[Evaluating the effectiveness of the new mouthguard design in athletes involved in power sports]. / Otsenka effektivnosti primeneniya novoi konstruktsii zubnoi shiny u sportsmenov, zanimayushchikhsya silovymi vidami sporta.

The aim of the study was to assess the effectiveness of the new mouthguard design for functional rehabilitation of dental system in athletes involved in contact power sports. The functional state of dental system was evaluated by interferential electromyography of masticatory muscles and Doppler ultrasound examination of periodontal tissues. Before mouthguard use the asynchrony of masticatory muscles was seen which was released after the mouthguard application: electromyographic activity of the left and right masticatory muscles was balanced and the decrease in biopotentials amplitude was found out. The mouthguard also caused no functional disorders in periodontal tissues.

Combined Mandibular Guidance Therapy in the Management of a Hemimandibulectomy Patient.

This case history report describes two different devices, maxillary ramp prostheses (MRP) and mandibular guide flange prostheses (MGFP), prescribed for managing a hemimandibulectomy patient's deviated mandible. The patient was given muscle reprogramming exercises with coordinated use of both guidance prostheses for 2 months, leading to improvements in both postsurgical mandibular deviation and occlusal equilibration. A successful intercuspal position was eventually accomplished through the use of the combination therapy. MRP and MGFP can be a useful approach to avoid mandibular deviation and compromised function following a partial mandibular resection.

Wear of ceramic and titanium ball attachments in subjects with an implant-retained overdenture: a controlled clinical trial.

STATEMENT OF PROBLEM: Loss of retention of implant-retained overdentures due to wear of the patrix or matrix of the attachment system is a common clinical problem. PURPOSE: The purpose of this controlled clinical trial was to compare the wear of ceramic and titanium ball attachments and their corresponding gold matrices after 1 year of clinical function in subjects with implant-retained mandibular overdentures. MATERIAL AND METHODS: Forty subjects who had been treated with a 2-implant-retained overdenture received either 2 ruby ball attachments (20 subjects) or 2 titanium ball attachments (20 subjects). The diameter of the ball attachments and the thickness of the matrix were measured optically before insertion and after 1 year of clinical function. Differences among groups were then compared with the Wilcoxon rank sum test (α=.05). To estimate any correlation between clinical parameters and wear, the Spearman rank test was used. RESULTS: There was no significant difference (P=.73) in the median wear of ball attachments for the titanium group (5.3 µm; median 1.3 µm) and for the ceramic group (1.3 µm; median 1.3 µm). In the ceramic group, a fracture rate of 30% was observed. The mean wear of the matrices in the titanium group was 3.1 µm (median 6.8 µm) and in the ceramic group 2.1 µm (median 3.4 µm), P=.01. No correlation was found between ball attachment wear and matrix insert wear (Spearman rank test). Wear of matrices was weakly correlated with an increase in divergence between implant axes in the sagittal plane (P=-.28 and P=.021). Ball attachment wear was associated with an increase in divergence between matrix axes in the sagittal plane (P=-.34 and P=.047). CONCLUSIONS: Matrices on ceramic ball attachments showed less wear than those placed on titanium ball attachments. However, the use of ruby ball attachments cannot be recommended because of a high fracture rate.

The muscle engram: the reflex that limits conventional occlusal treatment.

The engram (the masticatory "muscle memory") is shown to be a conditionable reflex whose muscle conditioning lasts less than two minutes, far shorter than previously thought. This reflex, reinforced and stored in the masticatory muscles at every swallow, adjusts masticatory muscle activity to guide the lower arch unerringly into its ICP. These muscle adjustments compensate for the continually changing intemal and external factors that affect the mandible's entry into the ICP. A simple quick experiment described in this article isolates the engram, enabling the reader to see its action clearly for the first time. It is urged that every reader perform this experiment. This experiment shows how the engram, by hiding the masticatory muscles' reaction (the hit-and-slide), limits the success of the therapist in achieving occlusion-muscle compatibility. This finding has major clinical implications. It means that, as regards the muscle aspect of treating occlusion, the dentist treating occlusion conventionally is working blind, a situation the neuromuscular school of occlusal thought seeks to correct. The controversy over occlusion continues.

