Teeth SelectionThe next step in the Fabrication of a complete denture after

articulation is teeth arrangement. Before arrangement, the teeth should be selected, Artificial teeth are available in various forms and shades. Teeth selection is very important as the selection of the appropriate size, shape/occlusal form and colour/shade of the artificial teeth determines the aesthetics and the function of the denture. Aesthetics is a pleasurable feeling created within an individual against the perception of an object.

Objectives in Teeth Selection The teeth should be in harmony with the surrounding

tissues. They should maintain the vertical dimension They should be efficient for mastication. Posterior teeth should be selected based on function

whereas the anterior teeth are selected predominantly based on aesthetics.

General Considerations in Teeth SelectionThe following principles should he considered prior to

teeth selection: The patient should be seated upright with his facial

muscles relaxed. The operator should sit in front of the patient and adequate

lighting should be used. Light source can be daylight, neon light or fluore-scent light.

The selection of artificial teeth for a complete denture can be divided into two sections:

Anterior teeth selection Posterior teeth w4vcfion

ANTERMTEETH SELECTIONAnterior teeth play an important role in the aesthetics of a

patient. They am not subjected W heavy occlusal load like the posteriors. Hence, aesthetics is given more importance during

anterior teeth selection. The following factors are also considered during the selection of anterior teeth:

Size of the teeth Form of the teeth Colour/shade of the teeth

Size of the Anterior TeethThe tooth Size should be appropriate to the size of the face

and sex of the patient, The following methods are used as a guide to select the size of the teeth:

Methods using pre-extraction records. Methods using anthropological measurements of the

patient. Methods using anatomical landmarks. Methods using theoretical concepts. Other factors.

Methods Using Pre-extraction Records The pre-extraction records like diagnostic casts,

photographs radiographs teeth of close relatives and preserved extracted teeth can be used to determine the size of the artificial teeth.

Diagnostic casts They are prepared before the extraction of the teeth. The operator can obtain an idea about the size and shape of the teeth from these casts. The actual Size and shape required can be determined brut the shade of the teeth cannot be determined using this method.

Pro-extraction photographs Photographs showing the lateral, anterior and anterolateral views of the patient should ken before extraction. These photographs must show at least the incisal edges of the anterior teeth, This method is useful to determine the exact width and outline of the teeth.

Pro-extraction radiographs This is usually obtained from the patient's previous dentist. Radiographic errors are a major limitation to this method. The occluso-gingival height and the outline of the teeth can be recorded. But the con-tour and size cannot be accurately determined, bemuse the radiograph is a

two-dimensional image.Teeth of close relatives This method is usually followed

only if the other records are not available, The size and contour of the patient's son or daughter's tooth is taken as reference.

Preserved extracted teeth This is the best method to determine the size of the anterior tooth. The exact details about the size and contour can be recorded from this method.

Methods using Anthropological Measurements of the PatientAnthropological measurements am mushy post-extraction

records, made directly from the Edentulous patient, These methods measure certain anatomical dimensions and derive the size of the teeth using certain formulae.

Anthropometric cephalic index The transverse circumference of the head is measured using a measuring tape at the level of the forehead. The width of the upper central incisor can be derived from this measurement. Sears called this formula as the anthropometric cephalic index.

witch of the upper controlincisor=Circumference of thehead13

The bizygomatic width can be used to deter-mine the width of the central incisor and also the combined width of the anteriors. The bizygomatic width is the distance measured between the malar prominences on either side. This measurement is also used in Berry's Biometric index and H. Pound's formulae.

معادلة

Berry's Biometric index Berry's bimetric index is used to derive the width of the central incisor using the bizygornatic width and/or the length of the face. the formula using the length of the face cannot be used for edentulous patients. The length of the face is the distance measured between the hairline and the tip of the, chin.معادلة

Based on the size of Me lace This is a tentative measurement in which the size, of the teeth is determined by the size of the face. For example, large teeth are selected for patients with a large face.

H. Pound's formula Pound derived two formulae to determine the width and length of the central incisor using the bi-zygomalic width and the length of the face respectively.

معادلة

Based on the width of the nose The width of the nose is measured with a venire caliper. This measurement is transferred to the occlusal rim. The width of the nose, is equal to the combined width of the anterior teeth.

