/home/opencode/cpanel/stomaeduj_hacked/uploads/Article_7_3_6.pdf OCCLUSION AND TMJ www.stomaeduj.com THE INFLUENCE OF OCCLUSION ON MASTICATORY Original Articles EFFICIENCY CONSIDERING RELEVANT INFLUENCING FACTORS Gregor Slavicek1,2,a* 1 Steinbeis Transfer Institute Biomedical Interdisciplinary Dentistry, Steinbeis University Berlin, DE-12489 Berlin, Germany 2 OREHAB-Minds GmbH, DE-70567 Stuttgart, Germany MD, DDS, MSc, Director and Head, CEO and Head; e-mail: gregor.slavicek@stw.de; ORCIDiD: https://orcid.org/0000-0003-2454-4048 a ABSTRACT https://doi.org/10.25241/stomaeduj.2020.7(3).art.6 Introduction The role of the occlusal quality as a relevant factor for mastication is controversially discussed. This paper aims to determine the role of the occlusion given the influencing factors. The correlation between the subjective evaluation of treatment needs and objective chewing test results are assessed. Methodology 842 participants (female n=460, 54.5%; male n=382, 45.4%) performed a standardized chewing test. The participants’ occlusal quality, angle classification, age, gender, treatment needs and intraoral status were recorded. The participants were instructed to break down the standardized chewing tests units. The particles were collected in a sieve and placed on a calibrated acquisition board. Standardized images were analysed, measuring the areas of each particles in mm2. Null Hypotheses were tested with the Kruskal-Wallis tests and post hoc tests with Bonferroni correction, to be rejected at p≤0.01. Results The occlusion quality has a significant impact on the chewing efficiency (p≤0.001), but angle classification only to some extent. Age (p≤0.001) and gender (p≤0.001) are important intrinsic factors. Fixed prosthodontics do not reach the chewing performance of natural occlusion (p≤0,01). The subjective clinical assessment of treatment needs correlates in categories with strong differentiations (p≤0,001), but not if only minor differences are asserted (p≤0,515). Conclusion The occlusion quality has a significant impact on the chewing efficiency. Masticatory performance is highly dependent on the natural or artificial chewing surface morphology. Age, gender and the intraoral status are important intrinsic factors. The maintenance of a sufficient functional oral status is a crucial task in the care of the aging population. KEYWORDS Chewing Efficiency; Chewing Surface Morphology; Dental Occlusion; Mastication; Standardized Chewing Test. 1. INTRODUCTION the gastrointestinal tract. This mechanical fragmen- tation makes digestion more efficient [1]. The 1.1. Aim of mastication provision of energy and essential nutrients can The aim of a masticatory process is to comminute be guaranteed by the regular intake of smaller, food as homogeneously as possible, to moisten but mechanically processed amounts of foods. the food bolus with saliva and to prepare it for The masticatory process poses a major functional swallowing. The principle of the mechanical proce- challenge to the stomatognathic system for its ssing of food is found in all mammals, including whole lifetime [2]. Mastication exerts a substantial humans. From an evolutionary perspective, it is an effect on human health [3]. Food, inserted in the advantage to comminute food prior to digestion in mouth, is normally known. So, an expectation OPEN ACCESS This is an Open Access article under the CC BY-NC 4.0 license. Peer-Reviewed Article Citation: Slavicek G. The influence of occlusion on masticatory efficiency considering relevant influencing factors. Stoma Edu J. 2020;7(3):197-207. Received: August 24, 2020; Revised: September 11, 2020; Accepted: September 12, 2020; Published: September 14, 2020 *Corresponding author: Dr. Gregor Slavicek, MD, DDS, MSc, CEO and Head; OREHAB-Minds GmbH, Zettachring 2, DE-70567 Stuttgart, Germany Tel./Fax: +49-7307-24922-11; e-mail: g.slavicek@orehab-minds.com Copyright: © 2020 the Editorial Council for the Stomatology Edu Journal. Stoma Edu J. 2020;7(3): 197-207 pISSN 2360-2406; eISSN 2502-0285 197 Slavicek G. www.stomaeduj.com Original Articles Figure 1a. Overall chewing efficiency vs. occlusal quality. Figure 1b. Right side chewing efficiency vs. occlusal quality of the right side. exists, reinforced by visual, olfactory, and gustatory sensations. Based on this preliminary information, patterns can be retrieved from memory that are optimally adapted to the food. If the feedback from the intra- and extraoral proprioceptors differs from the expectations, the masticatory pattern will be adapted [4]. These feed-back mechanisms react to the so-called mouth feel of food (Tab.1). 