• Long axis tilts buccally when viewed from the front.
• Long axis is tilted distally when viewed from the side.
• Only the mesiopalatal cusp contacts the horizontal plane.
• Long axis tilts buccally more steeply than the first molar when
• Long axis tilts distally more steeply than the first molar when
• All the four cusps are short from the horizontal plane but the
mesiopalatal cusp is more close to it.
Mandibular posterior teeth (fig. 7-18)
• Long axis tilts slightly lingually when viewed from the front.
• Long axis is parallel to the vertical axis when viewed from the front.
• Lingual cusp is closer to the horizontal plane than the buccal cusp
which is 2 mm above the plane.
FIGURE 7-18 Arrangement of the mandibular posterior teeth
in relation to the maxillary teeth.
• Long axis tilts slightly lingually when viewed from the front.
• Long axis is parallel to the vertical plane when viewed from the
• Both buccal and lingual cusps are 2 mm above the horizontal plane.
• Long axis tilts slightly lingually when viewed from the front.
• Long axis tilts slightly mesially when viewed from the side.
• All the four cusps are above the horizontal plane with the buccal
and distal cusps being higher than the mesial and lingual cusps.
• Long axis of the tooth tilts lingually, slightly more than the first
molar when viewed from the front.
• Long axis of the tooth tilts mesially, slightly more than the first
molar when viewed from the side.
• All the cusps are above the horizontal plane and higher than the
first molar; also, the buccal and distal cusps are higher than the
Modiolus is defined as ‘the area near the corner of the mouth where eight
muscles converge that functionally separates the labial vestibule from the
buccal vestibule’. (GPT 8th Ed)
Modiolus is the meeting place of eight muscles, which forms a
distinct conical prominence at the corner of the mouth. The word
modiolus is derived from Latin and means ‘hub of wheel’ (Fig. 7-19).
FIGURE 7-19 Modiolus is a muscular knot which is formed
Following are the muscles meeting at the modiolus:
(ii) Quadratus labii superioris
(iii) Caninus (levator anguli oris)
(v) Quadratus labii inferioris
(vi) Triangularis (depressor anguli oris)
All these muscles merge into the orbicularis oris which determines
• Modiolus becomes fixed when the buccinators contract while
• Contraction of the modiolus presses the corner of the mouth against
the premolars such that the occlusal table is closed in the front.
• Because of this action, food cannot escape out of the mouth when
crushed by the premolars and the molars.
• It contributes to denture stability.
Phonetics is defined as ‘the movement and placement during speech of the
organs that serve to interrupt or modify the voiced or unvoiced air stream
into meaningful sounds’ or ‘the study of speech sounds, their production,
combination and their representation by written symbols’.
Speech is divided into six components as follows:
Respiration: During speech, the inhalation phase is shortened and the
exhalation phase is prolonged.
Phonation: Speech requires multitude of positions, varying tension,
vibratory cycles and intricate coordination of the vocal folds with
Resonation: The pharynx, the oral cavity and the nasal cavity act as
resonating chamber by amplifying some frequencies and muting
others, thus refining tonal quality.
Articulation: The velopharyngeal mechanism proportions the sound
and/or air stream between the oral and nasal cavities and influences
voice quality (or the basic sound) that is perceived by the listener.
• Amplified, resonated sound is formulated into
meaningful speech by the articulators, namely, the
lips, tongue, cheeks, teeth and palate.
Neurological integration: Speech is integrated by the central nervous
system both at the peripheral and central levels.
Audition or the ability to receive acoustic signals is
• The successful performance of these functions is
necessary for the production of acceptable speech.
• All speech sounds are made by controlling air.
