Enforcing Dirichlet boundary conditions in physics-informed neural networks and variational physics-informed neural networks.

In this paper, we present and compare four methods to enforce Dirichlet boundary conditions in Physics-Informed Neural Networks (PINNs) and Variational Physics-Informed Neural Networks (VPINNs). Such conditions are usually imposed by adding penalization terms in the loss function and properly choosing the corresponding scaling coefficients; however, in practice, this requires an expensive tuning phase. We show through several numerical tests that modifying the output of the neural network to exactly match the prescribed values leads to more efficient and accurate solvers. The best results are achieved by exactly enforcing the Dirichlet boundary conditions by means of an approximate distance function. We also show that variationally imposing the Dirichlet boundary conditions via Nitsche's method leads to suboptimal solvers.

Parameters and outcomes in 525 patients operated on for oral squamous cell carcinoma.

PURPOSE: This report analyzed the outcomes of patients undergoing surgery for oral squamous cell carcinoma (OSCC) to identify the value of prognostic factors. MATERIAL AND METHODS: A total of 525 patients were studied who had undergone surgery for oral squamous cell carcinoma (OSCC) between 2000 and 2011, of whom 222 had received postoperative radiation-therapy (PORT) and or chemoradiation-therapy (PORTC). For each patient, personal data, histological findings, treatment and outcome were recorded and analyzed statistically. Survival curves were calculated using the Kaplan-Meier algorithm, and the difference in survival among subgroups was examined. RESULTS: The overall survival (OS) and disease-specific survival (DSS) 5-year survival rate in the 525 patients were respectively 71.38% and 73.18%. The differences in the overall survival and disease-specific 5-year survival were significant (p < 0.05) for age < 40 years, site of origin, N status, staging, grading, osseous medullar infiltration, and perineural invasion. In patients undergoing radiation therapy, only perineural invasion negatively influenced the survival prognosis. In 150 pT1 cases of tongue and floor-of-mouth cancer, an infiltration depth (ID) > 4 mm was statistically correlated with poorer prognosis. CONCLUSIONS: The results demonstrate an improvement in the 5-year OS and DSS rates during the past decade compared with the previous decade. Univariate analysis revealed that age, tumor staging, and lymph node involvement, extracapsular spread, grading, perineurial invasion, infiltration depth, and osseus medullary invasion were associated significantly with overall survival and disease-specific survival.

Correction of a mandibular asymmetry after fibula reconstruction using a custom-made polyetheretherketone (PEEK) onlay after implant supported occlusal rehabilitation.

This study describes an unusual case of mandibular asymmetry after fibula free flap reconstruction in a young man following major facial trauma that was corrected using a custom-made polyetheretherketone prosthesis. There is little information in the literature on the use of alloplasts to correct mandibular asymmetry as interest in 'aesthetic re-modelling' has traditionally focused on nasal, zygomatic and chin regions. This report demonstrates that this technique can be used successfully to address selected cases of mandibular asymmetry.

Correlation between Skp2 expression and nodal metastasis in stage I and II oral squamous cell carcinomas.

PURPOSE: The aim of this study was to investigate the role of S-phase kinase associated protein (Skp2) in the development of nodal metastasis and to assess its influence on prognosis in stage I and II oral squamous cell carcinomas (OSCCs). EXPERIMENTAL DESIGN: Seventy-one patients affected by OSCC (stage I-II) were observed in the period ranging from March 2003 to December 2006. The research was performed using immunohistochemical and histopathological analysis. RESULTS: The overall survival rate was 89.6% at 3 years, 87% at 5 years and 80.7% at 10 years. Patients with vascular or perineural invasion showed no statistically significant survival difference when compared with the ones with no invasion. The tumour depth of invasion did not prove to be related to the metastatic potential. Nine of the seventeen patients with Skp2 positive nuclei (≥20%) developed nodal metastasis. Conversely, only 6 of the 54 patients with a nuclear positivity lower than 20% developed a laterocervical metastasis (P=0.001). When comparing survival curves of Skp≥20% and Skp2<20% OSCCs, no significant P value emerged from the statistical analysis. CONCLUSIONS: This study is the first to report an important correlation between an Skp2 expression lower than 20% and the capability of the tumour not to develop nodal laterocervical metastases (P=0.001).

Induction chemotherapy followed by concurrent chemoradiotherapy in advanced head and neck squamous cell carcinoma.