1.2. Teeth are highly specialized tools Teeth are used as highly specialised tools when Figure 1c. Left side chewing efficiency vs. occlusal quality of the left side. food needs to be comminuted. Teeth have adapted over the course of evolution to the needs of the and a reduced chewing ability is reported more mammalian species in an astonishing variety of forms often in patients with CMD symptoms [11]. The [5]. A food bolus positioned between the dental masticatory patterns of children with deciduous arches is broken down mechanically. The structures teeth are characterised by wide lateral movements of the occlusal surface of the teeth tend to be flat to the working side on opening and a more inwardly with prominent enamel ridges in many mammals, directed path during the closing phase of the masti- so the masticatory forces have an optimal effect on catory cycle. In adults, on the other hand, the opening food [6]. The huge variety in the morphology of the movement are performed in the median-sagittal masticatory surfaces can be explained by adaptation plane. The closing movement is characterised by to extrinsic factors [7]. a wide lateral movement to the working side. The Just like tooth morphology, the shape of the occlusal closing paths of the molars on the working side surfaces, and the spatial arrangement of the teeth move from a retrusive, inferior and lateral position differ considerably in many species, oversimplified forward, upward, and inward [12,13,14]. In children, traceable on the carnivores-herbivores differences. occlusion is approached directly from an opened The teeth of carnivores (meat-eaters) are completely mandibular position in the median sagittal plane. different from the teeth of herbivores (plant-eaters) The movements of molar cusps on working and non- [8]. Catching and retaining prey are tasks that requ- working sides follow different paths in children and ire considerable strength and robustness of the adults [15]. carnivores stomatognathic system. The teeth of carnivores chisel off large pieces, which are then 1.3. Gender differences swallowed entirely. The actual process of digestion Women’s and men’s dietary habits differ considerably is performed in the digestive tract. Herbivores have [16]. If the dynamics of the masticatory process totally different demands on teeth and the chewing are considered and correlated with gender, males organ. Leaves and twigs can be grasped easily. perform faster and wider chewing cycles. The dura- Excessive mechanical processing is performed in the tion of a single chewing cycle is extended in females oral cavity. The tooth surfaces are moved against one [17]. Obviously, males develop higher masticatory another in a distinct direction – so plant fibres are forces than women. What is noteworthy, however, is mechanically comminuted. The direction of chewing that it is not possible to infer any direct correlation movements is adapted to the structure of the tooth between the masticatory force and muscle activity surfaces [4]. [18]. Nevertheless, many other factors such as age, Unphysiological chewing movements may have dental status, prosthetic status overlap gender- serious effects on teeth, periodontium, and the specific differences in chewing [19]. In addition, neuromuscular system [9]. The relationship with health conditions, such as facial osteoporosis, craniomandibular dysfunctions (CMD) is also a may impair masticatory muscles patterns and subject of discussion [10]. A preferred chewing side performance [20]. 198 Stoma Edu J. 2020;7(3): 197-207 pISSN 2360-2406; eISSN 2502-0285 The influence of occlusion on masticatory efficiency www.stomaeduj.com Original Articles Figure 2a. Soft, medium and hard standard chewing test unit vs. overall Figure 2b. Soft, medium and hard standard chewing test unit vs. overall occlusal quality. occlusal quality in females. 1.4. Chewing tests - requirements to be fulfilled A clinical test measuring chewing ability must consider extrinsic and intrinsic factors. Extrinsic para- meters include food properties. Intrinsic parameters are among others age, gender, dental status. In addition, chewing tests units must be chosen that pose a similar challenge on the masticatory organ as natural foods. 1.4.1. Fragmentation methods as the golden standard Significantly different methods to measure chewing ability are described in the specialized literature. Bearing in mind that mastication is intended to reduce Figure 2c. Soft, medium and hard standard chewing test unit vs. overall food to as many equally sized particles as possible, occlusal quality in males. methods that determine the degree of comminution clinical practice. Modern technologies such as opti- are the methods of choice. SCTU is chewed within cal scanning and/or imaging techniques can be a defined time span and then spat out [5,27]. The used to overcome such burdens. The comparison number, area and distribution of the particles can be of sieving with optical methods validates both determined for analysis. An alternative method is to methods and demonstrates comparable reliability measure