Location of implants in the interforaminal region of the mandible and the consequences for the design of the superstructure

The location and the number of implants to support an overdenture is of major importance for the superstructure design. Sometimes, jaw bone anatomy or posteriorly placed implants enforce the use of an angular bar to achieve a position above the alveolar ridge. Loads on such a bar may introduce a moment on the implants which can result in high bone stresses and eventually the loss of the implants.
This study on stress distribution in the bone around the implants in an edentulous mandible was performed using a three-dimensional finite element model. One model with two implants placed just anteriorly of the mental foramen and connected with an anteriorly placed bar, following the curvature of the alveolar ridge, was compared with two other designs. First with a similar model but now without a bar and secondly with a model with four implants connected with straight bars.
It is concluded that loading a bar, which is placed anteriorly of the interconnecting line between two implants, causes extremely large compressive and tensile stress concentrations in the bone around the implants. Therefore, in those cases, it is advised not to connect the implants or, in case a bar-clip attachment is preferred, to place additional implants in the frontal region.     

Role of the psychologist in the treatment of bruxism

Although there is a controversy about the importance of psychological factors in the development, enhancement and perpetuation of bruxism and other parafunctional activities, the contribution of a psychologist in the treatment of the individual patient is recommended. This contribution consists of diagnostic examination and treatment, most often a short cognitive behavior modification therapy. Because bruxism is mostly examined and treated in relation to the complaints it might cause, especially CMD-complaints, diagnosis and treatment are mostly directed at both. For the diagnosis a questionnaire is used, including a psychological test, which is followed by one or more interviews. The treatment is directed at learning to recognize bruxism activities, to practice alternative behavior, and to learn to cope better with situations that may lead to an increase of bruxism.     

Clinical-experimental study on the temperature behaviour of the mucosa of mouth related to the season of the year

A long-term investigation of 20 juvenile patients indicated a great seasonal and interdiurnal variation of the gingival temperature, which had a trend to a high interindividual correlation. The absolute individual differences was upto 2 degrees C. The lower jaw had a higher temperature than the upper jaw. The temperature of the right and left sides of the jaw differed from each other. The calculation of a standard temperature is only useful, when it is related to the individual sublingual temperature.     

The elimination of the retractility of the skin portion of the nasal septum]

The authors propose a method which decreases the traumatism of surgery for nasal septum repair and helps attain more stable cosmetic results. An open endonasal incision is made behind the alar cartilage pedicles and continued along the fold between the alar and triangular cartilages to the nostril wing base. Perpendicular to this incision and starting from its end, another incision is made, also through the mucosal and cartilagenous tissue to the site where lateral parts of alar cartilages are changed for median. The mucocartilaginous flap is thus cut from the external upper part of the lateral compartment of the alar cartilage. The same intervention is made from the other side. Then the flaps and wound edges are mobilized, the columella is rendered a proper position, and the detected hidden tissue defect is filled with mucocartilaginous flaps. This method is based on correct understanding of the deformation, detection of the latent defect of tissues, and its repair by means of the adjacent tissues making incisions from the nasal cavity. The modification differs favorably from the prototype method.     

Influence of saggital inclination of the teeth and the orientation of the occlusal plane on mesial drift in the dental arch

As a rule, the occlusal plane in man is not flat but curved in the three dimensions. This curved organization is related to a specific phenomena: the continuity of the dental arch without diastema. The Page's proposal of the tangent law explains the sagittal organization of the mandibular teeth by geometrical analyses. A cephalometric analysis of 485 subjects, in natural dentition, is the basis for the present statistical study of the mandibular teeth sagittal inclination, related to the direction of the tangent. Mandibular incisors follow the tangent law, but the long axis of the posterior mandibular teeth exhibits a postero-anterior and progressive differential angle with the direction of the tangent: 15 degrees, 20 degrees, 25 degrees, 28 degrees. The differential angle with the direction of vertical strength during closure movement generates an horizontal strength component, with a tendency to create a forward tooth movement. This horizontal component of force is tightening the proximal contacts, maintaining the continuity of the dental arch: it also originates the mesial "drift" and mandibular incisor crowding.     

Titanium screw implantation to the articular eminence for the treatment of chronic recurrent dislocation of the temporomandibular joint

In this report, the technical details of a new surgical technique are presented for the treatment of chronic recurrent dislocation of the temporomandibular joint. The procedure is performed under local anesthesia. Two millimeters of skin incision is carried out 2-2.5cm below the articular eminence, and a tunnel is created above the superficial musculoaponeurotic plane toward the eminence. Then via a specially designed trocar, a 20mm titanium screw is implanted into the most prominent part of the eminence perpendicularly. Thereafter, the patient is told to actively open his/her mouth, and the luxation and position of the screw is checked with the C-arm fluoroscopy. Once the correct position is assured, the trocar is removed and the incision is sutured with 6/0 prolene.     

Long-term stability of the leveling of the curve of Spee.