BACKGROUND: A phase II study was carried out to investigate an induction regimen with cisplatin, paclitaxel followed by radiotherapy concurrent with weekly cisplatin for locally advanced squamous cell carcinoma of the head and neck. PATIENTS AND METHODS: Stage III-IV disease patients were eligible. Two cisplatin (100 mg/m2) and paclitaxel (175 mg/m2) courses were administered every 21 days followed by standard fractionated external beam radiotherapy (approximately 70 Gy), concomitant to weekly cisplatin (30 mg/m2). RESULTS: Thirty-five patients were enrolled: over 70% had unresectable disease with bulky lesions. Grade 3-4 neutropenia developed in 14% and G3 mucositis in 23%. Locoregional control was achieved in 51%. Median time to progression and overall survival were 10,7 and 17 months respectively; 2- and 3-year survival rates were 30% and 25% respectively. CONCLUSION: Our induction two-drug regimen followed by chemoradiotherapy with concurrent weekly cisplatin was well tolerated with low acute toxicity and good locoregional control and survival rate.

Total temporomandibular joint prosthesis as a surgical option for severe mouth opening restriction. A case report of a bilateral intervention.

Several conservative treatment approaches to the disorders of the temporomandibular joint (TMJ) have been described in the literature. Nonetheless, in a minority of cases not respondent to reversible conservative therapies a surgical approach to the TMJ is needed. In recent years, a total temporomandibular joint replacement with alloplastic prosthesis have been introduced as a treatment option in the presence of a severely damaged or mutilated joint, mainly resulting from severe joint diseases, as in the case of complex inflammatory-degenerative diseases, or failure of previous surgeries. The present paper described a case report of a bilateral temporomandibular joint replacement intervention in a female patient with severe mouth opening restriction and pain in the TMJ area. Also, a discussion of the potential indications for TMJ replacement has been provided, along with the description of the surgical procedure.

Transverse maxillary distraction with a bone-anchored appliance: dento-periodontal effects and clinical and radiological results.

In 29 adult patients presenting with maxillary deficiency, a bone-anchored palatal distractor (Surgi-Tec NV, Brugge, Belgium) was applied after osteotomy of the anterolateral walls of the maxillary sinuses, midpalatal suture, and, eventually, separation of the pterygomaxillary sutures. Expansion proceeded at a rate of 0.33-0.66 mm per day and the device was retained for 4-6 months for consolidation. Active orthodontic therapy was started after 8-10 weeks. The increment of arch width and the perimeter were evaluated using dental casts. Tooth thermal sensitivity and the periodontal side effects of treatment were monitored clinically after distraction, at device removal, and after 1 year. Bone healing was also investigated during the procedure using conventional radiological techniques. This experience confirms that transverse maxillary distraction is an effective technique in adult patients, leading to the formation of new bone. There were no noticeable intraoperative complications, but postsurgical periodontal side effects were documented. The procedure offers advantages over traditional teeth-borne appliances in terms of rapidity of treatment and the absence of mechanical forces acting on the teeth. Further evaluation is required to assess the long-term stability and periodontal consequences of this technique.

[Facial anthropometry and aesthetic perception in young italian subjects: their use for orthognatic surgery]. / Antropometria e percezione estetica del volto in un campione di popolazione italiana. Considerazioni ai fini della chirurgia ortognatica.

BACKGROUND: Aesthetic requests of patients undergoing orthognatic surgery have increased over time and represent nowadays the leading subjective motivation for the patient and a major aim of the treatment for the surgeon. In this regard, anthropometric evaluation has considerably improved the diagnostic capacity of the orthodontist and of the surgeon. Aim of the study is to provide the orthognatic surgeon with anthropometric normal values based on a sample of aesthetically pleasant Italian subjects and to discuss the use of a simplified aesthetical analysis in the set-up of the surgical plan and in the evaluation of treatment outcome. METHODS: The present study analyses 94 Italian subjects, by means of anthropometric measurements on photographic images, considering 28 facial proportions and 33 angular values. These figures were compared with the aesthetic judgement provided by 3 common observers and 3 orthodontists. The aesthetic score was attributed on a subjective discrete scale (common observer: above average/average/below average; orthodontist: eumorphic/ dismorphic). Data were also compared with similar evaluations on North-American and African subjects reported in the international literature. RESULTS: This study confirms the sexual dismorphism and the ethnic variability already reported by other Authors and documents specific morphological characters in the Italian population. CONCLUSIONS: The described method appears acceptably simple and consistent for clinical application. Its use in orthognatic surgery may provide objective and reproducible data for evaluating the aesthetic outcome of treatment.