the time span required to achieve a certain and accuracy of information technology-based degree of comminution. However, this requires chewing fragmentation test procedures with sieving several masticatory series of increasing duration to methods [30]. check when the degree of comminution is in line with the expectations [12,27,28]. The degree of 1.5. Factors influencing chewing efficiency comminution can be determined in various ways, How well food is comminuted depends on many among which the sieving method has become factors. Manifold parameters such as dental status, established as a valid model. Sieving methods are quality of chewing surface morphology, chewing used to determine the distribution of the particle forces, harmony of mandibular movements and sizes of a granular material. This involves arranging co-ordination capacity of the neuromuscular several test sieves with decreasing mesh widths on system must be considered. These parameters top of one another. The quantity of the test material are commonly subdivided into intrinsic (e.g. in each sieve can then be determined – for example demographic attributes) and extrinsic (e.g. food by weighing the dried mass per sieve. In this way, properties) factors. conclusions can be drawn about the efficiency of the 1.5.1. Intrinsic factors comminution process and hence the masticatory Salivation and saliva quality affect the outcome efficiency from the homogeneity of the particle of the masticatory sequence [31]. The degree of size. This involves a consideration of the number of moisture of the food and in some cases additional particles, the size of the particles and the ratio of fluid intake during mastication contribute to a the particle sizes in the food bolus. The methods change in the masticatory performance [32]. Age for determining the masticatory ability based on and gender are intrinsic modulators as well. All the sieving technique principle are also referred to these factors affect mastication [33]. On the other as fragmentation procedures [29]. Sieving methods hand, the effect of age may not be as pronounced as are time consuming and not appropriate for routine initially assumed. The number of masticatory cycles Stoma Edu J. 2020;7(3): 197-207 pISSN 2360-2406; eISSN 2502-0285 199 Slavicek G. www.stomaeduj.com Original Articles Figure 3a. Rigt side chewing efficiency vs. Angle classification on the Figure 3b. Left side chewing efficiency vs. Angle classification on the left right side; female vs. male. side; female vs. male. Table 1. Overview of the perceived properties of food that have a significant influence on subjective perception and the so-called mouthfeel. The subjective taxation of food ingested in the mouth is by no means constant from the time it is placed in the mouth until it is swallowed, but can change considerably during a chewing sequence. required to comminute a standardised food unit such as elasticity, springiness, texture, chewability increases with age, but the capacity for individual and cohesiveness cause changes in masticatory adaptation to the properties of the food persists behaviour. By changing food texture, it is possible even in elderly subjects. The stomatognathic system to alter masticatory behaviour. The timespan, until remains relatively well preserved if people retain a food bolus is swallowed, can be varied by food their dentition. This contrasts with other areas of the properties. Slower eating, which can be induced locomotor apparatus, which may be because the by a change in texture, thus produces a reduction stomatognathic apparatus is used every day, even in energy intake without affecting post-meal in people who already have difficulties walking [28]. satisfaction [35]. 1.5.2. Extrinsic factors Consensus exists to define the task of the Like the parameters attributable to the individual, masticatory process as the oral fragmentation of food has a considerable effect on the process of food to form a semi-liquid bolus for swallowing, a mastication. The masticatory force, the vertical and SCT should reflect on this: SCTU to be comminuted lateral excursions of the masticatory movements, into as much and as equally sized particles as the rate of individual masticatory cycles and the possible within a predefined length of the chewing frequency of mastication are parameters affected sequence. Chewing media that do not degrade, by food properties. The rheological properties of such as chewing gum, do not meet this fundamental food are controlled by mechanisms localised in requirement [18]. Additionally, understanding chew- the brainstem [2,21,22,24,34,35,36]. Varying food ing efficiency is not possible with one chewing textures can be used to influence dietary habits, sequence only (preferred chewing side problem). such as more rapid or slower mastication, but in Intra-individual comparisons such as right vs. left vs. this case, hardness is not the most critical factor. bilateral or soft vs. medium vs. hard based on several Food properties such as plasticity, elasticity, and chewing sequences provides an in-depth review for size have a direct effect on the afferent input signal clinicians and a better understanding for laypersons in the central nervous system. Instead, parameters (patients and relatives). 