Classification of Speech Sounds
(i) Labial sounds (e.g. b, p, m)
(ii) Labiodental sounds (e.g. f and v)
(iii) Dental and alveolar sounds (e.g. th, t, d, n, s, and z)
(iv) Palatal sounds (e.g. year, vision, onion)
(v) Velar (posterior sounds, e.g. k, g, ng)
Role of phonetics in complete denture patient
Denture thickness and peripheral Outline
• Unduly thick denture bases cause incorrect phonation and loss of tone
due to decrease of air volume and loss of tongue room in the oral
• The production of the palatolingual group of sounds involves contact
between the tongue, and the palate, the alveolar process or the
• With the consonants ‘T’ and ‘D’, the tongue makes firm contact with
the anterior part of the hard palate, and is suddenly drawn
downwards, producing an explosive sound; any thickening of the
denture base in this region may cause incorrect formation of these
• When producing the ‘S’, ‘G’ (soft), ‘Z’, ‘R’ and ‘L’ consonants sounds,
contact occurs between the tongue and the most anterior part of the
hard palate, including the lingual surfaces of the upper and lower
• In case of the ‘S’, ‘C’ (soft) and ‘Z’ sounds, a slit-like channel is formed
between the tongue and palate through which the air hisses.
• If the artificial rugae are overpronounced, or the denture base is too
thick in this area, the air channel will be obstructed and a noticeable
• To produce the ‘Ch’ as in church and ‘J’ as in judge sounds, the
tongue is pressed against a larger area of the hard palate, and in
addition makes contact with the upper alveolar process, bringing
about the explosive effect by rapidly breaking the seal thus formed.
• The ‘Sh’ sound is similar in formation, but the air is allowed to
escape between the tongue and palate without any explosive effect,
and if the palate is too thick in the rugae region, it may impair the
production of these consonants.
• The formation of the labial sounds such as ‘P’, ‘B’ and ‘M’ are made
• With ‘P’ and ‘B’ sounds, the air pressure is built behind the lips and
released with or without voice sounds, whereas in ‘M’ sound, lip
• For this reason, ‘M’ sound can be used as an aid in obtaining the
correct vertical dimension because a strained appearance during lip
contact, or the inability to make contact, indicates that the bite
blocks are occluding prematurely.
• With the production of ‘Ch’ (soft), ‘S’ and ‘J’ sounds, the teeth come
very close together, if the vertical dimension is excessive, the
dentures will actually make contact as these consonants are formed,
and the patient will most likely complain of ‘clicking teeth’.
• If the distance is too large, then the vertical dimension established is
• The labiodentals, ‘F’ and ‘V’, are made between the upper incisors
and the labiolingual centre to the posterior one-third of the lower
• If the occlusal plane is set too high, the ‘v’ sound will be more like
• If on the other hand, the plane is too low, the ‘f’ sound will be more
• The incisal edges of the central incisors contact the lower lips in a
proper position as the patient says ‘fifty-five’.
Anteroposterior position of the incisors
• Anteroposterior positioning of the teeth is very critical in the
• Anteroposterior position of the anterior teeth and thickness of the
labial flange can affect the sounds of ‘b’ and ‘p’.
• In setting the upper anterior teeth, consideration of their labiopalatal
positions is necessary for the correct formation of the labiodental
sounds such as ‘F’, ‘V’ and ‘Ph’.
• If they are placed too far palatally, they will contact the lingual side
of the lower lip when ‘f’ and ‘v’ sounds are made.
• During making of dental sounds such as ‘th’, ‘this’, ‘that’, if 3 mm of
the tip of the tongue between the upper and lower incisors is not
visible, then anterior teeth are placed too far forward.
• Alveolar sounds such as ‘t’, ‘d’, ‘n’, ‘s’ and ‘z’ are produced when
the tip of the tongue contacts the anterior part of the palate or the
lingual side of the anterior teeth.
• If teeth are placed too far lingually, ‘t’ will sound as ‘d’.
• Similarly, if the anterior teeth are set too far anteriorly, ‘d’ will
• ‘S’ sound is made when the tip of the tongue contacts the alveolus in
the area of the rugae with the small space for the escape of air
between the tongue and the alveolus.
• The size and shape of this small space determine the sound quality.
• If the space is broad and thin, the ‘s’ sound will develop as ‘sh’.
• If the space is too small, a kind of whistle will result.
• Errors of construction in this region involve the vowels ‘I’ and ‘E’
and the palatolingual consonants ‘K’, ‘NG’, ‘G’ and ‘C’ (hard).