MET receptor is overexpressed but not mutated in oral squamous cell carcinomas.

Oral squamous cell carcinoma (SCC) is a neoplasm characterized by a high degree of local invasion and an elevated rate of metastasis to cervical lymph nodes. It has been shown that the Hepatocyte Growth Factor/Scatter Factor Receptor Met is constitutively activated in many human tumors of epithelial origin and that it plays a critical role to confer invasive properties to neoplastic cells. Most frequently, Met activation is due to receptor overexpression, but also point mutations in the tyrosine kinase domain can lead to deregulated activation. Here we show that in all the primary tumors examined this receptor is overexpressed. Direct sequencing of Met mRNAs failed to find any activating mutation in its intracellular domain. Moreover, in cell lines derived from squamous cell carcinomas, HGF-induced activation of Met resulted in the acquisition of invasive properties. All together these data suggest that the MET oncogene is involved in progression of squamous cell carcinoma toward an invasive-metastatic behavior.

[Incidence of psychopathologic symptoms in patients treated for mouth cancer]. / Valutazione dell'incidenza dei sintomi psicopatologici in pazienti trattati per carcinoma del cavo orale.

BACKGROUND: The first aim of the study is to evaluate the possible onset of anxiety, major or minor forms of depression and delirium in patients treated for head and neck malignancies. The second aim is to study the possible association between the psychological conditions and the different parameters connected with the treatment (site of tumor, time of hospitalisation and surgery, kind of reconstruction). METHODS: The study included 35 patients (21 males; 14 females) with diagnosis of head and neck squamous cell carcinoma (HNSCC). All the patients were examined before surgery, during the preoperative phase, and after surgery. Three evaluation questionnaires were used during the interview: Spielberg's StaiY1 and Y2 test, to evaluate anxiety, and Zung Self-Rating Depression scale, to evaluate depression. RESULTS: Patients revealed anxiety before surgery, while after intervention the level was normal. There was a prevalence of anxiety over depression. There was no correlation between diagnosis, site of tumor, time of hospitalisation and psychological symptoms. An association between time of surgery, kind of reconstruction, anxiety and depression was found. The patients with a higher degree of anxiety were more tending to delirium. CONCLUSIONS: Malignancy of the head and neck causes considerable physical and psychological problems which may adversely affect the quality of life during and after treatment. The better reconstruction is correlated with the lower psychopathological problems. The study underlines the need to offer psychological support during diagnostic and therapeutic procedures.

Dimensions and volumes of the orbit and orbital fat in posttraumatic enophthalmos.

OBJECTIVES: To estimate from 2D and 3D-CT the anatomical defects that are most likely to be responsible for posttraumatic enophthalmos. MATERIALS AND METHODS: The morphology and dimensions of the orbit and of fat content were investigated in 25 patients 6-12 months after treatment for complex orbital fractures by image analysis and volumetric estimation from 2D and 3D-CT. RESULTS: The shape of orbit was very often changed from conical to more rounded due to enlargement of the posterior segment. The retrobulbar fat appeared fragmented and dislocated posteriorly. No changes were observed in the structural appearance or radiodensity of either the orbital fat or muscles. There was reduced sagittal eye projection, increased width of the orbital rim, downward dislocation of the posteromedial orbital floor, and increased volume in the posttraumatic orbits which was significantly different (P < 0.05). Enophthalmos was correlated with orbital volume and height of the retrobulbar portion of the orbit. The volume of fat did not correlate with enophthalmos. CONCLUSIONS: Posttraumatic enophthalmos appears to be more commonly related to failure in correcting the orbital volume and in reducing the outward dislocation of the posterior orbital floor and not to changes in the fat content.

[Odontogenic kertocysts. Review of a series of cases and long-term clinical control]. / Le cheratocisti odontogene. Revisione di una casistica e controllo clinico a distanza.