200 Stoma Edu J. 2020;7(3): 197-207 pISSN 2360-2406; eISSN 2502-0285 The influence of occlusion on masticatory efficiency www.stomaeduj.com Original Articles Figure 4. Chewing efficiency and age (n=851). Table 2. The categories to assess occlusal quality, using photo´s for area of particles, respectively) is the same for females classification: no to distinct occlusal structures. The evaluation was and males. performed per quadrant. H05: The subjective assessment of treatment needs by the investigator correlates with the distribution of number of particles (or mean area of particles, respectively). H06: The distribution of number of particles (or mean area of particles, respectively) is independent from the maxillary and mandibular status. 2. METHODOLOGY The participants were instructed to try to break down the standardized chewing tests units (SCTU) into as many small pieces as possible. After 30 seconds the participants spited out the particles into a sieve. The particles were placed on a acquisition board with calibration elements. Standardised images are then taken and analysed using a validated software application. The surface areas of each of the particles are measured and displayed in mm2. The a priori determined Null Hypotheses were tested with the Kruskal-Wallis test followed by an applicable post hoc 1.6. Research question test with Bonferroni correction for repeated tests, to The role of the quality of occlusion as an influencing be rejected if p≤0,01. Data are collected as part of factor of masticatory efficiency is controversially the BID-11400 study, multicentre and multinational discussed in the dental community. The aim of this clinical trial to evaluate masticatory functionality article is to contribute to a better understanding and quality of life. The study is approved by the of whether occlusion significantly influences Ethic Committee of University Cologne, Nr. 16-082, chewing efficiency or not and to highlight possible 15. May 2017. This evaluation includes data form cofounders such as angle classification, age, gender, projects which were recorded within the BID-11400 treatment needs and intraoral status. study, but solely by students as part of the Master The null hypotheses tested are: of Science curriculum - Biomedical Interdisciplinary H01: The distribution of number of particles (or mean Dentistry at Steinbeis University Berlin. The data area of particles, respectively) is the same across were collected between 2017-2019. A total of 851 categories occlusal quality. data sets were used for these analyses. H02: The distribution of number of particles (or mean Occlusal quality was judged by the investigator, area of particles, respectively) is the same across using reference pictures, and determining occlusal categories Angle classifications. quality for each quadrant (Tab. 2). The overall occ- H03: The distribution of number of particles (or mean lusal quality and the quality of occlusion on the area of particles, respectively) is the same across age right and left side were consolidated for the analytic groups. process. Gender and year of birth were recorded for H04: The distribution of number of particles (or mean each participant. The age was calculated, and each Stoma Edu J. 2020;7(3): 197-207 pISSN 2360-2406; eISSN 2502-0285 201 Slavicek G. www.stomaeduj.com Original Articles Figure 5a. Overall chewing efficiency vs. age; females vs. males. Figure 5b. Overall chewing efficiency vs. age; females. participant was assigned to one age group: 18-24y; 25-34y; 35-44y; 45-54y; 55-64y; 65-74y; 75-84y. The treatment needs were assessed by the investigator. The assessment was made in the following categories: clear indication for treatment; average treatment indication; minor treatment indication; no treatment indication. The maxillary and mandibular status was captured, for this analysis, only 3 categories have been used: Prevalence of natural teeth with minimal presence of restorations; Prevalence of natural teeth with the presence of fillings and partial crowns; Fixed prosthesis with bridges and crowns including Figure 5c. Overall chewing efficiency vs. age; males. implants. The chosen procedure should reflect the real clinical situation. chewing test (SCT). In addition, data on the The standardized chewing test (SCT) was performed participant´s occlusal quality, angle classification, as follows: The patient is instructed on how to carry age, gender, treatment