Evaluation of treatment for functional posterior crossbite of the deciduous dentition using Planas' direct tracks.

BACKGROUND: Functional posterior crossbites are a common finding in children with deciduous teeth and must be treated as soon as they are diagnosed in order to avoid unwanted changes in normal growth and development patterns. OBJECTIVE: This study objective was to evaluate the changes caused by Planas' direct tracks treatment on the arch dimensions of patients with functional posterior crossbite in first dentition. MATERIALS AND METHODS: The sample consisted of 20 children, 4 to 6 years old, divided into two groups, paired up according to age and gender. Group test was composed of 10 patients with functional posterior crossbite treated with PDT. Group control consisted of 10 children with normal occlusion. The evaluation criteria were intercanine and intermolar distances and Carrea's analysis (arch perimeter). All data were collected by a pre-calibrated examiner on study casts obtained at baseline and after 4 months of treatment. The statistical analysis of the data was achieved using GraphPad InStat software, version 3.05 for Windows, with the level of significance set at 0.05. For the comparison between intercanine and intermolar distances, the Tukey-Kramer Multiple Comparisons test was used. When Carrea's analysis was considered, the Mann-Whitney test was used. RESULTS: At the beginning of the study, all the evaluated criteria showed lower mean values in patients with posterior crossbites, and significant differences between test and control groups were noticed (P<0.05). After the end of follow-up period, these differences could not be verified (P>0.05). CONCLUSIONS: Within the limits of the present study, it is possible to conclude that the treatment with Planas' direct tracks was able to give back the normal dimensions of deciduous arch in patients with unilateral functional posterior crossbites, thus making it possible a better growth pattern.

Immediate effect of the resilient splint evaluated using surface electromyography in patients with TMD.

The aim of this study was to analyze the immediate effect of resilient splints through surface electromyography testing and to compare the findings with the electromyographic profiles of asymptomatic subjects. The participants were 30 subjects, 15 patients with TMD (TMD Group) and 15 healthy subjects (Control Group), classified according to Research Diagnostic Criteria (RDC/TMD) Axis I. A resilient occlusal splint was made for each patient in the TMD Group from two mm thick silicon to cover all teeth. The EMG examination was performed before and immediately after installing the splint. Three tests were performed as follows: 1. Maximum Voluntary Contraction (MVC) using cotton rolls (standards test); 2. MVC in maximal intercuspation position; and 3. MVC with the splint in position. The EMG signal was recorded for five seconds. EMG indices were calculated to assess muscle symmetry, jaw torque, and impact. There was a statistically significant difference when comparing the results among the study groups. The symmetry index values in the Control Group were higher than the TMD Initial Group and similar to the TMD Group after the installation of the splint. The index values of torque were higher in TMD Initial Group when compared with the Controls. Impact values were lower than normal values in the TMD Initial Group and restored upon installation of the splint. The resilient occlusal splints may be used as complementary or adjunctive treatment of temporomandibular disorders.

Comparative study of intermaxillary relationships of manual and swallowing methods.

This study compared the mandibular displacement from three methods of centric relation record using an anterior jig associated with (A) chin point guidance, (B) swallowing (control group) and (C) bimanual manipulation. Ten patients aged 25-39 years were selected if they met the following inclusion criteria: complete dentition (up to the second molars), Angle class I and absence of signs and symptoms of temporomandibular disorders and diagnostic casts showing stability in the maximum intercuspation (MI) position. Impressions of maxillary and mandibular arches were made with an irreversible hydrocolloid impression material. Master casts of each patient were obtained, mounted on a microscope table in MI as a reference position and 5 records of each method were made per patient. The mandibular casts were then repositioned with records interposed and new measurements were obtained. The difference between the two readings allowed measuring the displacement of the mandible in the anteroposterior and lateral axes. Data were analyzed statistically by ANOVA and Tukey's test at 5% significance level. There was no statistically significant differences (p>0.05) among the three methods for measuring lateral displacement (A=0.38 +/- 0.26, B=0.32 +/- 0.25 and C=0.32 +/- 0.23). For the anteroposterior displacement (A=2.76 +/- 1.43, B=2.46 +/- 1.48 and C=2.97 +/- 1.51), the swallowing method (B) differed significantly from the others (p<0.05), but no significant difference (p>0.05) was found between chin point guidance (A) and bimanual manipulation (C). In conclusion, the swallowing method produced smaller mandibular posterior displacement than the other methods.

