A malocclusion is a misalignment or incorrect relation between the teeth of the two dental arches when they approach each other as the jaws close. The term was coined by Edward Angle, the "father of modern orthodontics", as a derivative of occlusion. This refers to the manner in which opposing teeth meet (mal- + occlusion = "incorrect occlusion").
|Dental problem in 10-year-old girl|
Signs and symptomsEdit
Malocclusion is a common finding, although it is not usually serious enough to require treatment. Those who have more severe malocclusions, which present as a part of craniofacial anomalies, may require orthodontic and sometimes surgical treatment (orthognathic surgery) to correct the problem. Correction of malocclusion may reduce risk of tooth decay and help relieve excessive pressure on the temporomandibular joint. Orthodontic treatment is also used to align for aesthetic reasons.
Malocclusions may be coupled with skeletal disharmony of the face, where the relations between the upper and lower jaws are not appropriate. Such skeletal disharmonies often distort sufferer's face shape, severely affect aesthetics of the face, and may be coupled with mastication or speech problems. Most skeletal malocclusions can only be treated by orthognathic surgery.
Depending on the sagittal relations of teeth and jaws, malocclusions can be divided mainly into three types according to Angle's classification system published 1899. However, there are also other conditions, e.g. crowding of teeth, not directly fitting into this classification.
Many authors have tried to modify or replace Angle's classification. This has resulted in many subtypes and new systems (see section below: Review of Angle's system of classes).
A deep bite (also known as a Type II Malocclusion) is a condition in which the upper teeth overlap the lower teeth, which can result in hard and soft tissue trauma, in addition to an effect on appearance. It has been found to occur in 15-20% of the US population.
An open bite is a condition characterised by a complete lack of overlap and occlusion between the upper and lower incisors. In children, open bite can be caused by prolonged thumb sucking. Patients often present with impaired speech and mastication.
Angle's classification methodEdit
Edward Angle, who is considered the father of modern orthodontics, was the first to classify malocclusion. He based his classifications on the relative position of the maxillary first molar. According to Angle, the mesiobuccal cusp of the upper first molar should align with the buccal groove of the mandibular first molar. The teeth should all fit on a line of occlusion which, in the upper arch, is a smooth curve through the central fossae of the posterior teeth and cingulum of the canines and incisors, and in the lower arch, is a smooth curve through the buccal cusps of the posterior teeth and incisal edges of the anterior teeth. Any variations from this resulted in malocclusion types. It is also possible to have different classes of malocclusion on left and right sides.
- Class I: Neutrocclusion Here the molar relationship of the occlusion is normal or as described for the maxillary first molar, but the other teeth have problems like spacing, crowding, over or under eruption, etc.
- Class II: Distocclusion (retrognathism, overjet, overbite) In this situation, the mesiobuccal cusp of the upper first molar is not aligned with the mesiobuccal groove of the lower first molar. Instead it is anterior to it. Usually the mesiobuccal cusp rests in between the first mandibular molars and second premolars. There are two subtypes:
- Class II Division 1: The molar relationships are like that of Class II and the anterior teeth are protruded.
- Class II Division 2: The molar relationships are Class II but the central are retroclined and the lateral teeth are seen overlapping the centrals.
- Class III: Mesiocclusion (prognathism, Anterior crossbite, negative overjet, underbite) In this case the upper molars are placed not in the mesiobuccal groove but posteriorly to it. The mesiobuccal cusp of the maxillary first molar lies posteriorly to the mesiobuccal groove of the mandibular first molar. Usually seen as when the lower front teeth are more prominent than the upper front teeth. In this case the patient very often has a large mandible or a short maxillary bone.
Review of Angle's system of classes and alternative systemsEdit
A major disadvantage of classifying malocclusions according to Angle's system is that it only takes into consideration the two-dimensional viewing along a spatial axis in the sagittal plane in the terminal occlusion, even though occlusion problems are, in principle, three-dimensional. Deviations in other spatial axes, asymmetric deviations, functional faults and other therapy-related features are not recognised. Another shortcoming is the lack of a theoretical basis of this purely descriptive classification system. Among the much discussed weaknesses of the system is the fact that it only considers the static occlusion, that it does not take into account the development and causes (aetiology) of occlusion problems and it disregards the proportions (or relationships in general) of teeth and face. Thus, numerous attempts have been made to modify the Angle system or to replace it completely with a more efficient one, but Angle's classification continues to prevail mainly because of its simplicity and clarity.
Well-known modifications to Angle's classification date back to Martin Dewey (1915) and Benno Lischer (1912, 1933). Alternative systems have been suggested by, among others, Simon (1930, the first three-dimensional classification system), Jacob A. Salzmann (1950, with a classification system based on skeletal structures) and James L. Ackerman and William R. Proffit (1969).