BACKGROUND AND AIMS: The aim of this retrospective study was to identify and evaluate the clinical characteristics and incidence of recidivation in a series of 40 cases of keratocyst consisting of 31 primary lesions, 7 cases of primary recidivation (17.5%) and 2 cases of secondary recidivation (5%). All the lesions were large sized and were treated using surgery. All patients underwent an annual clinical control for a minimum follow-up of seven years. METHODS: The authors present a series of 40 odontogenic keratocysts treated between 1985 and 1996 by the Division of Maxillofacial Surgery at Turin University. The series consisted of 40 keratocysts including 31 primary lesions, 7 cases of primary recidivation (17.5%) and 2 cases of secondary recidivation (5%); 12 patients were female (38.7%) and 19 were male (61.3%). The mean age of patients was 42 years old. The clinical records and enclosed X-ray documentation (OPT X-ray, head X-ray, face X-ray) were examined for each patient, together with histological findings. Each case then underwent an annual follow-up. RESULTS: The review of clinical data and the examination of X-ray documentation showed that 28 lesions developed in the mandible and only 3 cases in the upper jaw. From a therapeutic point of view, keratocysts localised in a mandibular site were managed using cystectomy in 19 cases and in 18 cases this was followed by marsupialisation. Caldwell-Luc's operation was used in 2 cases of intrasinusal maxillary development, whereas the single case of extrasinusal development underwent cystectomy. Recidivation always involved the mandible and occurred in 22% of cases within 5 years of surgery. Of the 19 cases undergoing simple cystectomy, 8 cases (42%) revealed recidivation. Only one (5.5%) of 18 cases treated using cystectomy and marsupialisation showed recurrence. CONCLUSIONS: On the basis of their experience and in view of the specific characteristics of keratocysts, in particular the tendency to undergo recidivation, the authors affirm that annual clinical and radiological controls are indispensable and important, including biopsy where necessary, in order to diagnose new lesions promptly irrespective of the surgical technique used.

Maxillofacial trauma in the elderly.

PURPOSE: This article gives a general description of the incidence, causes, and complexity of maxillofacial fractures in the elderly and discusses whether modification is required in assessment, surgical indications, and techniques in such cases. PATIENTS AND METHODS: A retrospective clinical and radiologic study evaluated 222 patients older than 60 years of age (mean age, 70.3) hospitalized with maxillofacial trauma over the period 1987 to 1996 in the Division of Maxillofacial Surgery, University of Turin. The patients were classified according to the following parameters: age, cause of injury, site of trauma, presence of associated fractures, pertinent medical history, type of treatment, length of hospitalization, and complications. The data were compared with those from a control group consisting of 178 adult patients younger than 60 years of age. RESULTS: The presence of a preexisting systemic pathologic condition was the most important factor in determining hospitalization time, which was greater than in the control group. In 89 patients (40.1%), no treatment was considered necessary, whereas 133 patients (59.9%) were treated by surgery. In 115 patients (86.5%), the fractures were treated by open reduction and internal fixation, whereas closed reduction was used in 18 patients (13.5%). There were complications with six patients (2.7%), and one died in the hospital. CONCLUSIONS: The findings of this study suggest that surgical intervention is less frequently indicated in facial trauma of the elderly because of physiologic, psychologic, and social changes brought on by the aging process. The principles of treatment, the results, and the complications do not differ greatly in this group when compared with the normal adult population.

Hyperplasia of the mandibular coronoid process: long-term follow-up after coronoidotomy.

The aim of this study was to evaluate long-term results of treatment by intraoral coronoidotomy and prolonged physiotherapy in five patients with mandibular coronoid process hyperplasia. Five consecutive cases of coronoid process hyperplasia were studied (two unilateral and three bilateral) at the Department of Maxillo-facial Surgery of the University of Turin during the period 1985-1990. All patients were treated by intraoral coronoidotomy and given physiotherapy from the third postoperative day. This continued for an entire year. A clinical and radiological follow-up (average 39.4 months), in three cases over a 5-year period, was completed. Three months after the operation, all patients had achieved satisfactory improvement in mandibular interincisal opening. The mean value for mouth opening at the end of follow-up was 42 mm. Radiographic follow-up showed the presence of a coronoid process almost the size of the original, apparently united with the mandibular ascending ramus, with moderate dislocation and inclination posterior to the body of the zygomatic bone. The results of this study indicate that treatment of coronoid process hyperplasia by intraoral coronoidotomy, when combined with prolonged postoperative physiotherapy, gives satisfactory and stable long-term results in the correction of coronoid-malar interference.

[Removable prostheses with controlled distribution of forces on endosseous implants]. / Protesi rimovibile a distribuzione controllata delle forze su impianti osteointegrati.