• In the latter group, the air blast is checked by the base of the tongue
being raised upward and backward to make contact with the soft
• A denture which has a thick base in the postdam area, or that edge
is finished square instead of tapering, will probably irritate the
dorsum of the tongue, impeding speech.
• Indirectly the postdam seal influences phonation, for if it is
inadequate the denture may become unseated during the formation
of those sounds having an explosive effect, requiring the sudden
repositioning of the tongue to control and stabilize the denture.
• If the teeth are set to an arch which is too narrow, the tongue will be
cramped, thereby, affecting the size and shape of the air channel.
• This results in faulty phonation of consonants such as ‘T’, ‘D’, ‘S’,
‘M’, ‘N’, ‘K’, ‘C’ and ‘H’, where the lateral margins of the tongue
make contact with the palatal surfaces of the upper posterior teeth.
• Therefore, it is important to place the lingual and palatal surfaces of
the artificial teeth in the position previously occupied by the natural
• Speech problems are usually identified immediately after prosthetic
• Speech adaptation to new complete dentures normally takes place
within 2–4 weeks after insertion.
• If maladaptation persists, special measures should be taken by the
dentist or by a speech pathologist.
• When new prostheses are to be made for these patients, certain
difficulties in learning new motor acts may delay and obstruct the
• Consequently, a virtual duplication of the previous denture’s arch
form and polished surfaces, especially the palate of the maxillary
denture, will ensure a minimal period of postinsertion speech
• Old dentures may be of guidance when designing new ones and, if
necessary, a virtual copy of the denture could be made.
• This procedure will frequently solve problems that may arise due to
speech and adaptation difficulties.
Characterization is defined as ‘to alter by application of unique markings,
indentations, colouration and similar custom means of delineation on a tooth
or dental prosthesis thus enhancing natural appearance’. (GPT 8th Ed)
• R.E. Lombardi (1973) stated that arrangement of central incisors
reflected the patient’s age, lateral incisor reflected the patient’s sex
and the canine’s reflected the patient’s vigour or personality.
• Frush JP and Fischer RD (1958) advocated that dentogenics
influences tooth arrangement, shade and teeth selection.
• Teeth can be characterized to enhance aesthetics by crowding or
tilting the mandibular anterior teeth.
• The best guide to characterize denture is an old photograph or old
cast of the patient with natural teeth.
Characterization of the denture base
• Aesthetics of the denture base has direct influence on the facial
• Frush and Fisher (1957) recommended convex, round and shortened
• They also advocated exposure of more of the cervical root portions
of the denture teeth in older patients.
• Finer stippling along the lighter base shade was recommended for
women, whereas heavy stippling with rougher base shade was
• Interdental papilla and the muscle attachment areas are preferred
with deeper shades of red to enhance aesthetics.
• To characterize the denture base correct festooning, careful stippling
and custom staining are recommended.
• Various shade guides for denture base materials are available or can
• E. Pound and S.C. Choudhary suggested the use of diagram to map
out areas to be stained with different shades of colour.
• R.M. Morrow (1986) recommended use of five shades in different
(i) Basic pink is used over hard tissue such as attached
(ii) Light red is used for papilla and muscle
(iii) Medium red is used sparingly.
(iv) Purple is used sparingly in heavily pigmented
(v) Brown is used for heavily pigmented gingiva.
• Space of Donders is the space that lies above the dorsum of the
tongue and below the hard and soft palates when the mandible and
tongue are in the rest position.
• Silverman’s speaking space is the space that occurs between the
incisal and/or occlusal surfaces of the maxillary and mandibular
• For most of the patients, the average speaking space is 1.5–3 mm.
• Patients with class II occlusion have larger speaking space, i.e. 3–6
• Patients with class III occlusion have reduced speaking space, i.e.
• Palatogram is the graphic record of the area of the palate contacted
• Size of the artificial teeth is determined by the size of the face,
interarch space, length of lips, skeletal jaw relation, amount of
resorption and size of the anterior arch from cuspid-to-cuspid.