Crowding of teethEdit
Crowding of teeth is where there is insufficient room for the normal complement of adult teeth.
Extra teeth, lost teeth, impacted teeth, or abnormally shaped teeth have been cited as causes of malocclusion. A small underdeveloped jaw, caused by lack of masticatory stress during childhood, can cause tooth overcrowding. Ill-fitting dental fillings, crowns, appliances, retainers, or braces as well as misalignment of jaw fractures after a severe injury are other causes. Tumors of the mouth and jaw, thumb sucking, tongue thrusting, pacifier use beyond age 3, and prolonged use of a bottle have also been identified as causes.
In an experiment on two groups of rock hyraxes fed hardened or softened versions of the same foods, the animals fed softer food had significantly narrower and shorter faces and thinner and shorter mandibles than animals fed hard food. Experiments have shown similar results in other animals, including primates, supporting the theory that masticatory stress during childhood affects jaw development. Several studies have shown this effect in humans. Children chewed a hard resinous gum for two hours a day and showed increased facial growth.
During the transition to agriculture, the shape of the human mandible went through a series of changes. The mandible underwent a complex series of shape changes not matched by the teeth, leading to incongruity between dental and mandibular form. These changes in human skulls may have been "driven by the decreasing bite forces required to chew the processed foods eaten once humans switched to growing different types of cereals, milking and herding animals about 10,000 years ago."
Crowding of the teeth is treated with orthodontics, often with tooth extraction, clear aligners, or dental braces, followed by growth modification in children or jaw surgery (orthognathic surgery) in adults. Surgery may be required on rare occasions. This may include surgical reshaping to lengthen or shorten the jaw (orthognathic surgery). Wires, plates, or screws may be used to secure the jaw bone, in a manner similar to the surgical stabilization of jaw fractures. Very few people have "perfect" alignment of their teeth. However, most problems are very minor and do not require treatment.
Class II Division 1Edit
Low- to moderate- quality evidence suggests that providing early orthodontic treatment for children with prominent upper front teeth (class II division 1 malocclusion) is more effective for reducing the incidence of incisal trauma than providing one course of orthodontic treatment in adolescence. There do not appear to be any other advantages of providing early treatment when compared to late treatment. Low-quality evidence suggests that, compared to no treatment, late treatment in adolescence with functional appliances is effective for reducing the prominence of upper front teeth.
Class II Division 2Edit
There is no evidence from clinical trials to recommend or discourage any type of orthodontic treatment to correct deep bite and retroclined upper front teeth (Class II division 2 malocclusion) in children. A 2018 Cochrane systematic review anticipated that the evidence base supporting treatment approaches for Class II division 2 malocclusion is not likely to improve due to the low prevalence of the condition and the ethical difficulties in recruiting people to participate in a randomized controlled trials for treating this condition.
- Deep bite
- The most common corrective treatments available are fixed or removal appliances (such as dental braces), which may or may not require surgical intervention.
- Open bite
- Open bite is a difficult malocclusion to treat due to its corrective uncertainty. Treatment options for adults include a combination of extractions, fixed appliances, intermaxillary elastics and orthognathic surgery. However, treatment for children and adolescents is a controversial matter still undergoing debate. Those used include posterior bite blocks and headgear appliances.
Tooth size discrepancyEdit
To establish appropriate alignment and occlusion, the sizes of upper and lower front teeth, or upper and lower teeth in general, need to be proportional. Inter-arch tooth size discrepancy (TSD) is defined as a disproportion in the mesio-distal dimensions of teeth of opposing dental arches, which can be seen in 17% to 30% of orthodontic patients.
Other kinds of malocclusions can be due to tooth size or horizontal, vertical, or transverse skeletal discrepancies, including skeletal asymmetries. Long faces may lead to open bite malocclusion, while short faces can be coupled to a Deep bite malocclusion. However, there are many other more common causes for open bites (such as tongue thrusting and thumb sucking), and likewise for deep bites. The upper or lower jaw can be overgrown or undergrown, leading to Class II or Class III malocclusions that may need corrective jaw surgery or orthognathic surgery as a part of overall treatment, which can be seen in about 5% of the general population.
In the active skeletal growth, mouthbreathing, finger sucking, thumb sucking, pacifier sucking, onychophagia (nail biting), dermatophagia, pen biting, pencil biting, abnormal posture, deglutition disorders and other habits greatly influence the development of the face and dental arches.
Malocclusion can occur in primary and secondary dentition. In primary dentition malocclusion is caused by:
- Underdevelopment of the dentoalvelor tissue.