The differentiated behaviour of dental abutments and alveolar mucosal tissues following functional loading has always created design problems in the field of removable partial prostheses. This situation of disequilibrium is particularly clear when natural piers are replaced by osteointegrated implants which are by definition unable to adapt to the masticatory load. In order to avoid this different behaviour, the authors feel it is advisable to use a removable partial prosthesis fitted with telescopic retention, defined as "controlled distribution of the forces", which can transfer the functional masticatory load to the osteointegrated implants and alveolar mucosal structures in a harmonious, balanced and homogeneous manner. The authors give a detailed description of the structure and working of this particular type of prosthesis, highlighting its advantages, namely: 1) controlled distribution of occlusal forces to osteointegrated implants and alveolar osteomucosal structures; 2) reduced number of implants required (2 are sufficient); 3) stability of prosthesis comparable to a fixed structure; 4) possibility of removing the latter with the advantage of maintaining oral hygiene around implants; 5) reduced size of prosthesis. Given that this type of prosthesis has been designed, realized and fitted to natural piers, with optimal clinical results, by the Dental Implant Department of the Dentistry Clinic of Turin University since 1969, the authors affirm that this prosthetic structure is particularly suitable in cases of edentulism with advanced maxillary atrophy.

[The validation of stereolithographic anatomical replicas: the authors' own experience and a review of the literature]. / Convalida delle repliche anatomiche stereolitografiche: esperienza personale e revisione della letteratura.

The visual three-dimensional (3D) reconstruction of CT findings has been used since the Seventies to design and plan complex surgical procedures. The availability of such models and the development of computer science have permitted, since the mid-Eighties, the medical use of rapid prototyping for anatomical modelling. We studied the technical steps of CT data processing for rapid prototyping and the dimensional and structural accuracy of replicas of skeletal components relative to the originals. A dried mandible and an arthrotic hip joint were compared with their stereolithographic replicas using the measurements made on CT images. The 3D graphic models were processed with a commercially available software and replicated with an SLA 250 stereolithographer (3D System Inc, Valencia CA, USA). Satisfactory morphologic agreement was found between the original and its replica. The mandibular replica exhibited dimensional errors ranging 0 to 4.03%, z-axis shortening and an increase in gonial angle, but with a reliable reproduction of details. The hip replica exhibited dimensional errors ranging .2% to 8.53%; it appeared to be less affected than the mandibular replica by geometrical distortion but it was less accurate in the reproduction of cancellous bone and arthrosis. The accuracy of the solid replicas depends, in the different manufacturing steps, on several factors, namely: during data acquisition, the accuracy and suitability of original data, depending in turn on equipment and examination parameters--especially the algorithm, acquisition time, gantry tilt and slice thickness; image thresholding and manipulation procedures during graphic model creation; data transfer, creation of the necessary supports and replica finishing during manufacturing; residual polymerization affected by environmental agents and preservation conditions during maintenance.

[Brown tumor of the jaws]. / Tumore bruno dei mascellari.

Brown tumour is one of the forms in which fibrous-cystic osteitis, which represents the terminal stage of the bone remodelling processes during primary or secondary hyperparathyroidism, is manifested. For years brown tumour was regarded as a typical lesion of primary hyperparathyroidism, but cases of brown tumours in patients with hyperparathyroidism secondary to renal failure were increasingly often reported in the literature. From an epidemiological point of view, the frequency of brown tumours in patients with renal insufficiency is extremely variable, as is the bone site affected. Several bone segments can be affected at once, but the ethmoid and frontal sinus are rarely reported. Symptoms are caused by the considerable dimensions of the brown tumour and its localisation: in the jawbones it may present sometimes painful, hard and clearly palpable swellings; if large, the tumour may deform the appearance of the bone segments affected or alter the function of the masticatory apparatus. In other cases, there is a complete absence of clinical symptoms and diagnosis may be totally coincidental during the radiological examinations. In histological terms, brown tumours are made up by a cell population consisting of rounded or spindle-like mononucleate elements, mixed with a certain number of plurinucleate giant cells, resembling osteoclastic cells, among which recent haemorrhagic infiltrates and hemosiderin deposits (hence the brown colour) are often found. The aim of this study was to report three cases from a population of 107 patients undergoing haemodialysis at the Turin University Centre. In conclusion, the localisation of maxillary brown tumours appears to prefer a young, female population; brown tumours are rarely an early sign of hyperparathyroidism in haemodialysis patients, but they often appear in conditions of advanced hyperparathyroidism which have escaped medical control either owing to unsuitable therapy or scant patient compliance; they are rapidly evolving lesions whose regression may be very slow or not occur even after total parathyroidectomy; the severity of the lesion caused by a brown tumour may lead to evident osteolysis in the maxillofacial district, thus suggesting the need for early and regular radiological screening; in the event of lesions which are already present, from the authors' point of view, the choice of treatment must be oriented towards parathyroidectomy.