needs and intraoral status out the required nine masticatory sequences, each were recorded. The age distribution was as follows: lasting 30 seconds. SCTU are used with tree different 18-24y (n=124, 14,7%; 26-34y (n=160, 19%); 35-44y types of hardness. The basic mass for the SCTU is a (n=126, 15%); 45-54y (n=110, 13,1%); 55-64y (n=84, standard formula used and approved commercially 10%); 65-74y (n=131, 15,6%); 75-84y (n=85, 10,1%), for fruit gum. The difference in hardness is achieved >85y (n=22, 2,5%). Age group >85y was excluded for by the amount of gelatin added. Three different this analysis due to the low percentage. colors are used – algae extract for the green/soft, carrot/pumpkin extract for the yellow/medium and 3.1. Quality of occlusion and Chewing efficiency elder for the red/hard. The SCTU are equally flavored The H01 “The distribution of number of particles with strawberry essence. The chosen shape of the (or mean area of particles, respectively) is the same SFM is slightly cylindrical, with a diameter of 2 cm across categories occlusal quality” was tested with and a height of 1 cm [5,37]. a Kruskal-Wallis test followed by a post hoc test The instruction to the patient is: “Try to break down with Bonferroni correction for repeated tests. The the test item into as many small pieces as you can". difference between the occlusal categories was The patient should chew in a concentrated way significant (p<0,001). The post hoc analysis shows and should not be or get distracted while chewing. the marked difference between all four occlusal After 30 seconds the patient spits out the particles categories. This applies to overall chewing efficiency into a sieve. The particles per chewing sequence as well as for the right and left sides, where only are placed on a recording plate with calibration the masticatory test results for that side were used elements and spread out so that the particles are for the analysis (Fig.1a,1b,1c). Considering occlusal at least 1 mm apart. Standardised images are then quality, an almost linear reduction of the numbers of taken and analysed using a software application. The particles can be seen in especially in females, but not surface areas of each of the particles are measured in males (Fig. 2a,2b,2c). and displayed in mm2. From this information the following key data can be determined: number n, 3.2. Influence of Angle’s classification on masticatory area, and ratio of the particle sizes. efficiency The H02 “The distribution of number of particles 3. RESULTS (or mean area of particles, respectively) is the same A sample of n=842 participants (female n=460, across categories Angle classifications” was tested 54,6%; male n=382, 45,4%) performed a standardized using a Kruskal-Wallis test followed by a post hoc test 202 Stoma Edu J. 2020;7(3): 197-207 pISSN 2360-2406; eISSN 2502-0285 The influence of occlusion on masticatory efficiency www.stomaeduj.com Original Articles Figure 6. Overall chewing efficiency vs. gender. Figure 7. Influence of soft and hard standard chewing test units on chewing efficiency, per gender. with Bonferroni correction for repeated tests. The differences between the Angle classifications were significant (p<0,001). The post hoc analysis showed that dental classes I, II/1 and II/2 do not differ. Angle’s class III differs significantly from the other dental classes. This applies to both the right and left sides, where only the masticatory test results for that side were used for the analysis (Fig. 3a,3b). However, the results should be interpreted cautious since class II malocclusions were underrepresented in the study Figure 8. Chewing efficiency vs. assessment of treatment needs by sample. Hence it cannot be confirmed that Angle’s investigators. classification has a major impact on masticatory performance. particles, respectively)” was tested with a Kruskal- Wallis test (p<0.001) followed by post hoc test with 3.3. Influence of Age on masticatory efficiency Bonferroni correction for repeated tests. The results The H03 “The distribution of number of particles are presented in Fig.8. The post hoc analysis showed (or mean area of particles, respectively) is the same that objective masticatory efficiency coincides with across age groups” was tested with a Kruskal-Wallis the assessment of treatment need for the extreme test (p<0.001) followed by a post hoc test with categories “no treatment indication” and “clear Bonferroni correction for repeated tests. The results indication for treatment” only, while no significant are presented in Table 3. The influence of age quoted difference (p=0.515) was found between the in the literature can be confirmed based on the “average” and “minor” treatment indication groups. results of this study. It can be inferred that intraoral factors, especially in the elderly, significantly exceed 3.6. Maxillary and