Malocclusion

Dental diagnosis
Overview
Angle Class I crowded malocclusion shows palatal constriction.

Figure 1: Note that the six-year molars (see arrows) are positioned “Angle Class I”. From the photograph, the patient’s main occlusal problem appears to be crowding; the upper jaw appears “constricted” (narrowed), and the upper front teeth are flared forward a bit. An evaluation of the jaw and facial bones using a cephalometric X-ray image is necessary to rule out a skeletal malocclusion. (Image courtesy Thomas J. Melcher, DDS, MS).

Malocclusion is the dental term for an improper bite relationship between the upper and lower teeth (Figure 1). In some cases, the misalignment is due to a size or positional mismatch between the jaw bones (the maxilla and mandible), and in some, it is the size or position of the teeth within the jawbones. Combinations are also possible. When the jawbones are mismatched, the condition is called a “skeletal malocclusion” (Figure 2). When the malocclusion is due to tooth size and position issues, the condition is called a “dentoalveolar malocclusion”.

Dentists use a system called “Angle Classification” to describe the relative closed-bite positions of the upper and lower first permanent molars and canines (measured forward-backward along the dental arches). The first permanent molars appear in the mouth around age six, and are an important determinant of how the patient’s overall bite relationship will develop.

Angle Class I is considered to be normal position (with the forward, outermost “mesiobuccal” cusp of the upper six-year molar resting in the “Buccal” groove of the lower six-year molar, between its cusps); Angle Class II is where the lower molars are positioned distal (toward the back of the mouth) of Class I position; Angle Class III is where the lower molars are positioned mesial (toward the front of the mouth) of Class I position.

Malocclusion ranges in severity from slightly tipped or rotated individual teeth, to poorly matched jaw bones, with undersized dental arches and oversized, crowded teeth. Depending on the severity of the patient’s malocclusion, significant problems can occur. These include abnormal wear (attrition), chipping /cracking, and premature loss of teeth; reduced chewing efficiency; improper nutrition; jaw joint pain, popping, clicking and/or locking (TMJ Disorders); reduced ability to perform effective oral hygiene; development of tooth decay (caries); development of periodontal disease; and what some may view as an unattractive smile.

Skeletal jaw size discrepancy malocclusion with large underbite mandibular prognathism.

Figure 2: This patient has a severe skeletal malocclusion (prognathic, oversized mandible, combined with an undersized maxilla), which would require a combination of orthognathic surgery and orthodontic treatment to correct. Unfortunately, the condition contributed to the premature loss of the patient’s lower front teeth (those shown in the photograph are denture teeth).

Terms used to describe positional features include “prognathic”, “retrognathic”, “overjet”, and “overbite”. Prognathic means one (or both) of the jaw bones is positioned too far forward (Figure 2). Maxillary prognathism means the upper jaw is positioned too far forward for the teeth to align properly. This condition also gives the face too much convexity when the patient is viewed in profile.

Retrognathic means one (or both) of the jaw bones is positioned too far backward. Mandibular retrognathism means the lower jaw is positioned too far back for the teeth to align properly. This has the some of the same effects on tooth alignment as maxillary prognathism.

Overjet is the term used to describe the horizontal distance between the outer biting edges of the upper and lower teeth when the patient has their teeth fully closed. Normally this distance is about 1 to 3 millimeters, with the upper teeth sitting outside of the lowers.

“Reverse overjet” or “underjet” is where the lower teeth sit outside the uppers when the patient closes fully together (Figure 2). Other terms used when the lower teeth close on the outside of the upper teeth include “crossbite”, and “reverse occlusion”.

“Overbite” is the vertical distance between the upper incisor biting edges and lower incisor biting edges when the patient has their teeth fully closed. Normally, the upper incisors overlap (on the outside of) the lower incisors by about 50% of the height of the lower incisor crowns.

“Underbite” is where the lowers incisors are positioned outside of the uppers when the patient is fully closed together. An “open bite” is where the upper and lower teeth do not make it as far as the closed bite plane, leaving the affected opposing teeth separated when the patient is biting together fully.

Ideal position and size of the jaws for proper alignment of the dental arches can be influenced while growth and development of the patient is still occurring. The specialty of dentistry known as orthodontics involves diagnosing and treating various types of malocclusion, so that the patient’s teeth close together with even force distribution when the jaw muscles are relaxed and the jaw joints are in a stable position. Orthodontists try to accomplish these goals while achieving esthetic facial proportions and an attractive smile.

How is this dental diagnosis established?
Diagnostic equilibration is first performed on casts of the teeth in dental malocclusion.

