIn a range of time of 2 months (April and May 2021), a total of 72 surgeons replied and completed the survey: out of the 402 questionnaires sent, the response rate was approximately 18%. The majority of respondents (61.5%) replied to inject hyaluronidase (HYAL) in patients who had to undergo a rhinoplasty but reported previous nSNR. Of the surgeons who use HYAL, 70% performed rhinoplasty after a waiting time of 3 to 4 weeks. ConclusionsEither direct surgical approach or hyaluronidase injection first seems to be a viable options. The use of HYAL before surgery is the choice with the broadest consensus in our survey. However, a larger case-control study with long follow-ups is necessary to understand if in patient seeking surgical rhinoplasty who already received nSNR, the injection of hyaluronidase before surgery is mandatory, recommended, or not.

Abstract Background To evaluate the viability and efficacy of sialendoscopy for the management of parotidomegaly related to eating disorders, 6 patients suffering from eating disorders and recurring symptoms of glandular swelling were followed up at the Multidisciplinary Department of Medical-Surgical and Dental Specialties, Oral and Maxillofacial Surgery Unit, AOU University of Campania “Luigi Vanvitelli”. After the detection of the impaired gland through clinical and radiographical analysis, the diagnostic unit was introduced into the duct and was advanced in, reaching the ductal system. Plaques were washed out, any strictures were dilated both by hydrostatic pressure application and steroid solution injection directly in the fibrotic area. Results Both glands resulted affected in 83% of patients. 11 parotid glands were explored and treated. Strictures were found in 2 glands (33%), sialectasis in 3 glands (50%), strictures and sialectasis together in 1 glands (17%). In 3 parotid glands (50%) Stenon’s duct was affected, in two (33%) only secondary ducts, in 1 (17%) both. We reached symptomatic improvement in 5 patients (83%), reporting the spherical volume of the parotid region and pain reduction. Conclusions Our results demonstrate that sialendoscopy is a safe and effective therapeutic method to treat EDs salivary symptoms. Treating the underlining psychiatric pathology should be the primary goal in patient care to lower the possible recurrence rate and increase the successful outcome of this technique.

Background: Nowadays, the incidence of skin cancer has increased, especially in the elderly population, probably due to increasing longevity and lifestyle changes. Sun exposure plays a pivotal role in the development of the skin tumors, among these basal cell carcinoma (BCC) is the most frequent with an incidence 4 times higher than that of squamous cell carcinoma (SCC) and it is 20 times more common than melanoma. On the other hand, skin adnexal tumors are extremely rare and hydroadenocarcinoma (HC) is generally considered a malignancy of eccrine cutaneous sweat glands. It occurs in 0.01% of skin cancers and often it can mimic other skin cancers, particulary BCC. Case presentation: An 84-year-old woman come to our attention for a neoformation on the upper lip. Seeing as she had previously undergone operations for removal of basaliomas on the face, the lesion was believed to be a recurrence. Facial and neck MRI and CT-scan analysis revealed that the lesion appeared in correspondence of the midline and paramedian site of the upper lip with extension into the left nasal cavity, not dissociable from the surrounding tissues. For this reason, the patient underwent an “en bloc” resection instead of Mohs' surgery. The definitive histological diagnosis concluded that the lesion was a hydroadenocarcinoma. Conclusion: In front of a nodular lesion of the skin it is always advisable to perform a biopsy to type the neoformation and also exclude rare tumors such us hydroadenocarcinoma.

