Giulio Preti

Tooth loss and obstructive sleep apnoea

BackgroundComplete tooth loss (edentulism) produces anatomical changes that may impair upper airway size and function. The aim of this study was to evaluate whether edentulism favours the occurrence of obstructive sleep apnoea (OSA).MethodsPolysomnography was performed in 48 edentulous subjects on two consecutive nights, one slept with and the other without dentures. Upper airway size was assessed by cephalometry and by recording forced mid-inspiratory airflow rate (FIF50). Exhaled nitric oxide (eNO) and oral NO (oNO), were measured as markers of airway and oropharyngeal inflammation.ResultsThe apnoea/hypopnoea index (AHI) without dentures was significantly higher than with dentures (17·4 ± 3·6 versus 11·0 ± 2·3. p = 0·002), and was inversely related to FIF50 (p = 0·017) and directly related to eNO (p = 0·042). Sleeping with dentures, 23 subjects (48%) had an AHI over 5, consistent with OSA, but sleeping without dentures the number of subjects with abnormal AHI rose to 34 (71%). At cephalometry, removing dentures produced a significant decrease in retropharyngeal space (from 1·522 ± 0·33 cm to 1·27 ± 0·42 cm, p = 0·006). Both morning eNO and oNO were higher after the night slept without dentures (eNO 46·1 ± 8·2 ppb versus 33·7 ± 6·3 ppb, p = 0·035, oNO 84·6 ± 13·7 ppb versus 59·2 ± 17·4 ppb, p = 0·001).ConclusionThese findings suggest that complete tooth loss favours upper airway obstruction during sleep. This untoward effect seems to be due to decrease in retropharyngeal space and is associated with increased oral and exhaled NO concentration.

TNF‐α TGF‐β2 and IL‐1β levels in gingival and peri‐implant crevicular fluid before and after de novo plaque accumulation

AIMS The aim of this split-mouth study was to investigate levels of tumour necrosis factor alpha (TNF-alpha), transforming growth factor beta (TGF-beta2) and interleukin-1 beta (IL-1beta) in gingival crevicular fluid (GCF) and peri-implant crevicular fluid (PICF) after a 21-day-period of de novo plaque accumulation in the same patient. MATERIAL AND METHODS In 25 patients, samples of GCF and PICF were collected in the sulcus of the tooth and of the implant after professional hygiene. After the no-hygiene phase (21 days), second samples of GCF and PICF were taken. Third samples were collected after 69 days of re-establishment oral hygiene techniques. The crevicular fluids were used to determine the volume and the levels of TNF-alpha, TGF-beta2 and IL-1beta. RESULTS The volume of the crevicular fluids increased significantly after 21 days of plaque accumulation around teeth and implants and decreased significantly by 69 days. TNF-alpha and TGF-beta2 did not change significantly among the three different samples. A significant increase of IL-1beta was observed after plaque accumulation around the teeth GCF, whereas in the PICF the increase was not statistically significant. CONCLUSIONS These data suggest that increased volumes of GCF and PICF could be useful markers of early inflammation in gingival and peri-implant tissues. In the presence of de novo plaque, implants showed lower, and nearly significant, levels of IL-1beta compared with teeth.

Influence of the thickness of the resin palatal vault on the closest speaking space with complete dentures.

The closest speaking space (CSS) has been considered stable over time, and therefore useful to determine the vertical dimension of occlusion (VDO) in edentulous patients. Clemençon affirms that, in complete denture wearers, CSS is not constant but depends on the thickness of the resin palatal vault, and that is the air volume needed to pronounce words to remain constant. The aim of this study was to evaluate Clemençon hypothesis in a group of edentulous patients rehabilitated with traditional maxillary denture and mandibular implant anchored overdenture. The CSS was determined by means of a kinematics method using the Elite System(R) at 30, 60, 90, 180, 360 days from delivery. The CSS was assessed twice at each stage: with the unmodified denture and a second time after thickening the resin palatal vault by 2 mm with a calibrated wax layer. The CSS after thickening the resin palatal vault was wider. The wider CSS observed can be because of oro-sensory feedback excited by contact between tongue and palatal vault. As hypothesized by Clemençon thickening the resin palatal vault could be a useful procedure to increase the VDO, in cases in which it is too low from the aesthetic stand point.