[Adenophlegmons of the neck area. A case report and review of the literature]. / Adenoflemmoni della regione cervicale. Presentazione di un caso e revisione della letteratura.

Adenopathies in general and cervicofacial adenopathies in particular are a pathology that can affect both medical and surgical disciplines. They may be found in both acute and chronic disorders, in children and in adults, and in local or systemic forms with benign or malignant pathogenesis. It is clear that the differential diagnosis and consequently the therapeutic approach may be complicated at times by the variety of pathological processes. Interest in the case reported her is, in our opinion, justified by the rare finding in the age of antibiotics of such striking symptoms. The severity of local symptoms and the general conditions of the patient resulted in the need for surgery under anesthesia in order to enable the extensive collection of purulent matter to be drained. The postoperative course showed a marked and progressive improvement of the patient's general and local conditions, even a few hours after surgery. Given that several factors contribute to determining the evolution of septic conditions (patient's general and in particular immunological status) and given that, owing to the aspecific nature of symptoms, the diagnosis and relative specific therapy may be delayed, it can be seen that the clinical picture may evolve and be complicated by massive general manifestations, sufficient in extreme cases to endanger the patient's life, in the form of acute and sudden respiratory disorders and or more gradually with generalised septic conditions (encephalitis, mediastinitis and generalised sepsis). The objective to be attained is therefore a careful diagnosis and the immediate implementation of medical procedures in order to remove the cause that has triggered off the pathology.

[Fine needle biopsy in the preoperative diagnosis of parotid tumors]. / Validità dell'agobiopsia ad ago fine nella diagnostica preoperatoria delle tumefazioni parotidee.

Fine-needle aspiration biopsy is of particular interest in the parotid sites because, here, pathology with different treatments and prognosis manifest themself in the same way. The preoperative diagnosis of neoplasm is often problematic. As is known, this is correlated to several factors including histology, clinical and instrumental semiology. The instrumental image techniques (sialography, thermography, scintigraphy, ultrasound diagnosis, tac sialo-tac) give information as to size and location of the mass in question. Only rarely does it give any indication of whether the mass is malignant or benign. The authors systematically studied 386 parotid tumors. The method utilises a traditional technique (needle n. 12/2 gauge 1/4) and microscope examination with immediate dyeing to verify the correctness of the sample. 352 cases underwent surgery with subsequent histological verification. The results demonstrated a generical concordance of cytology and histology in the diagnosis of malignancy equal to 95%. The concordance of exact histology was 91%. The discordance regards, above all, the malignant neoplasm and particularly the mucoepidermoide and the adenoid cystic carcinoma. Fine needle aspiration demonstrates absolute specificity in the differential diagnosis between parotid and extraparotid pathology.

[Dermoid cysts of the oral floor. A clinical case report and review of the literature]. / Cisti dermoidi del pavimento orale. Presentazione di una casistica clinica e revisione della letteratura.

The authors report two cases of dermoid cysts of the oral floor. The incidence of this pathology in this region is difficult to assess due to the rarity of reported cases. In particular, dermoid cysts appear to derive from the inclusion of epithelial cells on the median line in the fusion point between the first and second branchial arch. Other pathogenetic causes are however reported in the literature, namely traumatic epidermal implants during fetal development in utero. Dermoid cysts are most frequently manifested between the second and sixth decade of life, although cases of younger and older patients have been reported. All the authors agree that there is no sex-related preference. In general, the patient becomes aware of the pathology due to the gradual deterioration of locoregional functional signals: difficulties related to speech, chewing and swallowing. These symptoms are closely correlated to the size of the lesion. The development of the cyst is usually slow and does not involve painful symptoms, but it may become rapid and painful in the presence of concomitant phlogistic processes. In the first case an 18-year-old patient reported the appearance some 4 years earlier of a swelling measuring approximately 4 x 2 cm, involving the entire front portion of the oral floor; the swelling was spontaneously painful. Having been referred to the authors'attention the patient showed a swelling which was localized on the mid oral floor, the size of a tangerine and with a hard elastic consistency and taut, shiny mucous covering; the swelling was apparently normotrophic.(ABSTRACT TRUNCATED AT 250 WORDS)