The aim of the study was to investigate whether the orthodontic leveling of the curve of Spee is a treatment procedure with a stable result on a long-term basis. Measurements were made on the plaster casts of 149 orthodontically treated patients (57 males and 92 females). The mean age before treatment was 12.8 years (range, 8-25 years). Study casts were taken before treatment (T1), at the completion of orthodontic therapy (T2), and 6.7 years (mean) posttreatment (T3). Inclusion criteria were no extractions, all Angle classifications except Class III malocclusions, and all permanent teeth fully erupted except second and third molars. The curve of Spee and the irregularity index were measured on standardized digital photographs of the casts. Overjet and overbite were assessed with a ruler. Changes in the curve of Spee were correlated with changes in irregularity index, overjet, and overbite from T1 to T3. The following results were noted: (1) leveling of the curve of Spee is a relatively stable treatment procedure compared with a return of incisor crowding and deepening of the bite; (2) neither the initial depth of the curve of Spee nor the initial irregularity index is an indicator for the amount of relapse; (3) the amount of leveling is not correlated with the relapse of the 4 tested parameters (curve of Spee, irregularity index, overjet, and overbite); and (4) there is a mild correlation between the relapse of the curve of Spee and the relapse of the irregularity index, overjet, and overbite. According to the results of the study, leveling the curve of Spee during orthodontic treatment seems to be very stable on a long-term basis; it was weakly correlated with the other variables tested.     

A method for the contact-free computerized visualization of the movements of the head of the mandible in the temporomandibular joint

A method for recording the functional movements of the head of the temporomandibular joint (TMJ) is proposed. It is based on the use of a special automated image processing system (AIPS) consisting of a TV camera with a feeding block, TV monitor, and a PC. Sixty subjects aged 20-40 years with orthognathic occlusion without maxillodental disease were examined. Contact-free registration included: 1) layout of the skin of the face; 2) videorecording of mandibular movements during special functional tests; and 3) computer processing of results. Contact-free registration of the position of the TMJ head permits objective and highly accurate reproduction of the system of elements of the maxillodental system during prosthesis making and fixation. Comprehensive study of functional movements of the mandible by means of AIPS facilitates orthodontic treatment of patients with abnormal height of the lower part of the face and helps diagnose the joint abnormalities. Contact-free diagnosis decreases and in many cases even rules out unjustified radiation loading of patients in examinations of the maxillodental system.     

International collaboration and research in the organization of the education of dentists and the public.

The dental curriculum in Western countries is still heavily biased towards technical competence in restorative procedures. Despite the evidence from many countries that curative dentistry has failed to make a significant impact on dental health, there is a reluctance to change to a preventive emphasis. Unfortunately dental education in developing countries is being modelled on the same pattern even though this is totally irrelevant to local needs and resources. The greatest need is for health education designed to influence the lifestyle of people in a way which will reduce the prevalence of dental disease. Unfortunately the dentist's present training does not fit him to play an effective part in such a programme.     

Psoriasis of the dorsal surface of the tongue

Psoriasis is primarily an inherited inflammatory skin disease, it is characterized by erythemato-squamous lesions that usually involve elbows, knees and the scalp. Oral manifestations are rare in psoriasis, infact, oral psoriasis involves 2% of psoriatic patients and usually it is observed with the onset of cutaneous lesions and progresses with them. Differential diagnosis should be done for Reiter's syndrome, leukoplakia and geographic tongue. The authors describe a case of tongue psoriasis without cutaneous lesions.     

Measurement of the profile angle and the aesthetic analysis of the facial profile

Cephalometric measurement of the face in terms of aesthetics can be difficult and misleading due to the variability of the intra-cranial reference lines. Extra-cranial references are more accurate, but can be time-consuming to apply. The Aesthetic Horizontal is an intuitive datum line related to the 'photographic position' of the head, which is expedient in use and clinically relevant. A new and straightforward technique is presented for transferring the Aesthetic Horizontal directly from the patient to any recent radiograph, which can then be used as the reference line for an aesthetic analysis of the facial profile. The instrument used for measuring the profile angle and the transfer is readily constructed from a protractor and small weight. The technique can also be used to transfer any other orientation (e.g. Natural Head Position or Natural Head Posture) from the patient to a recent radiograph.     

Aneurysmal bone cyst of the coronoid process of the mandible

A rare case of aneurysmal bone cyst (ABC) located in the coronoid process of the mandible in a 12-year-old girl is presented. Treatment consisted of excision of the lesion through preauricular, submandibular and intraoral approach. An access osteotomy distal to second molar region was required to gain access to medial side of the coronoid process. To our knowledge, this is the third case of an aneurysmal bone cyst of the coronoid process of mandible. While examining a patient with a large expansile intrabony jaw cavity with thin peripheral bone, which is filled with blood without presence of bruit, thrills and pulse pressure, the diagnosis of aneurysmal bone cyst should be on top of the differential diagnosis list. Seventy-four to eighty-five percent of aneurysmal bone cysts of jaws occur in 10-20 years age group. Therefore, a pediatric dentist may be the first person to see such a lesion.     