Evolution of Anatomic and Semi-Anatomic Teeth, 149
Evolution in the Development of Anatomic and
Evolution of Nonanatomic Teeth, 150
Evolution in the Development of Nonanatomic
Complete Denture Occlusion, 151
Basic Requirements for Complete Denture
Lingualized Occlusion Concept, 152
Neutrocentric Occlusion or Monoplane Occlusal Scheme, 154
Requirements for Balanced Occlusion, 156
Unilateral Occlusal Balance, 156
Bilateral Occlusal Balance, 156
Protrusive Occlusal Balance, 157
Concepts of Balanced Occlusion, 157
Occlusion in complete dentures involves the contact between the
occlusal surfaces of the teeth in both static and functional movements.
These contacts have definitive role in the stability, chewing efficiency,
comfort and aesthetics of the dentures.
Occlusion is defined as ‘the static relationship between the incising or
masticating surfaces of the maxillary or mandibular teeth or tooth analogues’.
Articulation is defined as ‘the static and dynamic contact relationship
between the occlusal surfaces of the teeth during function’. (GPT 8th Ed)
Balanced articulation is defined as ‘a continuous sliding contact of
upper and lower cusps all around the dental arches during all closed grinding
movements of the mandible’. (GPT 8th Ed)
The differences between natural and artificial occlusions are given
DIFFERENCES BETWEEN NATURAL OCCLUSION AND
Natural Occlusion Artificial Occlusion
Natural teeth function independently of each other and each
tooth disperses the occlusal load
Artificial teeth function as a unit and occlusal
load is dispersed over the entire unit
Nonvertical forces are well tolerated and affect only the teeth
Lateral or nonvertical forces affect all the
teeth on the base and can traumatize the
Second molar is the favoured area for heavy mastication for
Heavy mastication over the second molar can
shift or tilt the denture base, if they are on
Bilateral balance is not necessary and may cause hindrance in
Bilateral balance is necessary, as it increases
Malocclusion can be uneventful for a long time Malocclusion poses immediate problems
involving all the teeth and the base
Proprioceptive impulses give a feedback mechanism to No such mechanism exists in denture patient;
avoid the occlusal prematurities; it can help the patient to
any occlusal prematurity can destabilize the
Natural teeth are retained by the periodontal ligaments which
are uniquely innervated and structured
The denture rests on the moist and slippery
Evolution of anatomic and semianatomic teeth
Evolution in the development of anatomic and
1914: Dr Alfred Gysi is credited for designing the first anatomic
porcelain tooth with 33° cusp angle. These teeth were called
‘trubyte’, which had transverse ridges for providing occlusion with
1922: Victor Sears designed a ‘channel tooth’. In this, deep channels
were created in the maxillary occlusal surface mesiodistally which
ran through the entire length of all the four posterior teeth. The
lower posterior teeth were reduced to almost half the buccolingual
width of the anatomic tooth. The teeth were almost a single central
ridge which contacted the maxillary channel teeth to provide an
unlimited protrusive glide (Fig. 8-1).
1927: Gysi introduced a modified ‘crossbite’ posterior teeth. In his
modification, the maxillary buccal cusp was almost eliminated
resulting in a prominent lingual cusp occluding into the lower
anatomic tooth. He described the modification as ‘mortar and pestle’
action of this occlusal scheme.
1930: Avery Brothers introduced ‘scissor-bite tooth’. The posterior teeth
were modified anteroposteriorly by grinding steps on the surface of
the teeth. The angle of these steps was modified by the condylar
inclination. The modified occlusal surfaces were meant to shear the
food in lateral excursions (Fig. 8-2).
1932: Pilkington and Turner developed anatomic posterior tooth with
slightly shallower cusp angle of 30°. Their tooth was called
1935: F.H. French and Universal Dental Company developed a modified
posterior tooth. The maxillary tooth had a central groove running
mesiodistally with shallow buccolingual inclines to reduce the
1936: H.F. McGrane marketed ‘curved cusp posterior tooth’. These teeth
were designed to lock anteroposteriorly and be free laterally. These
were intended to shear food in harmony with the lateral condylar
guidance determined by Bennett angle.
1937: Max Pleasure proposed the occlusal scheme which modified the
position of the lower posterior teeth more buccally. This enables the
forces to be directed lingually, favouring the stability of the lower
1941: Sir Howard Payne introduced the concept of lingualized occlusion.