- Over development of bones around the mouth.
- Cleft palate.
- Overcrowding of teeth.
- Abnormal development and growth of teeth.
In secondary dentition malocclusion is caused by:
- Periodontal disease.
- Overeruption of teeth.
- Gruenbaum, Tamar. Famous Figures in Dentistry Mouth – JASDA 2010;30(1):18
- Thilander B, Pena L, Infante C, Parada SS, de Mayorga C (April 2001). "Prevalence of malocclusion and orthodontic treatment need in children and adolescents in Bogota, Colombia. An epidemiological study related to different stages of dental development". European Journal of Orthodontics. 23 (2): 153–67. doi:10.1093/ejo/23.2.153. PMID 11398553.
- Borzabadi-Farahani A, Borzabadi-Farahani A, Eslamipour F (October 2009). "Malocclusion and occlusal traits in an urban Iranian population. An epidemiological study of 11- to 14-year-old children". European Journal of Orthodontics. 31 (5): 477–84. doi:10.1093/ejo/cjp031. PMID 19477970.
- Millett DT, Cunningham SJ, O'Brien KD, Benson PE, de Oliveira CM (February 2018). "Orthodontic treatment for deep bite and retroclined upper front teeth in children". The Cochrane Database of Systematic Reviews. 2: CD005972. doi:10.1002/14651858.cd005972.pub4. PMC 6491166. PMID 29390172.
- Brunelle JA, Bhat M, Lipton JA (February 1996). "Prevalence and distribution of selected occlusal characteristics in the US population, 1988-1991". Journal of Dental Research. 75 (2 Suppl): 706–13. doi:10.1177/002203459607502S10. PMID 8594094.
- de Castilho LS, Abreu MH, Pires e Souza LG, Romualdo LT, Souza e Silva ME, Resende VL (January 2018). "Factors associated with anterior open bite in children with developmental disabilities". Special Care in Dentistry. 38 (1): 46–50. doi:10.1111/scd.12262. PMID 29278267.
- Feres MF, Abreu LG, Insabralde NM, Almeida MR, Flores-Mir C (June 2016). "Effectiveness of the open bite treatment in growing children and adolescents. A systematic review". European Journal of Orthodontics. 38 (3): 237–50. doi:10.1093/ejo/cjv048. PMC 4914905. PMID 26136439.
- Cambiano AO, Janson G, Lorenzoni DC, Garib DG, Dávalos DT (2018). "Nonsurgical treatment and stability of an adult with a severe anterior open-bite malocclusion". Journal of Orthodontic Science. 7: 2. doi:10.4103/jos.JOS_69_17. PMC 5952238. PMID 29765914.
- "Angle's Classification of Malocclusion". Archived from the original on 2008-02-13. Retrieved 2007-10-31.
- Sunil Kumar (Ed.): Orthodontics. New Delhi 2008, 624 p., ISBN 978-81-312-1054-3, p. 127
- Sunil Kumar (Ed.): Orthodontics. New Delhi 2008, p. 123. A list of 18 approaches to modify or replace Angle's system is given here with further references at the end of the book.
- Gurkeerat Singh: Textbook of Orthodontics, p. 163-170, with further references on p. 174.
- Lieberman DE, Krovitz GE, Yates FW, Devlin M, St Claire M (June 2004). "Effects of food processing on masticatory strain and craniofacial growth in a retrognathic face" (PDF). Journal of Human Evolution. 46 (6): 655–77. doi:10.1016/j.jhevol.2004.03.005. PMID 15183669. Archived from the original (PDF) on 2012-02-06.
- Ingervall B, Bitsanis E (February 1987). "A pilot study of the effect of masticatory muscle training on facial growth in long-face children" (PDF). European Journal of Orthodontics. 9 (1): 15–23. doi:10.1093/ejo/9.1.15. PMID 3470182.
- Rosenberg J (2010-02-22). "Malocclusion of teeth". Medline Plus. Retrieved 2012-02-06.
- von Cramon-Taubadel N (December 2011). "Global human mandibular variation reflects differences in agricultural and hunter-gatherer subsistence strategies". Proceedings of the National Academy of Sciences of the United States of America. 108 (49): 19546–51. Bibcode:2011PNAS..10819546V. doi:10.1073/pnas.1113050108. PMC 3241821. PMID 22106280. Lay summary.
- Pinhasi R, Eshed V, von Cramon-Taubadel N (2015). "Incongruity between affinity patterns based on mandibular and lower dental dimensions following the transition to agriculture in the Near East, Anatolia and Europe". PLOS ONE. 10 (2): e0117301. Bibcode:2015PLoSO..1017301P. doi:10.1371/journal.pone.0117301. PMC 4317182. PMID 25651540.