Figure 3: Dentists use diagnostic casts of the teeth for a variety of purposes when evaluating malocclusion. They can be used to evaluate how the teeth mesh. The additive widths of individual teeth can be measured to compare the space required to fit them all in the dental arch with the actual length of the dental arch. A “diagnostic equilibration” was performed on the casts in this photograph to see how much tooth structure would have to be removed to produce an evenly balanced bite relationship; and to decide whether orthodontic tooth movement and/or jaw surgery might be a better option.

Dentists visually evaluate the way the teeth fit together as part of a comprehensive examination. They check for abnormal tooth position, crowding, jaw size discrepancies (i.e. one jaw poorly matched to the size of the other), abnormal wear (attrition), chips and cracks. If malocclusion is suspected, the dentist may prescribe impressions / casts of the teeth (Figure 3), and a series of facial X-ray images. Most commonly these include panoramic (Figure 4) and cephalometric (Figure 5) radiographs).

Panoramic dental X-ray for assessment of developmental status.

Figure 4: Panoramic X-ray images are used to evaluate growth and development. Missing teeth can be identified, and measurements can be made of teeth which have not yet erupted to predict how much room will be needed in the dental arches for the permanent teeth.

Unless the general dentist provides orthodontic treatment, a referral to an orthodontist may be made. Some general dentists provide limited orthodontic treatment for relatively simple orthodontics cases, but prefer to have the more complex patients treated by a specialist. Orthodontists are dentists who have completed two to three years of additional studies following graduation from dental school, and specialize in diagnosing and treating malocclusions and facial development issues.

Orthodontic tracings on a lateral cephalometric X-ray.

Figure 5: Cephalometric X-ray images are used to measure distances and angles in the developing face and jaw bones. Measurements are compared to “normal” growth and development numbers, and a treatment plan for guiding the growth and development of the face and jaw bones is established. (Image courtesy Thomas J. Melcher, DDS, MS).

Evaluating children early for potential orthodontic issues is important. It is generally recommended that children be screened by an orthodontist around age seven. At this age, significant growth in the facial bones and jaws remains, and the patient generally has the permanent first molars and some of the permanent incisors.

Lack of spaces between the primary teeth is a reasonably good predictor of crowding in the permanent teeth. If a child has an obvious underbite or prognathic mandible, or other obvious significant malocclusion, referral for orthodontic screening prior to age seven may be recommended. At this young age, the jaws and facial bones of children are flexible, and the upper jaw is still in two pieces (the left and right halves of the maxilla fuse around the time of puberty). Influencing the development of the jaws and face at an early age is generally straightforward.

Treatment options

If malocclusion is suspected from a screening examination, casts of the teeth and radiographs (dental X-rays) are generally prescribed. Diagnostic photographs will also be taken. These diagnostic procedures are performed to produce records, which establish the patient’s starting point for treatment, a diagnosis, and the information needed to plan the best course of treatment.

Orthodontic treatment is the most common recommendation for malocclusions. If there is a significant skeletal component to the malocclusion, a large skeletal asymmetry, or a skeletal deformity, maxillofacial surgery may recommended. Usually this will require the patient to undergo orthodontic treatment before, at the time of, and even after surgery is performed.

If a patient is unable to undergo orthodontic treatment, it may be possible to adjust the way the teeth mesh in a procedure called occlusal adjustment. Limited occlusal adjustment may also be recommended to finely tune a patient’s occlusion (bite relationship) following orthodontic treatment. If teeth are undergoing rapid wear due to malocclusion, and orthdontic treatment is not an option, an occlusal guard may be recommended to decrease the wear rate of the teeth.

Sometimes there is so much crowding in the dental arches that extraction (removal) of one or more teeth may be recommended, either before orthodontic treatment is started, or while it is underway. It is common to have two to four bicuspid teeth removed, to create enough space for the other teeth in the dental arch.

If a patient’s bite relationship is within normal limits, and the primary concern is crowded or rotated teeth, it may be possible to reconstruct the visible surfaces of the patient’s teeth to produce the illusion of proper alignment with veneers or onlays.

Related diagnoses

Sometimes flat wear planes (facets) on the teeth are due to a tooth grinding habit (bruxism), and may be observed even on teeth that align properly with good distribution of biting forces among the teeth. Chips and cracks in the teeth may also be due to factitious habits, which means using the teeth for purposes other than chewing for nutrition.

Caries (decay) and periodontal disease may result from a patient’s limited ability to clean their teeth if the teeth are overlapped and crowded.

Author: Thomas J. Greany, D.D.S.
Editor: Ken Lambrecht
This page was reviewed by members of our review board.

This page was last updated on July 8, 2015.

