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|The Maryland Academy of General Dentistry|
Occlusion Guidelines for Restorative Dentistry:
Why, When and How should we use them?
Terry T. Tanaka, DDS, Clinical Professor,
Advanced Education in Prosthodontics
University of Southern California, School of Dentistry
Abstracted from the chapter on Occlusion Guidelines,
USC Manual for Graduate Residents
These notes are provided as a supplement to the program and are presented in an outline form for the doctors dental hygienists and dental staff. Specific questions will be asked and answers provided with references to the relevant literature for those interested.
What kinds of restorative problems would you expect to see related to occlusion, besides malocclusion?
Restoration fracture, chipping, debonding, marginal leakage, tooth wear, mobility, tooth pain and loss of vitality to mention just a few. It has been my experience that the etiology of these restorative problems lies more often with what the patient does with the restoration, e.g. bruxing, popcorn and hard candies than the physical properties of the material used in the fabrication of the restoration. This outline is provided as a summary of some of the guidelines taught in graduate programs in the hope that they will act as a guide to help you avoid some of the more difficult and unsuspecting problems.
My primary goal as a teacher for these many years has been to teach young doctors to "listen carefully and to think" in order to make sense of the patient's words and of the patient's story." And also to take the time to observe the patient quietly and carefully in order to develop the skill and caring every patient deserves.
Read carefully and enjoy the voyage
A taxonomy is a classification of different objectives that educators set for students (learning objectives).
I feel that the principal objective is to teach the student (doctor) to “think" through problems.
Although knowledge is presented in lectures, journal articles and books and comprehension is accomplished by visualizing (viewing, reading, hearing and writing notes, the ability to truly learn a skill is to be able to perform it in a workshop and hopefully before performing the procedure on a patient. Your AGD Mentors have provided you with this opportunity, welcome back to graduate school.
What guidelines will be addressed in this program?
- Growth and development and malocclusions
- How do gender and facial form affect the bite forces?
- Masticatory Function & Dysfunction
- How do patients chew, outside in or inside out?
- Force Management: how much force is applied when chewing, swallowing, biting, bruxing, day,night?
- Tooth Wear: when does the majority of tooth wear occur, diurnal (day) or night nocturnal?
- What forces should we consider? Occlusal, Interproximal?
- What clinical factors are affected by the above information?
What clinical factors are affected by the previous guidelines?
Static Occlusion: Centric Occlusion CO. ICP and MIP
- CO=CR (GPT-8) CO is the point where the mandibular teeth contact the maxillary teeth in the Centric Relation Position, CO is a “tooth contact position.”
- CR is a “Treatment Position.”
- MIP & ICP are the same position, (“close and swallow).
- Horizontal Overlap, (Overjet)
- Vertical Overlap, (Overbite)
- Curve of Spee, (Plane of Occlusion)
- Curve of Wilson, and OVD
- Vertical Dimension OVD, VME,
Dynamic Occlusion: Masticatory Function, biting, chewing, swallowing, clenching, grinding/bruxing, CNS movements
Evidence Based Dentistry, EBD:
How much evidence do we have for the dental treatments that are being performed today? (Evidence Based Dentistry)
7% to 8% of all dental treatments are evidence based and greater than 50% of general dentists in their study turn to friends and colleagues for evidence rather than looking in peer-reviewed journals, textbooks and electronic databases. Brian Fitzpatrick Int J Pros Vol.21,No.4;2008:358-363
“The objective of reading from a wider list of subjects and sources, is to allow us to view the subjects from different perspectives.”
“Sometimes they will be different from the views that we currently hold.”
Is this good or bad?“Cocooning” Sustain
What is the Role of Occlusion in 2015 and are we following the guidelines?
Occlusion Guidelines in Restorative Dentistry: 2015
1. Facial Guidelines: facial development and facial morphology
2. Guidelines for Masticatory Function
3. Guidelines for the management of occlusal forces and oral habits
4. Dental & Occlusion Guidelines: tooth size, tooth position,and tooth to tooth relationships, CR, MIP, OVD
5. Diagnosis and management of pain in clinical practice
6. Splint Therapy and pharmacology
Facial Guidelines: development and morphology
Females - face developed by age 15 to 16 (Woodside)
Males - face developed by age 18 to 19 (Woodside)
Skeletal Growth of the Jaws and Face
There is a growth spurt at age 8 and again at age 10 peaking at 12-13 and completing growth at age 15-16 in females. Woodside DG - (14-15 in other studies)
Both height and condylar growth experience a growth spurt from 12-14 and then the rate of growth decreases and is completed by age 18-19 in males. Woodside DG (15-16 in other studies)
Are there growth (remodeling) changes in adults after 30 years of age? “Yes,” Behrents, RG 1984
Craniofacial deformities,(cleft lip and palate) are operated before age one if possible.