An investigation into explosive force variation using occlusal bites.

OBJECTIVE: To analyse the relationship between occlusion, posture and athletic performance in 15 professional basketball players. MATERIALS AND METHOD; The athletes were divided into two groups; the 8 subjects in the test group were fitted with retainers and the 7 subjects in the other group were used as control. All of the athletes underwent electromyographic and kinaesiographic examination with Transcutaneous Electrical Nerve Stimulation (TENS) before and after muscular relaxation to identify the myocentric position and to permit individualisation of the retainers. The effect of the intraoral devices on explosive force was evaluated via two functional tests: the countermovement jump (CMJ), and unilateral (UL) and bilateral (BL) stiffness jumps. The functional tests were carried out both before (T0) and immediately after (T1) fitting the retainer in an initial session, and then again, in a second session held two months later both without (T2) and with the retainer in place (T3). RESULTS: Statistical analysis of the data obtained revealed a statistically significant difference between T3 and T0, and between T3 and T2 in the study group, and between T0 and T3 in the control group; no statistically significant differences between the two groups were found. CONCLUSION: The results of this analysis lead us to conclude that the retainers had no effect on athletic performance, and that the improvement in this criteria noted in both groups in the second session was probably brought about by training.

Comparative study of intermaxillary relationships of manual and swallowing methods

This study compared the mandibular displacement from three methods of centric relation record using an anterior jig associated with (A) chin point guidance, (B) swallowing (control group) and (C) bimanual manipulation. Ten patients aged 25-39 years were selected if they met the following inclusion criteria: complete dentition (up to the second molars), Angle class I and absence of signs and symptoms of temporomandibular disorders and diagnostic casts showing stability in the maximum intercuspation (MI) position. Impressions of maxillary and mandibular arches were made with an irreversible hydrocolloid impression material. Master casts of each patient were obtained, mounted on a microscope table in MI as a reference position and 5 records of each method were made per patient. The mandibular casts were then repositioned with records interposed and new measurements were obtained. The difference between the two readings allowed measuring the displacement of the mandible in the anteroposterior and lateral axes. Data were analyzed statistically by ANOVA and Tukey's test at 5 percent significance level. There was no statistically significant differences (p>0.05) among the three methods for measuring lateral displacement (A=0.38 ± 0.26, B=0.32 ± 0.25 and C=0.32 ± 0.23). For the anteroposterior displacement (A=2.76 ± 1.43, B=2.46 ± 1.48 and C=2.97 ± 1.51), the swallowing method (B) differed significantly from the others (p<0.05), but no significant difference (p>0.05) was found between chin point guidance (A) and bimanual manipulation (C). In conclusion, the swallowing method produced smaller mandibular posterior displacement than the other methods.

Este estudo comparou o deslocamento mandibular a partir de 3 métodos de registro da relação cêntrica usando um jig anterior associado com: (A) guia da ponta do mento; (B) deglutição grupo controle (C) manipulação bimanual. As moldagens dos arcos maxilares e mandibulares foram feitas com hidrocolóide irreversível. Os modelos de estudo de cada paciente foram obtidos e montados em máxima intercuspidação como uma posição de referência no microscópio. Foram obtidos 5 registros de cada método em 10 pacientes. Os modelos mandibulares foram reposicionados com os registros interpostos e novas medidas foram obtidas. A diferença entre as duas leituras permitiu a medida do deslocamento mandibular nos eixos ântero-posterior e laterais. ANOVA não demonstrou diferença estatisticamente significativa entre os 3 métodos em relação ao registro do deslocamento lateral (A = 0,38 ± 0,26, B = 0,32 ± 0,25 e C = 0,32 ± 0,23). Quanto ao deslocamento anteroposterior, ANOVA e o teste de Tukey (a=0,05) indicaram diferença estatisticamente significante entre os três métodos (A=2,76 ± 1,43, B=2,46 ± 1,48 e C=2,97 ± 1,51). Não houve diferença estatisticamente significante entre A e C. A deglutição propiciou menor deslocamento mandibular posterior que os outros métodos.