mandibular status and masticatory the influencing factors age on chewing efficiency efficiency and should be taken into consideration in treatment The categories “Prevalence of natural teeth with strategies of an elderly population. minimal presence of restorations (upper jaw: n=475; lower jaw: n=494)”, “Prevalence of natural teeth 3.4. Gender-specific differences with the presence of fillings and partial crowns The H04 “The distribution of number of particles (upper jaw n=90; lower jaw n=103)” and “Fixed (or mean area of particles, respectively) is the same prosthesis with bridges and crowns including for females and males” was tested with a Mann- implants (upper jaw n=178; lower jaw n=155)” are Whitney-U test (p<0.001). A SCT test based on incorporated in this analysis. The analysis was done nine chewing sequences shows that men generate separately for the upper and lower jaws. The H06 markedly more (male 129 vs. female 110) and smaller “The distribution of number of particles (or mean particles (male 107.25mm2 vs. female 125.68mm2) area of particles, respectively) is independent from than women (Fig.6). The difference is significant the maxillary and mandibular status” was tested. (p=0.002 for the number of particles, p<0.001 for the The highest masticatory performance is achieved by particle area). This overall difference between males natural teeth with minimal presence of restorations, and females can also be seen for soft and hard SCTU followed by natural teeth with fillings and partial (Fig.7). crowns. The results apply for upper (Fig.9a) and lower jaw (Fig.9b). Fixed prosthetic restorations such 3.5. Assessment of treatment needs and chewing as crowns and bridges, including implant-supported efficiency fixed dentures, do not reach the results of natural The H05 “The subjective assessment of treatment occlusion. The Mann-Whitney-U test was used to test needs by the investigator correlates with the for significance. For maxillary status no significant distribution of number of particles (or mean area of difference was found between “Prevalence of natural Stoma Edu J. 2020;7(3): 197-207 pISSN 2360-2406; eISSN 2502-0285 203 Slavicek G. www.stomaeduj.com Original Articles Figure 9a. Overall chewing efficiency vs. current status of the upper jaw Figure 9b. Overall chewing efficiency vs. current status of the lower jaw (natural occlusal and fixed prosthesis only). (natural occlusal and fixed prosthesis only). Table 3. Results of a one-way ANOVA on ranks (Kruskal-Wallis test) followed by a post hoc test with Bonferroni correction for repeated tests to test whether chewing efficiency is different in age groups. In elderly, the age-related decline of chewing performance seems to be altered by other influencing intrinsic factors. teeth with minimal presence of restorations” and Maxillary and mandibular teeth are best aligned with “Prevalence of natural teeth with the presence of each other in a class I occlusion, assuming regular fillings and partial crowns”. A significant difference tooth shapes. What is known as a class II or class III was found between “Prevalence of natural teeth malocclusion does not exist in primates – this would with minimal presence of restorations” and “Fixed obviously be a distinct disadvantage in the search prosthesis with bridges and crowns including for food and consumption of food. Malocclusion implants” (p<0.001). A significant difference was seems to conflict with the evolutionary concept of found between “Prevalence of natural teeth with survival of the fittest. In humans, malocclusion has the presence of fillings and partial crowns” and ceased to be a selection criterion because hunting “Fixed prosthesis with bridges and crowns including and cutting tools are available and fire allows to pre- implants” (p<0.039). process meals. The masticatory performance diminishes with age 4. DISCUSSION [19,28]. In particular, the length of the masticatory sequence required to produce the same particle The chewing surface morphology is admirably size increases. Peyron et al. [28] quantified this adapted to the food of each species [1,4,8]. increase of the required time for chewing with three Individuals with compromised occlusion have an masticatory cycles per ten years of life on average. impaired chewing efficiency compared to those Consequently, a 50% increase in numbers of chewing with satisfactory occlusion [2,10,37]. Categorizing cycles needed to reach the same size of the particles occlusion into four groups-distinct occlusal struc- between 25years and 75years [28]. These data can, tures; reduced occlusal structures; significantly to a certain extent, be transferred to the result of a reduces occlusal structures; no occlusal structures chewing test based on fragmentation procedures. - and correlating these groups with the masticatory As the masticatory sequences are