(1) Background: Extrapleural solitary fibrous tumors (ESFTs) are rare oncological entities occurring in the head and neck, and even more so in the salivary glands. The clinical presentation and histologic features are usually unspecific, resulting in frequent misclassification. As an unusual tumor, ESTFs have an unpredictable clinical behavior. (2) Methods: We present two clinical cases referred to our Maxillofacial Surgery Unit for the onset of a symptomless mass involving, in one case, the parotid gland, and in the other case, the sublingual gland. (3) Results: Solitary fibrous tumors could be considered as neoplasms with intermediate biological behavior that are not entirely predictable on the basis of morphological features, as these are mostly still unknown. However, a few histologic, immunohistochemical, and imaging features, such as a hypodense signal at the T1 sequence in an MRI, or positivity for CD34, bcl2, and CD99, and the NAB2-STATS6 fusion gene, could be useful for an early differential diagnosis of ESTFs. (4) Conclusions: All patients were alive at follow-up with no evidence of disease. Surgical management should always be considered as the first choice for oncological radicality, and clinical behavior should always be defined with the help of the study of radiological and anatomopathological features.

Introduction. Orofacial reconstruction plays an important role in the treatment of patients affected by oral and maxillofacial cancers. Improvements in technologies and studies of biomaterials have widely expanded surgical possibilities to achieve good functional and aesthetic outcomes. By the way, xenografting procedures gained great consensus in the last decades, because of their documented reliability and efficacy. We present a case of anterior maxillary chondrosarcoma (CHS) that has undergone surgical ablation followed by reconstruction with an equine-derived bone xenograft. Case Presentation. A 68-year-old woman affected by CHS of the premaxilla underwent surgical ablation involving the four incisors followed by reconstruction using an equine-derived bone substitute. Bony reconstruction was planned to achieve implant and dental prosthetic rehabilitation at a second surgical time. Primary surgery was carried out without complications. Good integration of the graft was confirmed by radiological examination. At 12-month follow-up, the patient refused the implant placement and spontaneously adopted a mobile prosthesis. One year later, plates and screws were removed, because of the exposure of a titanium plate. The graft was finally rejected within 3 weeks. Discussion. Nonantigenic equine-derived biomaterials have shown reliability and a good safety profile. In the presented case, implant insertion should have been performed 12 months after the primary surgery. During the follow-up, until dental mobile prosthesis was applied, clinical and instrumental examinations demonstrated a good integration of the graft. We suppose that a chronic inflammation of the mucosa led to the exposure of the plate, perhaps due to pressure, minimal movements, or imperfect fitting of the mobile prosthesis. Removal of fixation means was performed to prevent grafting failure, without success. On the other hand, missing load could induce the graft to act just like a prosthesis, without a real process of integration. Safety and reliability of equine-derived bone xenografts cannot be currently confirmed if not followed by implant insertion and dental rehabilitation.

Salivary gland disorders are uncommon in children; they show a lower prevalence when compared to adults. The literature has a relative lack of information about the management and the different treatment protocols regarding these diseases. The aim of this research is to investigate the prevalence of both benign and malignant salivary gland disorders, focusing on diagnostic and therapy. An audit of patients diagnosed with salivary gland disorders was conducted from 2000 to 2020. 99 patients’ records were selected and analyzed: 51 males’ and 48 females’, age 10 ± 4 SD. Obstructive pathologies were the most frequently diagnosed (49 patients) followed by oncologic (21 patients), inflammatory (20 patients), rheumatologic (4 patients), malformative (3 patients) and infective disorders (2 patients). The parotid was the most affected major gland in 47 cases with a prevalence of diagnosis of juvenile recurrent parotitis (JRP) (40.4%), followed by the sublingual gland in 14 cases of ranula (100%) and the submandibular gland in 11 patients suffering from sialolithiasis (84.6%). Swelling was the most common symptom (75.7% of patients). Seven different neoplasms were documented. A greater prevalence of low-grade mucoepidermoid carcinoma among the malignant group (38.1% of oncologic cases) was noted. In regards to benign tumors, pleomorphic adenoma was the most common diagnosis (47.6% of cases). The symptoms and outcomes showed statistical significance concerning gender. Although salivary gland diseases in children and adolescents are rare, it is essential to observe and monitor all of the symptoms to intervene if necessary, as painless swelling is a symptom common from both benign and malignant diseases.