Orthognathic surgery is usually delayed until age 16-18 in females and age 18-19 in males.
Dental implants are not placed until facial growth is completed.
Some facial plastic surgery procedures that involve osseous structures are delayed until facial growth is completed. Cranio-facial deformities excluded.
Facial Form & midline should be viewed from the front and from the sagittal.
Males can apply 2x the forces as females
Dolicofacial: long face, higher mandibular plane, narrow maxillary arch, high palatal vault and anterior of the maxillary sinus deficient for implants.
* Bite force may be ½ of the patient with a low mandibular plane (brachyfacial.)
If the anterior compartment is missing, the implants may be placed in the nasal cavity. The significance of facial morphology when placing implants
Dolicofacial- Long face – (apply less biting force)
Higher mandibular plane angle
Maxillary sinus- anterior compartments minimal to non-existent with risk of placing the implants in the nasal cavity.
There are different facial and dental norms for different ethnic groups
Ethnic Differences in Facial Form
23-33% Class II
Narrow max/mand arches
High palatal vault
More treated arch size discrepancies,(malocclusions)
23-33% edge to edge & Class III
Flat & wide palatal vault
Malocclusions involve max. canines crowded out labially
More tooth size discrepancies, malocclusions
Ethnic Differences: palatal vault, arch size, tooth size and shape. Perio. Tendency toward stripping of labial/buccal tissues w. expansion; Caucasian tendency toward edge to edge & cross-bite occ.
A longitudinal study on growth and development of dental arches of primary, mixed and permanent dentitions:
Posterior crossbite may affect craniofacial growth and development.
It was observed that children in the early mixed dentition with a long-face trend showed lower bite force and higher probability to present functional posterior crossbite. Castelo Braz Oral Res 2008
Crossbites in the developing dentition:
Crossbites of dental origin are due solely to displacement of teeth.
- They usually affect only some of teeth in an area of the arch,
- As a rule they are not as severe as cross bites due to jaw discrepancies (arch-size discrepancies).
- But this means that occlusal interferences are often present, increasing the chance of a shift on closure.
Whether or not these occlusal discrepancies initiate muscle and joint disorders will be presented in later lectures.
Crossbites of genetic origin – are due to pre-determined factors
Crossbites: Tongue factors
Clinical significance of tongue space for general dentists and surgeons
Skeletal Contributions to Malocclusions: (1) Proffitt/Fields/Sarver Contemporary Orthodontics, Quintessence
Facial convexity or concavity is the result of a disproportion in the size of the jaws:
(a) Vertical: Class I
(b) Convexity: Class II
(c) Concavity: Class III
Treatment Planning Guidelines in Restorative Dentistry & Orthodontics
The inclination of the incisors (90°-102°) Incisors should support the upper lip.
Problem Solving in Dentistry: Two Keys to Diagnosis:
“Listen to the patient” - They will tell you what the diagnosis is by the words (adjectives) they use to describe their pain or problems. (80% of diagnosis)
“Observe the patient,” their posture, their physical and emotional state, their mannerisms, and the study casts and lab tests carefully, and you will see the physical signs that are the keys to the diagnosis.
The Dental Examination begins with the Patient Interview.
“Pay Attention”and Listen to the patient as they speak and tell you their “Story,”
“Many listen but few actually hear.”
“Many observe, but only the skilled actually see.”
Observe the patient for the physical signs of disease and dysfunction. Consider the age, gender and facial form of the patient. What should the dentist know about the facial planes?
As you view the patient sagittally, consider the mandibular plane and the naso-labial angle, (90°-102°)
What do we need to know before we look at casts?
Who is the patient? Listen & “pay attention”
What does patient want? Let them tell their story
Why are they here? List the Chief Complaints in their own words?
Age of patient? Why is age a factor?”
Gender – M or F? Pain, bite force
Angle Orthodontic Classification of Malocclusions:
Angle Classification of Occlusion
Class I Normal molar relation
Class II Dental Malocclusion (Tooth size discrepancy)
- Class II molar relation with ant. deep bite and retroclined maxilllary incisors.
- Class II molar relation with ant.deep-bite and insufficient horizontal overlap.