always the same performance reveals the significant impact of length of 30 seconds, the number of chewed parti- occlusal morphology on masticatory efficiency cles decreases with age. (Fig.1a). These results support the influence of Coincidentally, the mean particle size of chewed occlusion on the function of mastication and the particles increases with age. The results show a conti- chewing efficiency. A well-formed and distinctly nuous decrease in number of particles produced shaped occlusal morphology significantly increases by elderly (Fig. 4). The decrease in 10 years can be masticatory efficiency. calculated with approximately 15%. Undoubtedly, The angle’s classification is usually applied to the decrease in masticatory performance is no describe occlusion. And, although critical and longer linear from the age of about 50 years. A possi- noncoherent, the Angle classification is often used to ble explanation for this finding is a progressively deduce functional conditions. In addition, the terms intraoral alteration – including an increasing number norm-occlusion and malocclusion are often used of missing teeth, more and extended dentures and equated to functional or dysfunctional occlusion. reduced structures of occlusal surfaces. The decline 204 Stoma Edu J. 2020;7(3): 197-207 pISSN 2360-2406; eISSN 2502-0285 The influence of occlusion on masticatory efficiency www.stomaeduj.com in the masticatory performance with age follows a particles denote insufficient masticatory perfor- Original Articles similar path for both genders (Fig. 5). Gender-specific mance. The golden standard for testing chewing differences are described in the literature [16,18,32]. performance is the sieve technique. But, the clinical Forces during chewing are higher in males than efforts in performing a chewing test based on females. The masticatory movements of men are the sieving method exceed the resources in daily also executed with greater vertical and transverse practice. Therefore, contemporary IT-technologies amplitude [6,12,13,14]. The overall results confirm including optical methods may be implemented the difference in masticatory efficiency between in clinical routine, as such techniques have been men and women that is quoted in the literature. But, demonstrated to be reliable and accurate to analyse as the difference is similar for soft and hard SCTU, chewing fragmentation test procedures comparably it cannot be inferred that males are much more with sieving methods. Within the limitations of this effective in chewing the hard SCTU than females. study, it can be concluded: This result only partly confirms the fundamental • The quality of occlusion has a significant impact of assumption that, because of higher physical force, chewing efficiency. The masticatory performance males are better able to masticate than women. depends on the natural and/or artificial chewing The clinical occlusal appearance is often used as surface morphology. treatment indicator. The subjective assessment • Angle classification explains chewing efficiency of treatment needs and an objective measure of only to some extent. A reasoning of an individual masticatory performance should coincide. This functional status just from Angle´s classification is required the researchers to make a subjective assess- critical. ment of treatment need without using further tests • Age is an important intrinsic factor which or other data. The assessment was made in the influences masticatory performance. But, at least following categories: clear indication for treatment; in the age groups above 60 years, the intraoral average treatment indication; minor treatment status seems to overrule the influence of age. The indication; no treatment indication. The post hoc maintenance of a sufficient functional oral status is analysis showed that the objective masticatory a crucial task in care of the aging population. efficiency coincides with the assessment of treatment • Gender differences in chewing outcomes, as need for the extreme categories “no treatment described in the literature, can be confirmed indication” and “clear indication for treatment” by the results of this study. It can be added that only, while no significant difference (p=0.515) was the quality of occlusion affects both genders in a found between the “average” and “minor” treatment similar way. Higher muscle forces in males are not indication groups. Therefore, the purely subjective able to compensate poor occlusal quality. assessment of treatment need cannot be considered • The assessment of treatment needs by the clinician to be adequate in individual decision making. based on a clinical inspection correlates with the The aim of oral rehabilitation is to maintain and masticatory performance in clear conditions only restore all functions of the masticatory organ. A clear – either no