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Related pages on ToothIQ.com

Attrition
Attrition
Bruxism
Bruxism
Caries
Caries
Casts
Casts
Crowns
Crowns
Equilibration
Equilibration
Factitious Habits
Factitious Habits
Night Guards
Night Guards
Onlays
Onlay
Orthodontics
Orthodontics
Periodontal Disease
Periodontal Disease
Photographs
Photographs
Simple Tooth Extractions
Simple Tooth Extractions
TMJ Disorders
TMJ Disorders
Veneers
Veneers
X-rays
X-rays

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Background information

Occlusion, TMDs, and dental education
Ash, Major M. Jr.
Head & Face Medicine
2007 3 (1)

Open Bite in Prematurely Born Children
Harila, V., et al.
Journal of Dentistry for Children
2007 74 (3): 165-170

Centric relation: A historical and contemporary orthodontic perspective
Rinchuse, Donald J., DMD, MS, MDS, PhD and Kandasamy, Sanjivan, BDSc, BScDent, DocClinDen, MOrthRCS
The Journal of the American Dental Association
2006 137 (4): 494-501

Photogrammetric Technique For Teeth Occlusion Analysis in Dentistry (PDF, 373K)
Kynaz, V.A. and Zheltov, S. Yu.
Image Engineering and Vision Metrology; International Archives of Photogrammetry, Remote Sensing and Spatial Information Sciences
2006: 25-27
Notes: From the Proceedings of the ISPRS Commission V Symposium, Dresden, Germany, 25–27 SEP 2006.
Editor’s notes: This study overlooks two essential elements in the establishment of proper occlusion—resting position of the jaw closing muscles, and stable position of the jaw joints; however, it is included because it presents a viable method of reproducing the stable, resting muscle position once established on the patient. Economic viability of performing the analysis as demonstrated seems questionable.

Supplemental mandibular central incisor
Bhat M.
Journal of Indian Society of Pedod Prev Dent
2006 24 (5): 20-23

Minimally invasive dentistry
Murdoch-Kinch, Carol Anne, DDS, PhD, and McLean, Mary Ellen, DDS
The Journal of the American Dental Association
2003 134: 87-95

Periodontic and orthodontic treatment in adults
Ong, Marianne M.A., BDS, MS and Wang, Hom-Lay, DDS, MSD
American Journal of Orthodontics & Dentofacial Orthopedics
2002 122 (4): 420-428

Relationship Between Dental Occlusion and Physical Fitness in an Elderly Population
Takayuki Yamaga, et al.
The Journals of Gerontology, Biological Sciences and Medical Sciences
2002 57: 616-620

Supernumerary Teeth—An Overview of Classification, Diagnosis and Management
Garvey, M. Therese B. Dent. Sc, D. Orth., M. Orth., M.Sc., FDS, et al.
Journal of the Canadian Dental Association
1999 65: 612-616

The decision to extract: Part 1—Interclinician agreement
Baumrind, Sheldon, DDS, MS, et al.
American Journal of Orthodontics & Dentofacial Orthopedics
1996 109 (3): 297-309

The decision to extract: Part II. Analysis of clinicians’ stated reasons for extraction
Baumrind, Sheldon, DDS, MS, et al.
American Journal of Orthodontics & Dentofacial Orthopedics
1996 109 (4): 393-402

An algorithm for ordering pretreatment orthodontic radiographs
Atchison, Kathryn A., DDS, MPH, et al.
American Journal of Orthodontics & Dentofacial Orthopedics
1992 102 (1): 29-44

Occlusion in the New Millennium: The Controversy Continues, Part 1 (PDF, 429K)
Spear, Frank, DDS, MSD
Spear Perspective—The art and science of exceptional esthetic and restorative dentistry
3 (2)
Editor’s notes: Great Lakes Orthodontics web site.

Occlusion in the New Millennium: The Controversy Continues, Part 2 (PDF, 112K)
Spear, Frank, DDS, MSD
Spear Perspective—The art and science of exceptional esthetic and restorative dentistry
3 (2)
Editor’s notes: Great Lakes Orthodontics web site.

Information you may wish to read before making a decision on treatment

Evaluation of a software program for applying the American Board of Orthodontics objective grading system to digital casts
Hildebrand, Jed C., et al.
American Journal of Orthodontics & Dentofacial Orthopedics
2008 133 (2): 283-289

Twenty-year follow-up of patients with permanently bonded mandibular canine-to-canine retainers
Booth, Frederick A., et al.
American Journal of Orthodontics & Dentofacial Orthopedics
2008 133 (1): 70-76

A comparison of treatment impacts between Invisalign aligner and fixed appliance therapy during the first week of treatment
Miller, Kevin B., et al.
American Journal of Orthodontics & Dentofacial Orthopedics
2007 131 (3): 302.e1-302.e9