Methods using Arrafomcal LandmarksVarious anatomical landmarks like the size of the

maxillary arch and location of the canine eminences, buccal frenal attachment, corners of the mouth and sin of the nose can be used to determine the size of the artificial teeth.

Size of the maxillary arch The distance between the incisive papilla and the ha molar notch on one side is added with the distance between two hamular notches. This gives the combined width of all the anterior and paserior teeth of the maxil-lary arch.

Location of canine eminences Acanine eminence is formed in the region between the canine and the first premolar after extraction of teeth.The distance between the two canine eminences is measured along the residual ridge. This measured value gives the combined width of the anterior teeth .

Location of the buccal franal attachments The attachments of tire buccal frenum are marked on the residual ridge. The distance between the two markings recorded along the residual ridge gives the combined width of the maxillary anteriors.

Location of the corners of the mouth The comer of the mouth marks the distal end of the canine. The comers of the mouth are recorded on the occlusal rim and the distance is measured between these markings. The anterior teeth are set within these markings.

Location of the alt of the nose The patient is asked to sit upright and look straight. A line pas- sing through the midpoint between the eyebrows and the lateral end of the alt of the nose extended onto the occlusal rim gives the combined width of the anterior teeth .

Methods Using Theoretical ConceptsThe following theoretical concepts proposed by various

authors can be used Codetermine the size of the anterior teeth.Winkler's concept According to Winkler, the teeth should

be selected based on three different views, namely, physiological, psychological and bio-mechanical.

Physiological-biological the facial musculature contributes to the aesthetics of a patient. Increasing the thickness of the denture base in the labial and buccal sulci can produce a puffy appearance. Facial wrinkles fade when the vertical dimension is increased. But this should not be carried out to avoid other complications listed in the previous chapter. The dentist should evaluate the perioral tissues and arrange the teeth accordingly. Refer clinical examination in Chapter 2.

Physiological, A patient with a positive self-evaluation shows a broad smileand the one with a negative self-evaluation shows a tight-lipped small smile. The Camper's line is the psychological plane of orientation. It is raised in happy people and is tilted downward in depressed people.

Biomechanical The teeth should be placed such that they fulfil the biomechanics of the denture. It is not-necessary to set the teeth on, outside, or inside the ridge. Instead they should beset in the neutral zone (the zone of balance between the buccal and lingual musculature) .

Typal form theory: Leon Williams (1917) This theory helps to determine the size and form of the anterior teeth.

According to him, the shape of the teeth should be inverse of the shape of the face. That is, if the face tapers downwards, the teeth should taper upwards.

Steins, in 1936, opposed this concept and said that the shale of the will nay warp for each individual, because, it was not possible for two fingerprints to be alike. According tit him, the outline of the teeth are not important. because, it is subjected tit change throughout life. Ile proposed that tile size, colour, form and contour are the most important factors it, be considered during will sedation.

Temperamental theory: Dr. Sparzheim This theory is based on the concept of Hippocrates. It is one of the oldest theories proposed around 2400 Years ago. Hippos rates stated that the body comprised of four mires of ???? namely blood, phlegm, yellow and black Files. Imbalance of these juices is the basis for the various ailments and differen-ces in man.Man can classified based oil the dominance of humour as follows:

Sanguineness type Blood dominance. Phlegmatic type: Phlegm dominance (phlegm

is a oaten' fluid elaborated from brain). Choleric type: Yellow bile dominance (from liver). Melancholic type. Black bile dominance (from spleen).

Association of certain mental, functional and physical characteristics created the tempera-mental theory. People of each group exhibit a certain I vile of teeth.

Concept of Harmony: J. W While in 1872 Accor-ding to him, the size and colour of tile teeth Should be in harmony with the size of the head and colour of the eye, respectively.

Other factors Other factors that influence the size of teeth are:

Size of file face. Inter-arch spacing. Distance between file distal ends of the maxillary

cuspids. Length of the lips. Size n and relation of the arches.

Form of the Anterior TeethThe form or outline the anterior teeth can be determined

using the following factors: Shape of thy patient's face or facial form. Patient's profile. Dentogenic concept and dynesthetics.