Occlusion splint therapy in patients with craniomandibular disorders (CMD).

The etiology of craniomandibular disorders (CMD) is multi-factorial and the treatment should be selected with recognition of the different factors. The aim of the study was to investigate the influence of occlusion splint therapy (Michigan splint), physical exercises and transcutaneous nerve stimulation (TENS) on CMD symptomatology. At the Clinic of Maxillofacial Surgery in Belgrade, in the period from May, 2001-December, 2003, 168 patients were examined by the CMD working group. This group, comprised of different specialties (maxillofacial surgeon, prosthodontist, orthodontist, neurologist, psychiatrist and physiatrician), enabled multidisciplinary treatment of CMD patients according to the guidelines given by American Academy for Craniomandibular Dysfunctions. In all, a total of 30 patients with prevalent muscular tensions among other CMD symptoms were included in this study. The examination form according to Fricton and Shiffman for Craniomandibular Index (CMI) was used in order to evaluate the function of Craniomandibular system before and after therapy.A statistically significant difference (t = 8,735; P < 0,001) between the average values for CMI of patients before (0,2297 +/- 0,0827) and after therapy (0,1002 +/- 0,0479) was observed. Performed treatment resulted in complete response (pain relief and absence of CMD symptoms and signs) in over than 80% of patients and could be considered as a method of choice in reversible occlusal therapy.

Definition of erosion and links to tooth wear.

Erosive tissue loss is part of the physiological wear of teeth. Clinical features are an initial loss of tooth shine or luster, followed by flattening of convex structures, and, with continuing acid exposure, concavities form on smooth surfaces, or grooving and cupping occur on incisal/occlusal surfaces. Dental erosion must be distinguished from other forms of wear, but can also contribute to general tissue loss by surface softening, thus enhancing physical wear processes. The determination of dental erosion as a condition or pathology is relatively easy in the case of pain or endodontic complications, but is ambiguous in terms of function or aesthetics. The impact of dental erosion on oral health is discussed. However, it can be concluded that in most cases dental erosion is best described as a condition, with the acid being of nonpathological origin.

The CICERO system for CAD/CAM fabrication of full-ceramic crowns.

The CICERO method of crown fabrication consists of optically digitizing a gypsum die, designing the crown layer buildup, and subsequently pressing, sintering, and milling consecutive layers of a shaded high-strength alumina-based core material, a layer of dentin porcelain, and a final layer of incisal porcelain. Final finishing is performed in the dental laboratory. The CICERO method allows efficient production of all-ceramic restorations without compromising esthetics or function. This article reviews the process involved in the fabrication of a CICERO crown.

Observations on the correlation between posture and jaw position: a pilot study.

The aim of this pilot study was twofold. The first was to show a method for having an objective and dynamic analysis of body posture, evaluating weight distribution and its connections with different mandibular positions. The second was to verify if a neuromuscularly stimulated occlusal position, called myocentric occlusal position, is associated with a positive or negative postural charge. For the second aim a group of 20 subjects (including both males and females), was chosen. Posture of each subject was analyzed in three different conditions: centric occlusion, rest position and myocentric position. To evaluate the dynamic of posture a platform capable of measuring the weight on the feet supporting points and the related variations during time of observation and the swinging of body barycenter was used. The data showed that there is an improvement in the position of the barycenter from the centric occlusion to the myocentric position. Such an improvement can't be observed from the intercuspal position to the rest position. The results of this pilot study are discussed.

The role of bioelectronic instruments in the management of TMD.