Temporary facial nerve palsy after parotid tumor surgery ranges from 14 to 65%, depending on surgery, tumor type, and subsite. The study aimed to evaluate the role of Kabat physical rehabilitation in the outcomes of patients affected by severe facial nerve palsy following parotid gland surgery. The results and clinical data of two groups, Kabat and non-Kabat (control), were statistically compared. Descriptive statistics, the multiple linear regression model, difference in difference approach, and the generalized linear model were used. F-Test, Chi-square test, McFadden R-squared, and adjusted R-squared were used to assess the significance. The results showed that the House–Brackmann (HB) stage of patients who had physiotherapy performed were lower than the control group. The decrease of HB staging in the Kabat group at 3 months was −0.71 on average, thus the probability of having a high HB stage decreased by about 13% using Kabat therapy. The results are statistically significant, and indicated that when the Kabat rehabilitation protocol is performed, mainly in the cases of a high-grade HB score, the patients showed a better and faster improvement in postoperative facial nerve palsy.

The “Vaccines and Related Biological Products Advisory Committee 17 December 2020 Meeting Briefing Document”, formulated by the FDA, reported three cases of swelling in areas previously injected with HA filler, introducing the possible relationship between a COVID-19 vaccine and adverse events in areas previously injected with HA fillers. The aim of this research is to report a case of an adverse event following a COVID-19 vaccine in a patient previously injected with facial filler. Furthermore, a scoping review on the same topic was performed. The research was carried out on the electronic databases PubMed, Cochrane Library, Web of Science, Google Scholar and Scopus. The selection process identified four articles as eligible for inclusion in the review. Nineteen patients, including the described case report, who experienced an adverse event following a COVID-19 vaccine in areas previously injected with facial filler were identified. Adverse events following a COVID-19 vaccine in patients previously injected with facial filler appear to be rare. A high BDDE cross-linking rate and/or a low-molecular-weight hyaluronic acid filler may have a higher tardive adverse event rate when triggered.

Background: Although the published literature has grown exponentially during the last few decades, managing medication-related osteonecrosis of the jaws (MRONJ) remains challenging. Since the first description of adipose-derived stem cells, cell therapy showed promising perspectives in surgical treatment of MRONJ. In this study, the beneficial effect of fat graft in surgical treatment of stage 2 and 3 MRONJ patients was assessed. Methods: A retrospective analysis of the evolution pattern of the disease was conducted comparing the outcomes of MRONJ patients who underwent sequestrectomy followed by fat graft (n = 9) and those who received sequestrectomy alone (n = 12). Results: Improvement of the disease stage was observed in 77.8% vs. 22.2% cases in group A and B, respectively (p = 0.030); disease stability was documented in 11.1% vs. 25.0% cases in group A and B, respectively (p = 0.603); worsening of MRONJ stage was observed in 11.1% vs. 50.0% cases in group A and B, respectively (p = 0.159). Conclusions: Despite the small sample size, this study suggests that fat graft may represent a promising low-risk and cost-efficient adjunctive therapy in the surgical treatment of MRONJ patients.

Background: The demand for interdisciplinary orthodontic treatment has increased significantly in the past few years, especially in adult patients. This kind of treatment requires careful clinical management, as consequence of the possible complications and limits related to adult age. However, the use of skeletal anchorage and three-dimensional (3D) digital technology has deeply revolutionised diagnostic planning and treatment strategies. Methods: A fully digital approach to the treatment of a Class II patient with a gummy smile and mandibular deficiency and deviation, consisting of initial surgery followed by the use of aligners and skeletal anchorage, is described. Results: The 3D, fully digital pre-evaluation enabled clinicians to accurately and reliably plan the surgical procedure and subsequent orthodontics, including the individualised positioning of stabilisation plates and a splint for maxillary and chin surgical movements. This allowed for the improvement of the patient’s facial aesthetics and dental occlusion without the use of visible orthodontic appliances or the occurrence of pre-surgical aesthetic worsening. Conclusions: This approach could be very effective for adult patients seeking aesthetic treatment options for facial and dental aesthetic improvement.