1942: John Vincent used metal inserts in the resin posterior teeth. The
metal inserts protruded from the middle third of the posterior
occlusal surfaces with shallow buccal and lingual cusps protruding
beyond the metal inserts. These teeth opposed the French
mandibular posteriors. With wear of the teeth, the heaviest chewing
forces were concentrated in the centre of the denture to minimize
1957: Myerson FLX ‘freedom in lateral excursion’ posteriors when
properly arranged resulted in balanced occlusal contacts.
1961: M.B. Sosin replaced the maxillary second bicuspid and first and
second molars with cleat-shaped vitallium forms called cross blades.
The patient was made to chew wax in the lower. The indentation
was converted into gold and was cured with the denture (Fig. 8-3).
1977: B. Levin modified cross blade teeth in the upper row by reducing
FIGURE 8-1 Sear’s channel type posterior teeth.
FIGURE 8-2 Avery Brother’s scissor-bite teeth.
FIGURE 8-3 Sosin’s cross blade posterior teeth.
Evolution of nonanatomic teeth
Evolution in the development of nonanatomic
1929: R.Hall was the first to introduce nonanatomic teeth. He called it as
‘inverted cusp tooth’. This design has flat occlusal surface with sharp
concentric ridges which provided efficient shredding of the food.
The only drawback was that the food was clogged into the
depressions as no escape ways were provided.
1929: R.L. Myerson designed a cuspless tooth and called it ‘true cusp’. It
has series of transverse buccal lingual ridges with sluiceways
1934: Nelson designed nonanatomic teeth and called them ‘chopping
block’. The ridges on the mandibular teeth ran transversely and on
the maxillary teeth ran mesiodistally. This provided an efficient
chopping and shredding of food (Fig. 8-4).
1939: M.G. Swenson designed posterior tooth called ‘nonlock’. These
were flat teeth with sluiceways for efficient shredding and clearing
of food from the occlusal table.
1946: I.R. Hardy developed nonanatomic teeth with metal inserts in
upper and lower teeth with vitallium occlusal. Narrow zigzag
vitallium ribbon was inserted on the occlusal surfaces running
mesiodistally. This established a narrow, flat, convoluted metal
surface that was slightly higher than the encapsulating resin. This
metal-to-metal contact provided efficient cutting ability (Fig. 8-5).
1951: Myerson Tooth Corporation introduced the first cross-linked
acrylic tooth in a flat occlusal scheme and called it ‘shear–cusp tooth’.
These teeth were of higher wear-resistant quality.
1952: W.A. Cook introduced Coe masticators. In this, the second
premolar and the first molar had flat stainless steel casting with the
holes on the occlusal surfaces that opened to a port on the buccal
surface. However, food used to clog these ports and was very
difficult for the wearer to clean it.
1957: W. Bader designed a ‘cutter bar’ scheme. In this scheme, the upper
porcelain cuspless teeth were opposed by metal cutting bar
replacing second premolar, first molar and second molar.
1967: J.P. Frush advocated a scheme called ‘linear occlusal concept’. The
flat maxillary ridge opposed the flat lower ridge with a single
FIGURE 8-4 Nelson’s chopping blocks.
FIGURE 8-5 Hardy’s vitallium occlusal teeth.
The term occlusion is referred to describe static contacts of the teeth
that exist after the jaw movement has stopped and the tooth contacts
V.H. Sears (1952) has laid down the following guidelines to plan
• Smaller the occlusal surface, lesser will be the force transmitted to
• Vertical forces applied to the inclined occlusal plane result in
nonvertical forces on the denture base.
• Vertical forces applied to the inclined supporting tissues result in
nonvertical forces on the denture base.
• Vertical forces placed outside the crest of the ridge cause tipping of
• Vertical forces on the denture base resting on the flabby tissues
produce leverage forces resulting in instability of the denture.
Basic requirements for complete denture
• It should provide stability of occlusion in the centric and eccentric
• It should provide bilateral balanced occlusal contact in all eccentric
• It should provide freedom in movement of the cusp mesiodistally to
allow for gradual settling of denture on ridge resorption.
• Buccolingual cuspal height should be decreased to reduce the
horizontal forces on the dentures.
