“dental morphology: using the right instrument for the job!

Dental Morphology: Using the Right

Instrument for the Job!

Presented by:

Sara Beres

&

Janine Sasse-Englert

Dental Anatomy Review

• Historically, emphasis in dental hygiene education was placed on the importance of crown anatomy.

• Since the 1970’s, detailed knowledge of the root anatomy has been emphasized.

• Today’s literature supports the importance of precise root instrumentation.

• Root Morphology in Periodontal Therapy

Today’s Course Objectives….

• Review of Tooth Features

• Review of Root Concavities

• Review of Furcation Morphology

• Instruments to help YOU debride those areas

Copyright © 2016, 2011, 2006 by Saunders, an imprint of Elsevier Inc. All rights reserved.

44

Permanent Anterior

Teeth Properties

Permanent anterior teeth include the incisors

and canines.

Figure 16-1

4

(Courtesy of Margaret J. Fehrenbach, RDH, MS.)


55

Succedaneous

All permanent anterior

teeth are

succedaneous teeth.

Each one replaces the

primary teeth of the

same type.

Figure 6-22, A

5

(Adapted with permission from Schour I, Massler M: The development

of the human dentition, J Am Dent Assoc 28:1153-1160, 1941.)


66

Lobes

All anterior teeth are

thought to be

composed of four

developmental lobes

3 labial lobes

(mesiolabial, middle

labial, and distolabial)

1 lingual lobe Figure 16-2

6


77

Developmental Depressions

Two vertical labial developmental depressions outline the separations among the labial developmental lobes

ML and DL developmental depressions.

Figure 16-2

7


88

Incisal Ridge

An anterior tooth has an incisal surface

Considred the incisal ridge

Its masticatory surface or chewing surface.

Figure 16-3

8


99

Tooth Form

Crown outline of

the anteriors from

the proximal of is

triangular.

Apex at the incisal

ridge and the base

of the triangle at the

cervix. Figure 16-4

9


1010

Tooth Form

The incisors

function as

instruments for

biting and cutting

food during

mastication

because of their

triangular proximal

form.

10

#8—Mesial view


1111

Tooth Form

The canines,

because of their

tapered shape and

their prominent

cusp, function to

pierce or tear food

during mastication.

11

#11—Lingual view


1212

Height of Contour

Anterior Teeth Height of Contour-greatest elevation

(greatest pooch )

For both the crown’s labial and lingual surfaces is in the cervical third.

Figure 16-4

12


1313

Contact Areas

Contact areas of

anteriors are usually

centered labiolingually

on their proximal

surfaces.

Have a smaller area

than the contacts of

posteriors. Figure 15-10

13


1414

Cementoenamel Junction

On each proximal

surface, the CEJ

curvature of all

anteriors is greater

than that of the

posteriors.

Figure 16-4

14


1515

Cingulum

The lingual surfaces

of all anteriors have a

cingulum, which is a

raised, rounded

area on the cervical

third of the lingual

surface in varying

degrees of

prominence or

development. Figure 16-5

15


1616

Marginal Ridge

Ridges may also be

present on the

lingual surface.

The lingual surface on

anteriors is bordered

mesially and distally

on each side by a

rounded raised

border, the marginal

ridge. Figure 16-5

16


1717

Fossa/Fossae

Some anteriors

have a more

complex lingual

surface with a fossa

(plural, fossae),

which is a shallow,

wide depression.

Figure 16-6

17


1818

Developmental Pits

Some may also have

developmental pits,

which are located in

the deepest part of

each fossa.

Figure 16-6

18


1919

Developmental Groove

Other anteriors may have on their lingual surface a developmental groove (or primary groove), a sharp, deep, V-shaped linear depression that marks the junction among the developmental lobes.

19

Figure 16-6


2020

Supplemental Groove

In addition, a

supplemental

groove (or secondary

groove) may also be

present on the lingual

surface of anteriors,

which is a shallower,

more irregular linear

depression than the

developmental

groove.

20

Figure 16-6


2121

Root

Anteriors usually have one single root.