Changes in the density of protein gene product 9.5-immunoreactive nerve fibres in human oral mucosa under implant-retained overdentures

Reduced oral sensitivity and impaired masticatory cycles have been demonstrated in edentulous humans wearing removable dentures, and there is some evidence that these patients have a decreased innervation of the oral mucosa. Clinical and electrophysiological evidence shows that sensory performance improves after oral rehabilitation with implant-retained overdentures. The aim of this study was to compare the density of mucosal innervation in edentulous patients with that in dentate controls and to evaluate changes in the number or type of sensory receptors following placement of endosseous implants in these edentulous individuals. The mucosal innervation was evaluated by immunohistochemical assays for the neurospecific marker protein gene product 9.5, and the innervation pattern was compared with that of dentate controls. Morphometric analysis of the immunohistochemical material demonstrated a decrease in numbers of sensory receptors in the mucosa of edentulous patients and a significant increase in the number of nerve fibres in the mucosa covering the distal edentulous mandibular ridges supporting the prostheses after implant-retained rehabilitation. In contrast, there were only minor increases in the number of nerves in the peri-implant mucosa. These changes in innervation appear to be related either to the new biomechanical situation created by implant support, which favours more physiological tissue conditions, or to an adaptive mechanism in the peripheral processing of sensory stimuli. These changes may explain, at least partially, the clinically observed differences in sensory skills before and after implant placement.

A clinical study of graphic registration of the condylar path inclination.

The angular values of the CSP registered from 390 patients and obtained by tracing a tangent to the graph with the GR were analyzed. The data subjected to statistical analysis gave a median angular value of the CSP equal to 33 degrees and showed a great median value dispersion. A low error index was obtained in tracing the tangent to the CSP tracing with the GR method. The angular values of the CSP were repeatable over time since the variations found were less than 5 degrees. Variations of the CSP greater than 5 degrees were noted after repeated registrations in patients with TMJ disturbances as well as in patients treated with complete dentures. These data show the necessity for an individual measurement of the CSP value, especially in patients who need extensive readjustments of the prosthesis.

Development of nerve fibres in the temporomandibular joint of the human fetus

The development of nerve fibres in the temporomandibular joint (TMJ) in relation to the development of bone, muscle and fibre components was investigated in human fetuses ranging from 9 weeks of gestation to birth. Immunohistochemistry for the glia-associated protein S-100 and for the neuro-specific marker protein gene product 9.5 (PGP 9.5) were used; specimens were compared to specimens of adult TMJ capsule and disc. At 9–10 weeks, a small number of neural elements are already present in the connective tissue around the joint and in the mesenchyme between the two articular blastemas from which the disc will differentiate. By 19 weeks many nerve fibres are clearly visible. Immunohistochemical results suggest diffuse disc innervation extending along the entire disc but not in the thin central area. More complex structures, i.e. encapsulated corpuscles, were also seen. The fetal disc appears highly innervated compared to adult tissue; already at this developmental stage morphology and distribution of nerves and corpuscles in the joint capsule are comparable to those in the adult joint. It may be concluded that the innervation of the TMJ is detectable from the end of the second month and that it develops fully between the third and the fifth month of gestation. Nerve endings in the disc are most numerous at 20 weeks, after which a progressive reduction, possibly secondary to the growth of articular tissues, is observed throughout the last trimester of fetal life and into adult life. The innervation of the lateral pterygoid muscle, on the contrary, is much less than that seen in adult muscles, even at full-term.

Statistical study of the angle formed by the lateral part of the mandibular condyle and the horizontal plane

The angle between the LCA and frontal plane and the inclination of the lateral part of the mandibular condyle and the horizontal plane were measured in a sample of the skulls used in the study. Correlation between the two angles was found to be almost insignificant. Fifty-eight percent of the TMJs had an inclination of the lateral part of the condyle less than 15 degrees. The maximum value for this angle was found to be 45 degrees, and the minimum was -6 degrees.

Lateral transcranial radiography of temporomandibular joints. Part I: Validity in skulls and patients

Left and right TMJs of 10 skulls and 15 patients (50 TMJs) were studied by means of OLTP and tomography to establish optimal condylar position in the glenoid fossae at maximum dental intercuspation. Two OLTP examinations of each joint were made and individualized by submental X ray and by fluoroscopy. A comparison of the recorded data showed fluoroscopy to give the better result. According to this study, OLTP individualized by fluoroscopy may be a useful tool in the determination of condylar position.

A graphic evaluation of the intermaxillary relationship before and after therapy with the Michigan splint

The effect of the Michigan splint was evaluated graphically in a group of 19 patients. Gothic arch tracings were registered before and after a period of therapy of 4 months, and the two tracings were compared photographically. The position of the apex of the Gothic arch was displaced in most patients, while the shape of the arch was more regular in almost all patients. The validity of the use of the Michigan splint was confirmed.

Consistency of performance of a new craniostat for oblique lateral transcranial radiographs of the temporomandibular joint

A new craniostat for use with OLTP radiography of the TMJ is described. In a clinical study of 20 patients the craniostat demonstrated a satisfactory consistency of radiographic reproduction.