• It should have efficient cutting, penetrating and shearing occlusal
• It should provide functional lever balance.
• It should have sharp ridges or cusps and sluiceways for increased
• It should provide anterior incisal clearance during posterior contact
functions such as mastication and bruxism.
These basic requirements can be fulfilled, if any occlusal scheme is
divided into the following units:
Requirements for incising units
• Incising units should be sharp to enhance the cutting efficiency.
• These should be out of contact during mastication.
• These should have as shallow or flat incisal guidance as possible for
• These should have adequate overjet to permit denture base settling.
• These should contact during protrusion.
Requirements for working units
• Working units should enhance the cutting and grinding efficiency.
• These should have reduced buccolingual width to decrease the
forces transmitted to the supporting tissues.
• These should contact simultaneously during chewing and eccentric
• These should be positioned over the crest of the ridge for better
• These should transmit the forces vertically to the supporting
• These should centre the occlusal load to the anteroposterior centre
• These should have occlusal plane parallel to the mean foundation
Requirements for balancing units
• Balancing units should contact the second molar during protrusion.
• These should contact along with the working side at the end of the
• These should provide smooth gliding contacts during lateral and
Different occlusal concepts in complete dentures are:
• Bilateral balanced occlusion
• Monoplane/neutrocentric occlusion
• Physiologically generated occlusion
This is defined as ‘this form of denture occlusion articulates the maxillary
lingual cusps with the mandibular occlusion surfaces in centric working and
nonworking mandibular positions’. (GPT 8th Ed)
• A. Gysi was the first to report the biomechanical advantages of
lingualized tooth forms in 1927.
• Gysi designed and patented ‘crossbite posterior teeth’ in 1927.
• Lingualized occlusion concept was first described by Sir Howard Payne
• E. Pound and G.R. Murrell (1973) also advocated this concept of
• Earl Pound coined the term lingualized occlusion (1970).
• It is an attempt to maintain the aesthetic and food penetration
advantages of the anatomic form while maintaining the mechanical
freedom of the nonanatomic form.
• This concept utilizes anatomic teeth for the maxillary denture and
modified nonanatomic or semi-anatomic teeth for the mandibular
• Anatomic posterior teeth with prominent lingual cusp are used for
• Nonanatomic or semi-anatomic teeth are used for mandibular
• Maxillary lingual cusps should only contact in centric position (Fig.
• Maxillary buccal cusp was not allowed to contact the mandibular
teeth in centric or eccentric positions.
• Balancing and working contacts only at upper lingual cusps (Fig. 8-
FIGURE 8-6 Lingualized occlusion in centric position.
FIGURE 8-7 Lingualized occlusion with balancing and
• It is helpful when the patient places high priority on aesthetics but a
nonanatomic occlusal scheme is indicated by severe alveolar
• It is indicated for class II jaw relationship or displaceable supporting
• It is indicated in the cases where complete denture opposes a
• It is indicated for patients with flabby ridge coverings.
• It provides cross-arch balance.
• It improves denture stability.
• It decreases lateral contact because maxillary lingual cusps provide
sole contact with mandibular posterior teeth.
• It minimizes the damaging lateral forces.
• Bilateral balance can be obtained.
• Adjustments can be done easily.
• It can be used in class II and class III jaw relationships.
• Upper teeth maintain aesthetics.
• Vertical forces are centralized on the mandibular teeth, resulting in
increased stability of the denture and maintenance of the
supporting hard and soft tissues.
• It is less natural than the cusp tip to fossa occlusion.
• It results in decreased masticatory efficiency as maxillary buccal
cusp does not contact the mandibular teeth.
Neutrocentric occlusion or monoplane
• This concept maintains that the ‘anteroposterior plane of occlusion
should be parallel with the plane of the denture foundation and not dictated
by the horizontal condylar guidances’.
• M.M. DeVan gave the concept of neutrocentric occlusion in 1955.
• This concept of occlusion eliminates any anteroposterior or
mediolateral inclines of the teeth and directs the forces of occlusion
to the posterior teeth (Fig. 8-8).
• When teeth are arranged on the plane, these are not inclined to form
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