An Overview of Invisalign® Treatment (PDF, 600K)
Josell, Stuart D., DMD, MDent Sc and Siegel, Steven M., DMD
University of Maryland Dental School
2007
Notes: Spring 2007, Continuing Education Course from The Baltimore College of Dental Surgery

Assessing the American Board of Orthodontics objective grading system: Digital vs. plaster dental casts
Okunami, Troy R., et al.
American Journal of Orthodontics & Dentofacial Orthopedics
2007 131 (1): 51-56

Dental health assessed more than 10 years after interproximal enamel reduction of mandibular anterior teeth
Zachrisson, Bjorn U., et al.
American Journal of Orthodontics & Dentofacial Orthopedics
2007 131 (2): 162-169

Electromyographic activity of the temporal and masseter muscles at different occlusal positions
Petrovic, D. and Horvat-Banic S.
Medicinski Pregled (Novi Sad)
2007 60: 134-139

Invisalign and Traditional Orthodontic Treatment Postretention Outcomes Compared Using the American Board of Orthodontics Objective Grading System
Kuncio, Daniel, et al.
The Online Angle Orthodontist
2007 77 (5): 864-869

Unexpected complications of bonded mandibular lingual retainers
Katsaros, Christos, et al.
American Journal of Orthodontics & Dentofacial Orthopedics
2007 132 (6): 838-841

Is there an association between occlusion and periodontal destruction?
Harrel, Stephen K. DDS, et al.
The Journal of the American Dental Association
2006 137 (10): 1380-1392

Variations in orthodontic treatment planning decisions of Class II patients between virtual 3-dimensional models and traditional plaster study models
Whetten, Joshua L., et al.
American Journal of Orthodontics & Dentofacial Orthopedics
2006 130 (4): 485-491

Clinical trials needed to answer questions about Invisalign
Turpin, David L.
American Journal of Orthodontics & Dentofacial Orthopedics
2005 127 (2): 157-158

Is occlusion becoming more confusing? A plea for simplicity
Christensen, Gordon J., DDS, MSD, PhD
The Journal of the American Dental Association
2004 135 (6): 767-770

Comparison of measurements made on digital and plaster models
Santoro, Margherita, DDS, MA, et al.
American Journal of Orthodontics & Dentofacial Orthopedics
2003 124 (1): 101-105

Congenitally missing teeth: Orthodontic management in the adolescent patient
Kokich, Vincent O., DMD, MSD
American Journal of Orthodontics & Dentofacial Orthopedics
2002 121 (6): 594-595

Now is the time to observe and treat dental occlusion
Christensen, Gordon J., DDS, MSD, PhD
The Journal of the American Dental Association
2001 132 (1): 100-102

Management of space problems in the primary and mixed dentitions
Ngan, Peter, DMD, et al.
The Journal of the American Dental Association
1999 130 (9): 1330-1339

Stability of orthodontic treatment outcome: Follow-up until 10 years postretention
Al Yami, Essam A., DDS, et al.
American Journal of Orthodontics & Dentofacial Orthopedics
1999 115 (3): 300-304

The mandibular central incisor, an extraction option
Klein, Douglas J., DDS, MSD
American Journal of Orthodontics & Dentofacial Orthopedics
1997 111 (3): 253-259

Abnormal occlusal conditions: a forgotten part of dentistry
Christensen, Gordon J., DDS, MSD, PhD
The Journal of the American Dental Association
1995 126 (12): 1667-1668

How occlusal forces change in implant patients: A clinical research report
Dario, Lawrence J. DMD, FACP, FICOI
The Journal of the American Dental Association
1995 126 (8): 1130-1133

The morphologic basis for the extraction decision in Class II, Division 1 malocclusions: A comparative study
Bishara, Samir E., BDS, DDS, DOrtho, MS, et al.
American Journal of Orthodontics & Dentofacial Orthopedics
1995 107 (2): 129-135

The functional impact of extraction and nonextraction treatments: A long-term comparison in patients with borderline, equally susceptible class II malocclusions
Beattie, John R., DDS, MSD, et al.
American Journal of Orthodontics & Dentofacial Orthopedics
1994 105 (5): 444-449

Treating Bruxism and Clenching (Letter #1)
The Journal of the American Dental Association
Editor’s notes: Editorial comment re: Dr. Christensen’s recommended treatments for bruxing- discusses mandibular rest and isokinetic stretching, used successfully for 40 years, by Dr. James H.Quinn, DDS.

Treating Bruxism and Clenching (Letter #2)
The Journal of the American Dental Association
Editor’s notes: Editorial comment re: Dr. Christensen’s recommended treatment for bruxing in young patients- discusses possible orthodontic complications from splint use in growing patients, by David J. Harnick, DDS, MSD (orthodontist).