Lipodystrophy is an alteration of fat metabolism that commonly affects HIV-1 positive patients treated with antiretroviral therapy (ART). The facial area is most commonly affected by peripheral lipoatrophy, thus becoming a social stigma related to chronic HIV. Several treatments have been proposed, such as modification of diet, lifestyle and both surgical and nonsurgical procedures. The goal of our systematic review is to examine published clinical studies involving the use of polyacrylamide filler for the treatment of HIV FLA, and to provide evidence-based recommendations based on published efficacy and safety data. Our research was performed on published literature until April 2021. Polyacrylamide gel is a volumetric gel that has been proven stable, nontoxic, nonallergenic, nonembryotoxic and nonabsorbable. Poly-l-lactic acid (PLA) is a biocompatible, biodegradable, synthetic polymer derived from lactic acid. We believe it is essential to draft a pre- and post-injection and operative protocol to define an even setting for the clinical condition. It is desirable that such specifications are included in a large randomized controlled trial and the follow up is longer than the studies that we found, because as we have seen in the literature there are reported adverse events even 3 or 5 years after the injections.

The aim of this study is to analyze surgical and functional outcomes in order to verify the applicability of surgical treatment guidelines as foreseen by MASCC/ISOO/ASCO 2019. Patients affected by stage 2 MRONJ refractory to conservative management were grouped if underwent surgical resection (Group A) or debridement (Group B). Health-related quality of life was evaluated by using the European Organization for Research and Treatment of Cancer questionnaires, QLQ-C30 and H&N35. Statistical analysis was performed using Wilcoxon/Mann–Whitney test, Kaplan–Meier test, Cox regression model and Cox multivariate regression. Group A showed higher complete healing cases vs. group B. Recurrence rate difference in group A vs. group B was statistically significant. Debridement is an unfavorable prognostic factor when compared to surgical resection (p = 0.0032, HR 4.9). Quality of life mean values showed a marked improvement in Group A and a slight improvement in Group B. Debridement has 4.9 times more risk to develop recurrence when compared to surgical resection. A more satisfactory quality of life was shown in patients subject to resective surgery with an improving trend from baseline. Debridement patients showed more variability of results and an overall negative trend at the end of the 6-month follow-up.

The use of hyaluronic acid (HA) injectable fillers has become increasingly widespread in facial recontouring and rejuvenation. We report our experiences to emphasize the role of HA fillers as tools beyond aesthetic treatments in cases of post-surgical facial sequelae. HA fillers are generally used for aesthetic rejuvenation, but one potential new horizon could be their application in trauma, reconstructive, and craniofacial surgery. This study was conducted retrospectively, evaluating medical reports of patients treated at the Maxillofacial Surgery Unit, University of Campania “Luigi Vanvitelli”, Naples, for lip incompetence, trauma, oncological, reconstructive, and craniosynostosis surgery sequelae. Visual analog scale (VAS) evaluation was performed to assess patient satisfaction. No major complications (i.e., impending necrosis or visual loss) were reported. Bruising and swelling was reported for 48 h after lip injection. At the immediate VAS evaluation, 67% of the patients were “extremely satisfied” and 33% “satisfied”. In those 33%, VAS scores changed to “extremely satisfied” at 6–9 weeks and 3–6 months of VAS evaluation (contextually to improvement in tissue flexibility, elasticity, and aesthetic appearance). Results indicate that this minimally invasive approach achieves a high level of aesthetic enhancement, improving patient satisfaction. The concept of HA filler applications could be a frontier that may be applicable to other areas of reconstructive facial plastic surgery.

