Article_7_3_6
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.
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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].
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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
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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).
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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
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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
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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
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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
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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
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206 Stoma Edu J. 2020;7(3): 197-207 pISSN 2360-2406; eISSN 2502-0285
The influence of occlusion on masticatory efficiency
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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.
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