Morphologic study of the mandibular fossa and the eminence of the temporomandibular joint in relation to the facial structures

To clarify the relationship between the temporal component of the temporomandibular joint and facial bone structure, we measured anthropologic craniometric points and the structure of the mandibular fossa, including the eminence in 33 Japanese male dry skulls, with a three-dimensional apparatus. The length from the articular tubercle to the medial glenoid tubercle is correlated with skeletal variables such as the length of the fossae, the width of the masseter origin, and the mandibular length. Therefore it appears that the frontal dimension is related to the facial development, which is attributable to bite force. Goniometrically, the angle between the line deepest point of the fossa—the midpoint of the eminence and the Frankfort horizontal plane (middle angle)—was negatively correlated only with the ANB angle, suggesting that a steeper middle angle of the eminence is related to a retrusive maxilla or protrusive mandible.(Am J Orthod Dentofac Orthop 1997;112:634-8.)     

Adenoid cystic carcinoma of the dorsum of the tongue: presentation of a case

Adenoid cystic carcinoma is the most frequent malignant neoplasm of minor salivary glands (76.5%); it is clinically characterized by slow growth, and its most frequent localization is the hard palate. Histopathologically it presents three patterns, cribriform, tubular and solid; the solid type is related to a poor prognostic contrary to the cribriform type, which has a better prognosis. Surgical excision with wide margins is the treatment of choice, if it metastasizes to lymph nodules, post surgical radiotherapy is recommended. A 19 year-old man presented a recurrent lesion on the dorsum of the tongue previously diagnosed as monomorphic adenoma. In a second biopsy it was diagnosed as adenoid cystic carcinoma. The following immunohistochemical studies were ordered: CALP, CEA, Epithelial Membrane Antigen, Glial Fibrilar Acid Protein, Ki67; all of these studies were positive and with different intensities, corroborating the diagnosis of adenoid cystic carcinoma. The patient had a recurrence after 2 years.     

Maximizing the physical use of the office

When referring to the physical plant in a dental practice, I am referring mainly to the use of dental chairs, because this is where dental practice production occurs. By maximizing the use of chairs or adding the necessary number of chairs to a practice, any office can grow and experience a proper patient flow. Since most offices have significantly high rates of no-shows, last-minute cancellations and overdue patients, the potential for growth is enormous. By using the schedule and chairs properly, the office has the opportunity to maximize production, create convenient appointments for patients and significantly increase practice profitability.     

Clinical evaluation of the marginal fit of cast crowns--validation of the silicone replica method.

Replication of the space between a tooth and its cast crown, using a light-body silicone supported by a heavy-body silicone, is a recognized technique to evaluate the quality of a restoration. This study validates a similar method that is of great clinical and experimental interest. Whatever the type of silicone used, comparison is possible between different technical procedures of crown elaboration (type of impression, type of material, method of spacing, etc.). If an appropriate silicone is used, the cement space may be reproduced and its thickness measured, whatever the localization (cervical, axial, occlusal).     

Radiographic study to assess the reliability of the Gillies approach for biopsy of the superficial temporal artery

Biopsy of the superficial temporal artery is often used in the diagnosis of giant cell arteritis, but at traditional sites there is a risk of injury to the facial nerve. Recently the Gillies incision has been suggested as an alternative means of access for the biopsy, but the anatomical basis of this has not been fully elucidated. We therefore undertook a radiographic review of 150 patients, and examining 300 vessels, to find out. Our results indicated that there is considerable variability in the position of the bifurcation of the superficial temporal artery, and so a Gillies approach may not be reliable, particularly if access to the bifurcation is required.     

颌骨神经鞘瘤的诊断与鉴别

颌骨神经鞘瘤是一种少见的来源于神经鞘细胞的良性肿瘤,临床上易造成误诊。其鉴别诊断对于选择正确的手术方式具有重要意义。加深对颌骨神经鞘瘤临床表现和影像学、病理、免疫组化各项检查的了解,有助于提高其诊治水平。本文就颌骨神经鞘瘤的临床特征及与成釉细胞瘤、神经纤维瘤、颌骨囊肿等的鉴别诊断作一综述。     

A survey on the degree of satisfaction of the readers of the Belgian Review of Dental Medicine

After a readers survey, we came to the conclusion that the readership of the 'RBMD' doesn't feel the necessity to make a lot of changes at the present formula. There is a demand to insert, beside the main topic, a complementary column with news from the universities and also a need for more clinical information.     

A trial of densitometry in the objective assessment of the x-ray image of the apices of the interdental membranes in periodontal lesions

The authors suggest a method to assess the quality of filling dental contact surfaces, based on determination of the relative contrast index (RCI) of the x-ray image of interdental septal apexes at the site of filled and intact teeth on the same image. Analysis of their own findings has lead the authors to a conclusion that assessment of the tooth filling with the use of periodontal and hygienic indexes is not strictly consistent because it is subjective, whereas the RCI permits a follow-up of changes in the mineral content of the bone in the examined site over time.