Abstract Background A three-dimensionally favourable mandibular bone crest is desirable to be able to successfully implant placement to meet the aesthetic and functional criteria in the implant-prosthetic rehabilitation. Several surgical procedures have been advocated for bone augmentation of the atrophic mandible, and the sandwich osteotomy is one of these techniques. The aim of the present case report was to assess the suitability of segmental mandibular sandwich osteotomy combined with a tunnel technique of soft tissue. Based on our knowledge, nobody described before the sandwich osteotomy with tunnel technique to improve the healing of the wound and meet the dimensional requirements of preimplant bone augmentation in cases of a severely atrophic mandible. Case presentation A 59-year-old woman with a severely atrophied right mandible was treated with the sandwich osteotomy technique filled with autologous bone graft harvested by a cortical bone collector from the ramus. Clinical examination revealed that the mandible was edentulous bilaterally from the first molar to the second molar region. Radiographically, atrophy of the mandibular alveolar ridge in the same teeth site was observed. We began to treat the right side. A horizontal osteotomy of the edentulous mandibular bone was then made with a piezoelectric device after tunnel technique of the soft tissue. The segmental mandibular sandwich osteotomy (SMSO) was finished by two (mesial and distal) slightly divergent vertical osteotomies. The entire bone fragment was displaced cranially, and the desirable position was obtained. The gap was filled completely with autologous bone chips harvested from the mandibular ramus through a cortical bone collector. No barrier membranes were used to protect the grafts. The vertical incisions were closing with interruptive suturing of the flaps with a resorbable material. In this way, the suture will not fall on the osteotomy line of the jaw; the result will be a better predictability of soft and hard tissue healing. Conclusions Segmental mandibular sandwich osteotomy is an easy and safety technique that could be performed in an atrophic posterior mandible. Future studies involving long-term follow-up are needed to evaluate the permanence of these results.

Background. In this article, we describe a nonsurgical approach based on hyaluronic acid filler injection to restore the facial features of a delayed diagnosis of malar fracture. We analyze the differences between surgical and nonsurgical solution: in case of early detection, the surgical approach is the gold standard of treatment. However, in cases of delayed facial fracture diagnosis without functional impairment, nonsurgical procedures could be considered an alternative tool as we show in the present case report. Aims. The aim of this study is to underline the importance of a complete aesthetic restoration in patients treated for noncosmetic purposes. Patients/Methods. We present a case of a 26-year-old male patient with a delayed diagnosis of malar fracture without functional impairment that was treated with hyaluronic acid (HA) filler injections. Results. The patient was followed up for 1 year showing stable results for the first 8 months; at the 12-month follow-up, a touch-up was suggested due to partial resorption of the filler. Conclusion. This is the first case describing a facial fracture treated with HA injections for only recontouring purposes. We assess that nonsurgical cosmetic procedures could be considered a “new” tool in the process of facial rehabilitation but only when functional problems are not associated with facial trauma.

Since the advent of HIV antiretroviral therapies at the end of the 20th century, the morbidity and mortality rates associated with HIV infection have decreased dramatically. Unfortunately, these benefits are associated with substantial morphologic changes in the body, such as abnormal fat distribution with peripheral lipohypertrophy and facial lipoatrophy. Facial wasting is considered the major stigma for HIV–infected people and may result in reduced antiretroviral adherence. Patients suffering from the stigmata of HIV infection can benefit from non-surgical aesthetic treatments performed with fillers or lipolytic agents that provide a quick and reliable service for facial rejuvenation, with high patient satisfaction and a low risk of complications. In the present paper, a retrospective analysis of complications following non-surgical aesthetic treatments (calcium hydroxyapatite-based filler, hyaluronic acid filler, polyacrylamide hydrogel filler and dehoxycholic acid injections), in a cohort of 116 consecutive HIV+ patients, treated over a period of 12 years, was performed. With the exception of the tardive swelling reported after calcium hydroxyapatite injections, complications were recorded just after polyacrylamide hydrogel treatment as small, palpable, nonvisible nodules or aseptic abscess. Our experience is consistent with those already published in the literature and the complication rate seems to be comparable to non-infected patients.