May also have root concavities or depressions as the root is viewed from the proximal.

21


2222

Root in Cross Section

(From Darby ML, Walsh M: Dental hygiene: theory and

practice, ed 4, St Louis, 2015, Mosby/Elsevier.)

22

Three Basic Shapes

• Triangular: maxillary incisor

• Ovoid (egg-shaped): canines

• Elliptic: mandibular incisors

• Roots that appear triangular

or ovoid in cross-section

have narrower lingual

surfaces


2323

Root

Maxillary anterior teeth roots

has great lingual inclination.

Mandibular anterior teeth

roots varies in angulation

from nearly vertical to great

lingual inclination

Figure 20-9

23

Maxillary Central Root Anatomy

KEY CONCEPTS TO REMEMBER:

- Single Conical shaped, relatively straight root

- Cross section: wider at labial and narrower at lingual, creating a rounded triangular shape

- Bulbous crowns may create deep mesial and distal concavities at the CEJ

Maxillary Lateral Root Anatomy


- Single, narrow root widest labiolingually and narrowest mesiodistally

- Cross section: ovoid shape

(lingual marginal groove) may be present on crown and root

Instrument Suggestions for Maxillary Incisor Challenges

Challenge: periodontal pocket associated with lingual groove on maxillary lateral

Try:

Straight explorer

Mini blade curette

Micro blade curette

Explorers

• Need something long and straight for deeper, narrow pockets

• TU 17

• #3, #3A

• Orban

• 11/12 has too many bends for a narrow pocket

TU 17 at left3A below

Curettes

• Need something long, straight, small blade, round toe

• Gracey 1/2 mini blade• Area specific

• 70 degree angle between face of blade and shank

• Langer 5/6 mini blade• Universal

• 90 angle between face of blade and shank

File

• Diamondtec M/D 7• Careful adaptation

to the groove

Instrument Suggestions for Maxillary Incisor Challenges

• Challenge: grooves and fossae collect stain

• Try:

• O’Hehir

• Excavator

• Discoid Cleoid

• Toe of posterior curet

-“Scoop” : Edge of scoop is sharp and can remove stain and calculus-Excavator: Your office may have several; keep one sterile for that special situation-Cleoid end of discoid/cleoid good for the grooves; Discoid end good for the fossae

Specialty Instruments

• Look for double ended, multi-purpose instruments

• Nebraska 128 paired with a Langer 5 mini

• Ideal pointed tip for groove and interproximals

• Ideal rounded toe for fossae, pockets

Mandibular Central Root AnatomyKEY CONCEPTS TO REMEMBER:

- Simple root, widest labiolingually, then mesiodistally

- Cross section: narrow oval

- Shallow depression extends longitudinally along mid-portion of root.

Mandibular Lateral Root Anatomy


- Root slightly thicker and wider than central

- With more pronounced longitudinal root depressions

- Cross section: slight hourglass

Instrument Suggestions for Mandibular Incisor Challenges

• Similar to maxillary

• These teeth are even more narrow; deep pockets hard to access with anything except a straight probe, straight explorer, mini curette blade

• Keep the longitudinal grooves in mind

• Similar fossa without the groove, less pronounced

• Tendency for heavy supragingival calculus build-up

Straight explorer

Keep the toe adapted as you walk around the line angle to get into the mesial and distal longitudinal root depressions

Regular size blade unlikely to fit mandibular incisors subgingivally

Toe is likely off root and in tissue if you try to use a regular blade

Curved blade, rounded back; prevent tissue trauma as you walk around the line angle, allow access to root longitudinal grooves

Instrument Suggestions for Mandibular Incisor Challenges

• Challenge:• Large bridge of calculus

• Can’t use ultrasonic

• Try• Chisel = push

• Hoe = pull

Push from the facial; bridge of calculus comes off on the lingual

Get more bang for your buck

• Use double-ended instruments with different ends

• Pair a hoe or chisel with a sickle

• Pair a universal curette with a small sickle

• Pair two different size sickles, one for heavy, one for fine

Maxillary Canine Root Anatomy


- Largest and strongest single roots for either arch

- 17 mm LONG!