Shape of the Patient's Face or Facial FormThis is based on Typal form theory by Leon Williams.

According to him, the facial dorm can be described as one among the following four types:

Ovoid Tapering Square Combination of the above.

The teeth selected should be in harmony with the facial form. Ovoid teeth are preferred for patients with an oval face, etc.

Patient's ProfileThe patient may have a convex, straight or a concave

profile. The labial form of the anterior teeth should be similar to the facial profile of the patient. For example, the labial form should be straight for patients with a straight profile, convex for a patient with a convex profile .

Dentogenic Concept and Dynesthetics. (Sex, Personality. Age or SPA factor)

It was first described by Frush and Fisher. According to them, the sex, personality and age of the patient determine the form of the anterior teeth.

Sex The form or shape of the teeth differs in males and females. The differences in the shape of the anterior teeth in males and females are:

In females, the incisal angles are more rounded and the teeth have a lesser angulation. In males, the incisal angles

are rounded to a lesser degree and the teeth are more angular.

The incisal edge of the central incisors is parallel to the lips and the laterals are above the occlusal plane in males. But the incisal edges of the central and lateral incisors follow the curve of the lower lip in females.

The distal surface of the centrals am, rotated posteriorly for females.

The mesial surface of the lateral incisors am totaled anteriorly in relation to the centrals in females.

In males the mesial end of the laterals am hidden by the centrals. This makes the canine very prominent in males.

Only the mesial thirds of the canines am visible in females because they am rotated anteriorly, whereas even the middle two-thirds of the canines am visible in males.

The cervical regions am prominent in males than in females.

Females on smiling expose mum anterior teeth hence, the premolars should be arranged based on aesthetics for females.Age The age of the patient IS important in teeth selection

because of the physiological and functional changes that occur in the oral tissues. The patient can be either young, middle-aged or old-aged. The following changes are observed with an advance in age of the patient:

Due to decrease in muscle, tone, sagging of the cheeks and the lower lips occur. To prevent cheek biting (due to sagging), the horizontal overlap of the posterior teeth can be increased.

Inter-occlusal distance reduces with age. Hence, mandibular teeth are mom visible than the maxillary teeth.

Old people usually have abraded teeth with worn out contacts. Hence, placement of con-toured teeth may look artificial.

Old patients have gingival recession. It can be reproduced in the dentures to provide a natural appearance.

Old people show a blunt smile line and pathologic migration of teeth.

The colour of the teeth also changes with age. In old people, the enamel is abraded and the dentine which carries a yellow tinge, is more visible (Refer colour selection).Personality The dentist should and arrange the teeth so that

it improves the patient's personality. The patient can be either vigorous or delicate.

More squarish, large teeth are, selected for vigorous people.

The anteriors should be in a flat plane for executives. For executives, the teeth should be relatively smaller and

more symmetrically arranged.

Colour for Anterior TeethBefore selecting the colour for anterior teeth, some basic

concepts about colour should be understood. A single colour can be described under four parameters.

Hue. Saturation or chroma. Brilliance or value. Translucency

HueIt denotes a specific colour produced by a specific

wavelength of light. It should be in harmony with the patient's skin colour or else it will produce an artificial look for the denture.

Saturation or ChromeIt is the amount of colour per unit area of an object. In

other words, it denotes the intensity of the colour. Objects with highly saturated colours lack depth.

Brilliance or ValueIt denotes the lightness or darkness of an object. It is

actually the dilution of the colour with either black or white to

produce darker or y lighter shades respectively. In people with light skin colour, teeth with lighter shades should be chows and vice versa.

TranslucencyIt is the property of the object to partially allow passage of

light through it. Enamel has high brilliance and translucency; hence, artificial teeth should also show the same properties for a natural appearance.

The hue and brilliance of a tooth is influenced or determined by the following factors:

Age. Habits. Complexion. Colour of the eyes. Colour of the patient's hair.

Age Young people have lighter teeth whole the colour of the

pulp is shown through the translucent enamel. Old people show dark and opaque teeth due to the

deposition of secondary dentin and constituent reduction in size of the pulp chamber.

Teeth are, more shier in old people as they getpolished due to regular wear of the teeth.