Class II Skeletal Malocclusion (arch-size and/or position discrepancy)
Class III Skeletal Malocclusion – (ant. Edge to edge) arch-size discrepancy, growth factors, genetic, local and systemic disease)
Class III Skeletal Malocclusion - arch-size discrepancy, growth factors, genetic, local and systemic disease)
Centric Relation(CR) and Occlusal Interferences: the significance of “a slide from CR to MIP(ICP).”
The goal of removing the slide is to achieve contact of the U/L anterior teeth for anterior guidance. Is this necessary for all patients?
Many believe that the “slide” causes TMDs. May or may not be a valid hypothesis.
-90% of individuals have a “slide” from CR to MIP.
-Only 7% have TMDs (muscle and TMJ disorders)
- Class II Dental Occlusions are the result of tooth-size discrepancies, ectopic
eruption of teeth and other growth and development causes.
- Class II Skeletal Occlusions are the result of arch-size discrepancies, and other growth
and development causes.
-An“Equilibration of the teeth will not achieve coupling of the anterior teeth & is not indicated.”
- A centric record and mounted casts are required.
Mclaughlin Classification of Malocclusions:
McLaughlin, Angle Orthodontist 1988
Vertical Disorders - (open bites: anterior, posterior, unilateral; anterior deep-bite)
Horizontal Disorders - (cross-bite, edge to edge occlusion, Class III occlusion, anterior skids from CR to ICP, retrusive forces on closure e.g. “constricted envelope”)
Transverse Disorders: side to side, canted occlusal plane.
“How would you manage these four patients?”
What do we need to know before we look at casts?
Facial form – Brachyfacial, Mesofacial, Dolicofacial?
Facial mid-line - Facial asymetry, etiology
Dental mid-line – How many mm. off center?
Transverse occlusal plane- Parallel to the floor?
** Do you need mounted casts to determine the above information?
- TM Joint Stability and Restorative Treatments: How Stable is CR and Why?"
- When are mounted casts recommended?
- McLaughlin Classification of Malocclusions
- Facial trauma
- Vertical disorders- e.g. open bites, unilat. or bilateral.
- Tx of the post. vertical stops
- Altering the OVD
- Work up for orthognathic surgery; advancement and setback
- Complete rehabilitation of one or both arches
- Fabrication of sleep disorder appliances.
- Eval. occlusion at MIP and CR
When are mounted casts recommended and when are mounted casts not required?
a) Asymptomatic Patients (AP) with complete dentition and requiring a single (or two
b) AP with minimal or no occlusal wear requiring bucc./labial restorations; e.g. Cl.V, or
buccal cusp of max. teeth APs. With asymptomatic TMJs, who require routine dental
c)Treatment at same OVD
Should casts be mounted at CR or MIP?
MIP: Asymptomatic Pts.(AP), routine dental Tx, 1 or 2 restorations at same OVD
MIP for 85-90% of Pts.
MIP or CR for splints both before & after routine restorative Tx.
CR for more complex Tx
CR for complete arch Tx
CR for pre/post-rehab. Tx
CR if equilibration required.
The anterior slide or skid may result in wear of the lingual of the maxillary incisors and labial of the mandibular incisors. If inadequate posterior holding cusps are not present, wear may be seen at the incisal edges and eventually an anterior edge to edge relation may result.
Centric Relation Records: What do you use for CR records?
- Do you routinely use an articulator? Yes or No?
- What kind of articulator do you use for everyday restorations, bridges? –
Incisor display at rest: Vig RG, Brundo GC JPD 39:502-504, 1978; Sackstein M 2008 Int J Prostho
- at age 30 - 3.5mm
- at age 70 - 0.5mm
Tooth display of mandibular incisors:
- 0.5mm at age 30
- 3.0mm at age 70
* Dept. Plastic Surgery UCSD School of Medicine 1976-1990
* The position of the maxillary incisors should offer support for the upper lip. The lips
(entire face) will move downward with age with the rest of the face.
* “A Treatise on the Continuum of Growth In the Aging Craniofacial Skeleton”
Rolf G. Behrents, DDS, PhD, University of Michigan, Center for Human Growth and
Development, 1984, Ann Arbor, Michigan
- From age 37 to 77 the max. incisors move incisally 2-3mm, & the mand. incisors
move lingually 1-1.5mm & both arches shorten AP.
- Slides - The mean positional changes of the maxilla during adult life, for both
sexes combined are shown and the mean dimensional changes in the mandible for
males during adult life.
- "Incisor display at rest is a function of aging."