Temporomandibular disorders (TMD) comprise a group of conditions that can affect the form and function of the temporomandibular joint (TMJ), masticatory muscles and dental apparatus. Proper management of TMD by the dentist requires accurate appraisal of the status of the patient's dentition, TMJ and associated neuromuscular apparatus. Certain predefined standards or parameters of function/dysfunction are accepted by the profession. Electronic instrumentation provides objective measurement of many of these biological phenomena, and thus can be used throughout treatment for critical analyses that monitor and enhance treatment efficacy. A treatment protocol for TMD is presented that uses electronic instrumentation to establish a neuromuscular occlusion.

Clinical study of location and reproducibility of three mandibular positions in relation to body posture and muscle function.

Clinical studies have confirmed the adequate reproducibility of both centric occlusion and centric relation when used as reference positions during treatment; however, the reproducibility of the neuromuscular position has been found inadequate. This study evaluated the location and reproducibility of these three mandibular positions in relation to body posture, sitting and supine, and bilateral muscle activity before and after the insertion of a flat mandibular positioning device equilibrated to balance the muscle functions, as shown by two electromyography biofeedback instruments. Intraoral recordings were made in 11 young subjects with complete natural dentition. Acrylic resin clutches that supported a screw point in the maxillary arch and painted glass in the mandibular arch were used and positioned not to interfere with the occlusion. The distances of the screw scratch from two of the edges of the painted glass were used to measure the anteroposterior and mediolateral locations with a micrometer. The reproducibility was evaluated by measuring the scratch surface by measuring the weight of the print cutouts made from photographs of the scratches taken with a stereoscope. The location and reproducibility of centric occlusion and centric relation were not affected by body posture. A more precise posterior neuromuscular position was obtained in the supine position. The insertion of a mandibular positioning device did not affect centric occlusion but gave a more precise centric relation. Neuromuscular position became as precise as centric occlusion and was located anteroposteriorly between centric occlusion and centric relation.

The effect of four jaw relations on electromyographic activity in human masticatory muscles.

Significant differences were found in the electromyographic (EMG) activation between the masseter and temporalis muscles for the leaf gauge (LG), manually manipulated (CR) and neuromuscular (NM) bite positions during maximal static clench. The LG position consistently demonstrated the lowest EMG activity, while the NM position displayed the highest degree of muscle activity. Similarly, the ratio of the masseter/temporalis EMG activity during maximal clench was lower for the LG and CR positions and highest for the NM position. These data indicate that the NM position produced the greatest total muscle recruitment, with more masseter involvement during maximal clench, and enabled the subjects to generate greater clenching forces in the NM position as compared to the LG and CR positions.

[The usage of E.M.G. in the dental research and the clinical practice]. / E chrese tes elektromyographias sten odontiatrike ereuna kai ten klinike praxe.

The first part of this review, refers to the use of electromyography (EMG) in studying the stomatognathic system. EMG is used for the study of function and fatigue of the masticatory muscles, the recording of centric relation etc. The behavior of the masticatory muscles (especially of the masseter and the temporalis) in the cases of TMJ dysfunction are also reviewed. In the second part, there is a description of the use of EMG biofeedback in the treatment of TMJ dysfunction, myofacial pain and bruxism. Finally, there is reference to the portable modular EMG biofeedback units.

Effect of topical cheek surface anesthesia on isometric contractions of the human masseter muscle.

To study the possibility of interactions between buccal cutaneous sensory receptors and voluntary maximum isometric contractions of the masseter muscles, six adult subjects exercised maximum teeth clenching before and after spraying the right cheek surface with aerosol containing 20% benzocaine. The right cheek and masseter muscle served as the experimental side, the left cheek and masseter muscle as the control side. Isometric motor outputs, on the right and left sides, were monitored by integrated surface electromyography over periods of 10 seconds. Topical surface anesthesia provided no evidence of motor modulation by cutaneous tactile receptors. Before and after anesthesia, the two muscles showed nearly identical and well-coordinated motor innervation patterns. It is suggested that the cortical motor commands of maximum isometric contractions, with recruitment of practically all available motor units, overrule all modulatory inputs except those of fatigue.