Teeth of older people obtain brownish tinge because exposed dentin tends to stain.

Preserved extracted teeth are not used to select the colour of the teeth because thee become discoloured (as they are non-vital).

HabitsSmokers, alcoholics and pan chewers have discoloured

teeth due to stains. In such people, porcelain teeth am preferred because they am not porous and do not allow percolation.

Complexion The colour of the firth chosen should be in harmony with

the complexion of the patient, The colour of the face is more important because the teeth fall into the framework of the face.

Colour of the Eyes Only the colour of the iris is considered. This measure is more unreliable because the eyes are too

small and faraway from the teeth to significant influence the choice of colour.

Colour of the Patient's HairIt is very unreliable because of factors like cosmetics, etc.

Also, hair colour changes, with age.Steps in the selection of colour for anterior teeth For the

replacement of a single tooth, the adjacent teeth can be taken as a guide. For an edentulous patient, factors like skin colour, hair colour and eye colour are considered.

The following reference points on the face can be used to select the colour of the troth:

Side of the nose: This point helps to determine the basic title. brilliance and saturation.

Under the lips with only the incisal exposed: This reference point gives an idea of how the teeth will look when the patient is relaxed.

Under the lips with mouth aide open and only the cervical third cervical thinl couered: The third reference point gives an idea of how the teeth will look when the patient is smiling.Squint lost It is used to check and compare the colour of

the teeth with the colour of the face. The dentist should partially close his eyes to reduce light and compare artificial teeth of different shades with [lie colour of the face. The colour of the teeth that fades first from view is least conspicuous (contrasting) to the colour of the face.

Posterior teeth SelectionIt is classified under two divisions, namely:

Size of the teeth Form of the teeth.

Size of the Posterior TeethThe following factors are considered while selecting the

size of the teeth: Buccolingual width. Mesiodistal length. Ciedusogingival height.

Buccolingual WidthThe buccolingual width of the artificial teeth should be

decreased so that the buccal and lingual Surfaces slope out from the occlusal surface to provide a proper path of escapement of food during mastication.

It should be such that the forces from the tongue neutralize the forces of the check. If the buccolingual width increases, the forces acting on the denture will also increase, leading to increase in the rate of ridge resumption. Broader teeth encroach into the tongue space leading to instability of tire denture. Also, the teeth should not encroach into the buccal corridor space to avoid check biting.

Mesiodistat LengthThe mesiodistal length of each tooth should be selected

such that the combined length of all the posterior teeth on that side of the arch does not exceed the distance between the canine and the retromolar pad.

Posterior teeth should not be placed over steep antemposterior ridge slope as this would lead to forward displacement of the denture. Similarly the teeth should not be placed over displaceable tissues like the retromolar pad as it will cause tipping of the denture during function.

In cases with inadequate mesiodistal length, the premolar can be omitted.

Occluso-gingival HeightIt is determined by the available inter-arch distance. The

occlusal plane should be located at the midpoint of the interocclusal distance (Fig. 10.62). Large teeth selected for cases with inadequate interocclusal distance appear artificial and require modification before arrangement. Measures like altering the thickness of the denture base can also be done to accommodate large teeth.

Form of the Posterior TeethPosterior teeth are available in different forms. Before we

go into the details about each tooth form, we shall discuss the factors that control the w1oction of the form of a tooth.

Factors that control the selection of the form of a tooth: Condular incintion Teeth with a high cuspal height are

requires for patients with steep condylar guidance. This is because the jaw separation will increase for patients with acute condylar guidance during protrusion.

Height of Me residual rid e: Shallow cusped teeth go better with shallow ridges.

Palient's age: Teeth with shallow cusps am, preferred in older people.

Ridge reotionshipr: 0 @ or monoplane teeth tire preferred for cases with posterior cross bite or severe class II relationship.

Hanau's quint (discussed later).

Morphologically teeth can be classified as., Cusp teeth

- Anatomic teeth- Semi-anatomic or modified cusp or low cusp teeth

Cuspless teeth Special forms

Cusp TeethThey have cusps and fossae-like natural teeth. They are of

two types, namely anatomic and semi-anatomic. Cusp teeth can be used in the following occlusal schemes:

Bilateral balanced occlusion in centric and eccentric relations.