The aim of this retrospective case series was to discuss indications, surgical outcomes, and donor site morbidity in the use of superficial temporal artery perforator (STAP) flaps in intra-oral or extra-oral facial reconstruction. This study involved 9 patients treated with a STAP flap at the Maxillo-Facial Surgery Unit of the University of Campania “Luigi Vanvitelli”, Naples. A STAP flap was used alone or in combination with other local flaps, for the coverage of facial soft tissue defects, after the resection of craniofacial malignant tumors (n = 7) or as a salvage flap, in partial or total microvascular flap loss (n = 2). The STAP flap was proven to be a valuable surgical option despite it not being frequently used in facial soft tissue reconstruction nor was it chosen as the first surgical option in patients under 70 year’s old. Donor site morbidity is one of the major reasons why this flap is uncommon. Appropriate patient selection, surgical plan, and post-surgical touch-ups should be performed in order to reduce donor site scar morbidity.

In this paper, we present a simple way to place the implant into a harvested pocket and to subsequently fix it percutaneously. Eighteen patients (1 male, 13 females, 4 transgender), underwent facial implant placement; a total of 31 implants were placed (1 pair of angles of the mandible implants, 12 pairs of malar/sub-malar implants, and 5 chin implants). The intraoral approach was performed on 15 patients, and on the remaining three patients, the sub-ciliary lower lid approach was preferred. Patients were followed up for at least one year with a maximum follow-up of seven years (mean 1.8 years). In all the cases, except one, patients healed without complications. One case of implant displacement and infection was recorded. No other complication was documented. The technique described is similar to the one suggested by Peled, although some useful tips were added, namely the use of sutures, not only to fix the implant but also to drive it into the harvested pocket. In addition, larger absorbable “left in place” sutures were used, avoiding accidental implant dislocation during their removal. Further studies are required to gain a more complete understanding of the effectiveness and reproducibility of this surgical technique.

The aim of this case report was to evaluate the use of Partsch I cystotomy in order to preserve a dental implant located in an odontogenic cyst extended from 3.2 to 4.4. A 50 year-old woman showed a circular, well-defined unilocular radiolucent area, Ø2.5 cm, in the right mandibular region with an oral implant intruding inside it. The overdenture in the mandibular right site showed no clinical mobility. The authors decided to perform a surgical treatment aimed to preserve the implant. The patient underwent Partsch I surgery followed by iodoform gauze insertion replaced weekly for one month, revision of the previous orthograde endodontic treatments, and an acrylic resin obturator prosthesis application for the following two months. The twelve month follow-up showed no clinical mobility of the right lateral mandibular implant prostheses. Radiographical analysis revealed cystic lesion healing and perimplant bone regeneration. This report highlights the opportunity to apply cystotomy when the cyst involves a dental implant and undermines its stability. This possibility is offered by the peculiar clinical scenario where the implant was stabilized by the presence of a previous prosthetic fixation. Our study led to the application of an operative protocol that allowed for the preservation of the implant.

Arthrocentesis in temporomandibular joint disorders can be associated with the intra-articular infiltration of various drugs with the objective of increase treatment efficacy. The aim of this study was to evaluate the clinical indexes variation in patients affected by temporomandibular joint disorders treated with arthrocentesis and sodium hyaluronate (SH) injections. A total of 28 patients suffering from temporomandibular joint disorders underwent one cycle of five arthrocentesis and infiltrations of sodium hyaluronate. Spontaneous mouth opening improved from 36.3 ± 7.5 mm to 45.1 ± 1.9 mm at six months follow-up. A significant reduction in the pain at rest and during mastication mean values emerged at follow-up (P < 0.0001). The mean masticatory efficiency, evaluated through a visual analogic scale, showed improvement at the follow-up period, highlighted by the increase of mean value from a baseline of 3.1 ± 1.2 to a mean value of 8.5 ± 1.2 (P < 0.0001). The mean severity of the joint damage at baseline time was 2.4 ± 0.9 and decreased to 0.4 ± 0.3 at the end of the follow-up period. The decrease in values is confirmed by statistical test (P < 0.05). Our data show how arthrocentesis integrated with sodium hyaluronate infiltrations performed under local anesthesia is a valid method of treating temporomandibular joint disorders.