treatment needs or clear indication for relationship between intraoral status and masti- treatment. If the judgement of the treatment needs catory efficiency can be deduced by the scientific is unclear – minor or average treatment indications literature [2,10,11,19,25,27,32]. It is still unclear what – the chewing efficiency is not correlated. prosthetic rehabilitation best restores the individual’s • Fixed prosthodontics, including implant supp- masticatory function. orted construction, do not reach the chewing The masticatory performance is often debriefed only performance of natural occlusion with minor via questionnaires and self-reporting by patient. restorations. The question arises if prosthetic rehabilitation can CONFLICT OF INTEREST reach the chewing efficiency of natural occlusion? In this particular analysis, only natural occlusion There is a conflict of interest: The author is Founder and CEO of and fixed prosthodontics are included. Based on the OREHAB-Minds GmbH, DE-70567 Stuttgart, Germany. analysed tests of the SCT, it can be concluded, that fixed prosthodontic rehabilitation are not capable to AUTHOR CONTRIBUTIONS reach the functional efficiency of natural occlusion. GS contributed to the concept, protocol, data gathering and 5. CONCLUSION analysis, their interpretation and critically revising the manuscript. The better the masticatory performance, the more ACKNOWLEDGMENTS particles will be found in the lower size ranges. Conversely, it can be concluded that few and large None. Stoma Edu J. 2020;7(3): 197-207 pISSN 2360-2406; eISSN 2502-0285 205 Slavicek G. www.stomaeduj.com REFERENCES Original Articles 1. Lucas PW, Luke DA. Chewing it over: basic principles of food activity of masticatory muscles in women with osteoporosis. breakdown. In: Chivers DJ, Wood BA, Bilsborough A. (eds) Food Braz Dent J. 2009;20(3):237-342. doi:10.1590/s0103- acquisition and processing in primates. Boston, MA: Springer Since; 64402009000300012. 1984. https://doi.org/10.1007/978-1-4757-5244-1_12 [Full text links] [Crossref ] [PubMed] Google Scholar Scopus Google Scholar 21. Woda A, Foster K, Mishellany A, Peyron MA. Adaptation 2. Slavicek G. Human mastication. 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Electromyographic [Crossref ] Google Scholar 206 Stoma Edu J. 2020;7(3): 197-207 pISSN 2360-2406; eISSN 2502-0285 The influence of occlusion on masticatory efficiency www.stomaeduj.com Original Articles Gregor SLAVICEK MD, DDS, M.Sc. CEO, Professor & Director Steinbeis Transfer Institute Biomedical Interdisciplinary Dentistry, Steinbeis University Berlin, Filderhauptstraße 142, 70599 Stuttgart CV Dr. Slavicek is an MD, specialized in Dentistry. He is currently Director of the Steinbeis Transfer Institute Biomedical Interdisciplinary Dentistry, Steinbeis University Berlin. Since 2019, he has been CEO of Orehab Minds GmbH in Stuttgart, Germany. He graduated from the University Vienna (medicine and dentistry), also specializing in Clinical Research at the same university (Master of Science). He attended additional postgraduate orthodontic training at University Aarhus (Denmark), Prof. B. Melsen, and postgraduate gnathological training at University of Florida (USA), Prof. H. Lundeen and Prof. C. Gibbs. He is an honorary member of the Italian Gnathological Society. He received an honorary professorship from the Ukrainian Dental Society. He is an honorary member of the Italian Gnathological Society. He was visiting professor at the first medical state University in Moscow Sechenov (2014-2018). Questions 1. Which of the following statement is incorrect? qa. Chewing efficiency is related to angle classification only to a certain extent; qb. Chewing efficiency increases with age; qc. Chewing efficiency with males and females is significantly different; qd. Chewing efficiency is dependent on the prosthetic rehabilitation. 2. Which of the following parameters can influence chewing efficiency? qa. Chewing surface morphology; qb. Gender; qc. Age; qd. Answers 1-3 are correct. 3. A subjective assessment of treatment needs by the clinician? qa. Can be considered as a sufficient method to understand individual masticatory functions; qb. Is able to distinguish even small differences in treatment needs; qc. Is not possible to distinguish even in extreme situations of treatments needs (not treatment indication vs. clear treatment indication); qd. A subjective assessment should be proven by suitable tests. 4. An adequate chewing function test for clinical use? qa. Is based on the principles of the sieving method; qb. Considers the ability of the stomatognathic system to fragment food; qc. Contemporary IT-supported methods based on the evaluation of standardized photos are qualitatively equivalent to the sieving method; qd. Answers 1-3 are correct. Stoma Edu J. 2020;7(3): 197-207 pISSN 2360-2406; eISSN 2502-0285 207