Balance in centric only. Non-intercepting cusp (modified occlusion).

Anatomic teeth These- teeth resemble normal newly-erupted teeth. They provide the best aesthetics and are the most commonly used type of artificial teeth. The cusps resemble normal dentition with an angle of 33 @ . Anatomic teeth with 30 @ cuspal angulations are also available and am, commonly known as Pilkington-Turner teeth.

Advantages of anatomic teeth Closely resembles natural teeth-highly aesthetic. Proper contours for crushing and triturating. Presence of adequate sluiceways. Greater chewing efficiency. excessive chewing pressure is

minimized. Mom vertical chewing stroke. Cuspal inclines provide a depth to obtain eccentric

balance. Provides a greater resistance to rotation of dentures. Provides a comfortable position to return to when cusps

are making contact in fossae.

Disadvantages of anatomic teeth More difficult and time consuming to obtain balanced

occlusion. Settling (stabilization of occlusion) results in more

damaging interferences. possibilities of more lateral stress in function. Settling also causes the vertical dimension at occlusion to

decrease and the mandible to move forward,

Settling will lead to residual ridge resorption.

Semi-anatomic TeethThey are also known as modified-cusp or low-cusp teeth.

They may have 20 @ or 10 @ cuspal angulation. l0 @ semi-anatomic teeth am commonly known as functional or anatoline teeth. They are used in cases with mild discrepancies in jaw relation. They are more flexible to arrange than anatomic teeth but then am not as flexible as non -anatomic teeth.

Advantages of semi-anatomic teeth Easier it, arrange and obtain balanced occlusion. Can provide freedom if settling occurs. Reduction of lateral stresses. Provides all the advantages of cusp teeth.

Disadvantages of semi-anatomic teeth Less aesthetic (buccal cusps are shorter) Leis chewing efficiency (controversial: some claim

greater)

Cuspless TeethThey are also known as 0 @, flat, or monoplane teeth. They

have no cuspal angulation hence are very flexible to vet. It is easy to vet non-anatomic teeth in balanced occlusion. Cuspless teeth can be used for the following occlusal schemes:

Bilateral balance with a compensating curve. Three-paint balance with a balancing ramp. Hat plane-balance in centric only. Reverse-pitch (Anti-Monson) curve.

Advantages of cuspless occlusal schemes More stable lower denture during mastication More vertical chewing stroke. More shear in the chewing stroke. More tongue room.

??????????????? schemes Less stability to the upper denture. No balance in excursive glides (unless plea-sure curve

added). Refer arrangement of teeth.

Advantages of 0i teeth Easy to set up. Least lateral stress. Least anterior-posterior interferences after settling. Best cur patients with poor muscular control. Best for patients with poor ridge relationships. Reduced buccolingual width, and sharp grooves and

sluiceways compensate for cusps in obtaining equal chewing efficiency.

Disadvantages of 0 6 teeth Very difficult to obtain balanced occlusion in excursive

movements. Less chewing efficiency especially for fibrous or tough

food. Poor aesthetics. When set on a flat plane, a space develops pos-tericirly

when excursions occur ("Christenson's phenomenon"), causing excessive pressure and resorption in the anterior region.

Special Tooth FormsThey include French's posteriors, coffee bars masticator,

VO posteriors, Sosin-bladed teeth and many others. Cutter bars and masticators are no longer available. These teeth am, discussed in detail in the first chapter under the parts of a complete denture.

Advantages Some can provide moderate to excellent function. To date, meet efficient design is Sosin bladed teeth.

Disadvantages Often aesthetics is poor. Best forms require meticulous execution and skill. More expensive Many commercially available forms are poorly designed

and have only "gimmick" value.

Selection of Teeth Based on the Type of Material UsedAcrylic, porcelain or new hard acrylics are the most

commonly used. Composite teeth are also available. Acrylic and porcelain teeth have been discussed in parts of a complete denture. Hard acrylic teeth show more resistant to wear and stains. Acrylic and porcelain teeth are discussed detail in parts of a complete denture in Chapter 1.

Teeth arrangement is the next step in the fabrication of a complete denture. Before we go into the principles of arrangement of teeth, we shall discuss the concepts of occlusion.