When it comes to instruments for clinical-diagnostic use, two things matter: 1. scientific validation - that is, assurance that the instrument actually measures the phenomenon being evaluated 2. repeatability of the measurement
Since dentists and physicians we deal with on a daily basis are very sensitive to these aspects, we decided to summarize in this article studies on which our technology is based.
How was Teethan born
Teethan® was born from the observation and scientific studies carried out by the research group of Prof. Virgilio Ferruccio Ferrario, at the Laboratory of Functional Anatomy of the Locomotor Apparatus (LAFAL) in the Department of Human Morphology, Faculty of Medicine, University of Milan.
This group conceptualized a new model for surface electromyography in the dental field based on a specific protocol that analyzes dental occlusion from a neuromuscular point of view.
Prof. Ferrario, in fact, thanks to his engineering as well as clinical background, had sensed that, in order to overcome the limitations that have always been imputed to electromyography technology, it was necessary to build a process of calibration and occlusal reset that would allow the examination to be standardized, i.e. to make measurements - taken on the same patient, time apart - comparable.
Based on the scientific findings of the team led by Prof. Ferrario, Teethan then developed a protocol, called the Teethan® Occlusal Test, divided into two phases.
The first, called Calibration, incorporates some of the concepts of the Meersseman test, also known as the occlusal memory cancellation test. Two cotton rolls are interposed between the patient's arches, distal to the canines, asking the patient to clench in maximum intercuspation for 5 seconds.
In the second phase - Natural Occlusion - the cotton rolls are removed and a new tightening in maximum intercuspation is performed lasting 5 seconds.
Data can be obtained by comparing the Calibration and Natural Occlusion tests. This comparison shows the influence that tooth contacts have on muscle patterns and viceversa, highlighting possible occlusal imbalances in the patient.
Reliability of the technology: data repeatability and operator independence
Ferrario's protocol, combined with our technological development, has overcome several of the limitations of surface electromyography.
First, the use of differential electrodes got most of the cross-talk components (interference from other neighboring biological components) out of the way.
Second, probe placement instructions, resulting from the identification of specific anatomical points, allow for the minimization of errors related to probe misplacement by different operators.
In this regards, the work of Ferrario et al. (2006) aimed to evaluate the variability of the measurement made by electromyography according to the above protocol.
In their work, a measure of variability and operator-dependence was done by performing three independent sessions of acquisitions, each performed on seven different subjects 48 hours apart. The accuracy and precision of the measure were quantified by appropriate statistical tools. For all indices, the scores exceeded the threshold - globally recognized - corresponding to a good level of accuracy.
Another interesting finding that emerged was the following: in all variables extracted and statistically analyzed, the interaction between "operator" and "operator-subject" were not statistically significant, demonstrating that the examination cannot be considered operator dependent.
Teethan in the clinic: TMD patients
Wanting to explore the clinical value of the Teethan® examination, a very interesting PhD study [b] compared healthy subjects and TMD patients, which in turn were divided into patients with osteoarthritis and patients with limited soft tissue damage. The patients were analyzed by Teethan® Occlusal Test and MRI.
The results of the study showed a significant correlation between the two instrumental tests in being able to correctly distinguish the two types of patients.
For this reason, the use of Teethan® has been proposed as an initial screening on patients with TMD, limiting the prescription of MRI only to cases where abnormalities are found with Teethan compared to reference values.
Teethan in the clinic: calibration of a splint
The work of Tecco et al. (2021) aimed, instead, to test Teethan® as a guide in splint adjustments, comparing the results of therapy with splints calibrated with Teethan and those with standard splints.
Selected patients complained of muscle-tensive headaches, associated with pain in the masticatory muscles during palpation, but also pain during mandibular movements. None of them had disc dislocations or degenerative joint disease.
Study group was given a modified splint until neuromuscular balance was achieved according to Teethan® Occlusal Test. Control group, on the other hand, received an oral device constructed to generate homogeneous contacts.
Although both oral devices had a positive impact on the health of patients in the two groups, the one calibrated with Teethan produced, eight weeks later, an improvement in masticatory muscle pain during palpation of 72% [e], migraines of 68.5% and functional pain of 66.6%. In contrast, the same parameters for the control group were 60%, 13%, 36%, respectively.
Thus, it emerges how the use of Teethan® in splint calibration allowed to:
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decrease the treatment time and
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increase its predictivity.
Teethan in the clinic: functionalization of prosthetic artifact
Occlusion with prematurity or unbalanced contacts, whether on natural teeth or prostheses, can result in mandibular torsion or unfavorable center of gravity. The resulting muscular alteration is not evident macroscopically, but may lead in the short to medium term to bony alterations.
The study by Tartaglia et al. (2014) analyzed patients with complete prosthetic rehabilitations, both during the treatment design and in subsequent follow-ups.
After implant placement, at one week after surgery, occlusal modifications - via with occlusal papers assessment - were made on patients until neuromuscular balance was achieved, as indicated by Teethan® Occlusal Test reports, also to identify the best functionally accepted vertical dimension.
At the one-year follow up with surface electromyography, the activity of the masticatory muscles, in addition to having retained its positive condition of the delivery of the final restoration, underwent a marked general improvement, undoubtedly due to the period of adaptation and training of the patient to his new occlusion and masticatory function.
Again, as with splint therapy, prior adoption of the Teethan® instrument allowed delivery of an artifact with high clinical predictivity.
References
[a] Ferrario, V. F. (2006). The influence of occlusion on jaw and neck muscle activity: a surface EMG study in healthy young adults. Journal of Oral Rehabilitation, 33(5), 341-348. https://doi.org/10.1111/j.1365-2842.2005.01558.x
[b] Lodetti, G. (2012). Indagini strumentali elettromiografiche in pazienti con disordini temporomandibolari. CORE. https://core.ac.uk/download/pdf/187905091.pdf
[c] Martino, T. G. (2014). Functional evaluation of implant supported prosthesis. Overdenture, 1(1). http://www.stomaeduj.com/wp-content/uploads/2015/08/Functional-evaluation-of-implant-supported-prostheses.pdf
[d] Tecco, S. (2021). Electromyography-Guided Adjustment of an Occlusal Appliance: Effect on Pain Perceptions Related with Temporomandibular Disorders. A Controlled Clinical Study. Diagnostics, 11(667), 1-11. https://doi.org/10.3390/diagnostics11040667
[e] Survey conducted by questionnaire administered to patients