- Batista KB, Thiruvenkatachari B, Harrison JE, O'Brien KD (March 2018). "Orthodontic treatment for prominent upper front teeth (Class II malocclusion) in children and adolescents". The Cochrane Database of Systematic Reviews. 3: CD003452. doi:10.1002/14651858.cd003452.pub4. PMC 6494411. PMID 29534303.
- Grauer D, Heymann GC, Swift EJ (June 2012). "Clinical management of tooth size discrepancies". Journal of Esthetic and Restorative Dentistry. 24 (3): 155–9. doi:10.1111/j.1708-8240.2012.00520.x. PMID 22691075.
- Bugaighis I, Karanth D, Borzabadi-Farahani A (February 2015). "Tooth size discrepancy in a Libyan population, a cross-sectional study in schoolchildren". Journal of Clinical and Experimental Dentistry. 7 (1): e100–5. doi:10.4317/jced.51819. PMC 4367995. PMID 25810819.
- Posnick JC (September 2013). "Definition and Prevalence of Dentofacial Deformities". Orthognatic Surgery: Principles and Practice. Amsterdam: Elsevier. pp. 61–68. doi:10.1016/B978-1-4557-2698-1.00003-4. ISBN 978-145572698-1.
- Harrington C, Gallagher JR, Borzabadi-Farahani A (July 2015). "A retrospective analysis of dentofacial deformities and orthognathic surgeries using the index of orthognathic functional treatment need (IOFTN)". International Journal of Pediatric Otorhinolaryngology. 79 (7): 1063–6. doi:10.1016/j.ijporl.2015.04.027. PMID 25957779.
- Borzabadi-Farahani A, Eslamipour F, Shahmoradi M (June 2016). "Functional needs of subjects with dentofacial deformities: A study using the index of orthognathic functional treatment need (IOFTN)". Journal of Plastic, Reconstructive & Aesthetic Surgery. 69 (6): 796–801. doi:10.1016/j.bjps.2016.03.008. PMID 27068664.
- Klein ET (1952). "Pressure Habits, Etiological Factors in Malocclusion". Am. J. Orthod. 38 (8): 569–587. doi:10.1016/0002-9416(52)90025-0.
- Graber TM. (1963). "The "Three m's": Muscles, Malformation and Malocclusion". Am. J. Orthod. 49 (6): 418–450. doi:10.1016/0002-9416(63)90167-2.
- Björk A, Helm S (April 1967). "Prediction of the age of maximum puberal growth in body height" (PDF). The Angle Orthodontist. 37 (2): 134–43. doi:10.1043/0003-3219(1967)037<0134:POTAOM>2.0.CO;2 (inactive 2019-06-29). PMID 4290545.
- Brucker M (1943). "Studies on the Incidence and Cause of Dental Defects in Children: IV. Malocclusion" (PDF). J Dent Res. 22 (4): 315–321. doi:10.1177/00220345430220041201.
- Calisti LJ, Cohen MM, Fales MH (1960). "Correlation between malocclusion, oral habits, and socio-economic level of preschool children". Journal of Dental Research. 39 (3): 450–4. doi:10.1177/00220345600390030501. PMID 13806967.
- Subtelny JD, Subtelny JD (October 1973). "Oral habits--studies in form, function, and therapy". The Angle Orthodontist. 43 (4): 349–83. PMID 4583311.
- Aznar T, Galán AF, Marín I, Domínguez A (May 2006). "Dental arch diameters and relationships to oral habits". The Angle Orthodontist. 76 (3): 441–5. doi:10.1043/0003-3219(2006)076[0441:DADART]2.0.CO;2 (inactive 2019-06-29). PMID 16637724.
- Yamaguchi H, Sueishi K (May 2003). "Malocclusion associated with abnormal posture". The Bulletin of Tokyo Dental College. 44 (2): 43–54. doi:10.2209/tdcpublication.44.43. PMID 12956088.
- Wellington M, Hall CB (February 2002). "Pacifier as a risk factor for acute otitis media". Pediatrics. 109 (2): 351–2, author reply 353. doi:10.1542/peds.109.2.351. PMID 11826228.
- Rovers MM, Numans ME, Langenbach E, Grobbee DE, Verheij TJ, Schilder AG (August 2008). "Is pacifier use a risk factor for acute otitis media? A dynamic cohort study". Family Practice. 25 (4): 233–6. doi:10.1093/fampra/cmn030. PMID 18562333.
- Hamish T (1990). Occlusion. Parkins, B. J. (2nd ed.). London: Wright. ISBN 978-0723620754. OCLC 21226656.