- Possibility of moderate to deep longitudinal grooves

Mandibular Canine Root Anatomy


- 15 mm LONG!

- Longitudinal root depressions may extend full length of root

- Depressions may be EXTREMELYpronounced to the point of creating a facial and lingual component in the apical third

Instrument Suggestions for Maxillary and Mandibular Canines

• Need a long enough sickle blade to reach halfway across the interproximal surface, and it needs to be small enough (width) to fit right up under the contact.

• Need a long toe to curve into that longitudinal groove

• Need a long shank to reach a deeper pocket

Gracey 7/8 has a long bladeSome sickles much longer blades than others


6060

Permanent Posterior

Teeth Properties

The permanent posterior teeth include the

premolars and molars.

Figure 17-1

60

(Courtesy of Margaret J. Fehrenbach, RDH, MS.)


6161

Occlusal Surface

The crown of each

posterior tooth has an

occlusal surface as its

masticatory surface

Includes:

Marginal ridges

2 or more cusps

Triangluar ridges

Transverse ridges

Fossa, Pits and

Developmental Grooves

Figure 17-2

61


6262

Height of Contour- Posteriors

Buccal surface is in the

cervical third

Lingual surface is in the

middle third

When compared with

anteriors, most of the

posteriors are wider LL

than MD, except for the

mandibular molars.Figure 17-6

62


6363

Contact Area

In another comparison

with anteriors, the

contact area of each

of the posteriors is

wider, usually located

to the buccal of

center, and is nearer

the same level on

each proximal

surface.

Figure 15-10

63


6464

Cementoenamel Junction

On each proximal surface is a CEJcurvature that is less pronounced on the posteriors than on the anteriors.

The CEJ is often quite straight for posteriors.

64

Figure 17-6


6565

Roots

Can have two roots,

which means it is

bifurcated (Mand.

Molars)

65

Or with three roots,

which means it is

trifurcated (Max.

Molars)


6666

Roots

Premolars and molars

originate as a single

root on the base of the

crown.

This part on these

posterior teeth is

considered the root

trunk.

Figure 17-7

66


6767

Furcations

An area between two

or more of these root

branches, before they

divide from the root

trunk, is a furcation.

67

Figure 17-7


6868

Furcations

68

(All data from Nelson S: Wheeler’s dental anatomy, physiology, and occlusion, ed 10,

Philadelphia, 2015, Saunders/Elsevier.)

Maxillary First Premolar Root AnatomyKEY CONCEPTS TO REMEMBER:

- Typically bifurcated in apical or middle third, forming facial or lingual root- 61% of the time

- SINGLE ROOT- Mesial Surface has distinct longitudinal

groove which may be relatively shallow to deep enough to bifurcate the root

- Mesial surface groove makes this tooth periodontally fragile!

- Cross section: kidney shaped


- Typically bifurcated in apical or middle third, forming facial or lingual roots

- BIFURCATED ROOT- Mesial surface has distinct

longitudinal groove extending from the contact area to the bifurcation

- Distal surface has a groove, but reduced in depth, creating a convex or flat surface

Maxillary First Premolar Root Anatomy

7 mm Root Trunk!

Maxillary Second Premolar Root Anatomy


- Single root (generally)


- Mesial groove not as pronounced as first molar

Instrument Suggestions for Maxillary Premolar Challenges

• Challenge• Calculus in mesial

depression on max 1st

premolar

• Try• Curved explorer like

11/12

• Long and curved blades to reach depression

Access that Mesial Depression

Mandibular First/Second Premolar Root Anatomy


- Single root (generally)


- Large crowns and narrow roots with possible root depressions

Instrument Suggestions for Mandibular Premolar Challenges

• Challenge• Calculus on distals under

a bulbous crown, usually from the lingual

• Try• Posterior sickle with a

blade long enough to reach at least halfway across interproximal, thin enough to reach right up under the contact.

• Exaggerated roll to keep tip on the root

Maxillary First Molar Root Anatomy

- 3 roots: palatal (lingual), mesiobuccal, distobuccal

- Palatal root is the largest and the longest- Mesiobuccal root is the widest

Maxillary First Molar Root Anatomy3 furcation entrances: Mesial, Facial, Distal

- Facial Furcation - 4mm from CEJ

Maxillary First Molar Root Anatomy

3 furcation entrances: Mesial, Facial, Distal

- Mesial Furcation - 3mm from CEJ and not centered

- Broad, flat mesiobuccal root

- Best approached from the lingual since the palatal root is not as broad as the mesiobuccal root

- The inner or distal surface of the MB root usually has a longitudinal cavity.

- Minimal loss of periodontal attachment, the furcation is invaded

Maxillary First Molar Root Anatomy3 furcation entrances: Mesial, Facial, Distal

- Distal Furcation - 5mm from CEJ

- Very common to be periodontallyinvolved.

Maxillary Second Molar Root Anatomy

Similar to maxillary first, except roots are closer together creating tighter furcation entrances

Mandibular First Molar Root Anatomy

Two roots: Mesial and Distal

Two furcation entrances: developmental depression on facial and lingual root trunk from bifurcation to CEJ.


2 furcation entrances: Buccal and Lingual

- Buccal Furcation - 3mm from CEJ to

furcation

- Deep depression on mesial root


2 furcation entrances: Buccal and Lingual

- Lingual Furcation - 4mm from CEJ to furcation

- Slight depression on distal root

- Furcation is generally narrow and difficult to instrument

Mandibular Second Molar Root Anatomy

Similar to mandibular first, except all depressions are shallower.

Instrument Suggestions for Molar Challenges

• Challenge• Access furcations

• Try• Nabors probe

• Round file

• O’Hehir

• Mini curette toe

• Furcations are in the middle of the surface with the exception of the maxillary 1st molar mesial furcation

• Access easier from lingual

Nabors probe

Cleaning furcations

• file • O’Hehir

Round file in furcation

O’Hehir scoops in furcation

Mini curette – once inserted, turn to get rounded toe in furcation


• Challenge• Keeping appropriate

working angulation on posterior interproximal surfaces

• Try• Posterior sickle

• Gracey 15/16, 17/18

• Langer 17/18

• McCalls universal

• Curvature of the shank key

11/12 15/16 13/14 17/18

Don’t be afraid to . . . Let go

Dr. Gracey designed his instruments in the 1940s when stand up dentistry was practiced, before ergonomics were ever considered, before cumulative stress disorders were ever heard of. Don’t be afraid to try new instruments and let go of the old – AS LONG AS neither you nor the patient is harmed in the process.

Blade too open (more than 70°) with the 11/12, more effective blade angulation with 15/16

Langer CurettesUNIVERSAL Blade : GRACEY Shank

With a Langer, you have to tip the terminal shank toward the surface you’re scaling. When the terminal shank is parallel, the blade is too open.They are very efficient – can go from toward surfaces to away surfaces in anterior, or mesial of one tooth right to distal of the next in posterior, without switching instruments.

Same Challenge with sickles

Shank design


• Challenge• Root planing

• Try• Queen of Hearts

More challenges

• Probing the distal of molars, especially 3rds, especially maxillary

• Right angle probe

Keeping the tip on the tooth can be nearly impossible on maxillary 3rd molars –patient can’t open wide enough for the handle to drop far enough

McCalls 17/18• Distal root depression

of more posterior molars

• Posterior line angles

• Horizontal strokes• Very short

• Very controlled

REFERENCES

• Fehrenbach, Margaret J, Tracy Popowics, and Mary Bath-Balogh. Illustrated Dental Embryology, Histology, And Anatomy. Print.

• Jarrell, Beverly and James Padgett. "Root Anatomy And Instrumentation". Access (1994): 43-46. Print.

• McKechnie, Lucinda. "Root Morphology In Periodontal Therapy". Dental Hygienist News 6.1 n. pag. Print.

• Sharuga, Constance. "Furcation Anatomy". Dimensions of Dental Hygiene (2010): 36-39. Print.

“dental morphology: using the right instrument for the job!

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