Title: Dental crowding Content: thumb|Mild crowding with deep bite Dental crowding is the situation when the teeth are positioned as crowded in the oral cavity due to lack of space. It is the most common dental malocclusion. Archeological evidences shows that dental crowding is a result of refinement in the diet pattern over thousand of years. Dental crowding can be seen in one arch or both the arches. It can be mild, moderate or severe based on the space requirements. == History == Crowding is much more prevalent in modern populations than it was in prehistoric times. The studies of skeletons from Ancient Egypt and Sudan shows that crowding was not quite prevalent in ancient times. Some investigators have attributed this problem to the change in diet such as processed food or introduction of cutlery and chopsticks. Treatment involving teeth removal were carried out to relieve crowding and French dentists, Bunon and Bourdet were among the pioneer dentists of modern times to extract teeth to correct crowding. In 1929 Kjellegren suggested extractions of teeth including milk teeth in a pattern called serial extraction. After orthodontics became a specialty in dentistry various methods of correction of crowding were done and published. Raymond P. Begg who was a pioneer Australian orthodontist almost always practiced extractions of premolar in his treatment regime Other methods of corrections of crowding include arch expansion, Inter proximal reduction of tooth ( stripping). == Reasons == Various reasons have been attributed to the problem of dental crowding. The basic reason is the mismatch of width of teeth and the length of the basal bone where teeth are situated.Plavcan JM, Daejling DJ. Interspecific and intraspecific relationships between tooth size and jaw size in primates. Journal of Human Evolution. 2006;51(2):171–84. Genetic and environmental factors have been identified but what causes the over crowding still remains unclear. == Classifications == Dental crowding can be classified based on the jaws as maxillary or mandibular crowding or bimaxillary crowding and based on the time of occurance as primary, secondary and teritiary or late crowding . It can also be classified based on the space requirement as mild (1-4 mm), )moderate ( 4-8mm) and severe ( more than 8 mm) https://codental.uobaghdad.edu.iq/wp- content/uploads/sites/14/2020/03/L1-Crowding-2020.pdf ====== Primary crowding ====== It is a hereditary type of crowding and is determined genetically. presents with disproportionately sized teeth and jaws. Crowding of anterior teeth is characteristic of this type of crowding. ==== Secondary crowding ==== It is an acquired form of maloclusion which happens due to premature loss of deciduous teeth and resultant migration of permanent teeth in to such gaps. ==== Teritiary Crowding ==== This type of crowding happens in later life. This crowding appears or worsens the already present crowding situations. Reasons are believed to be the pressure from the erupting third molars. But it also occurs in patient with congenitally missing third molars.Proffit, W.R., Fields, H.W. and Sarver, D.M. (2007) Treatment of Skeletal Problems in Children. Contemporary Orthodontics. 4th Edition, Eldsevier Mosbey, St Louis, 495-496. == Prevalence == It affects 60% of Caucasians. Studies have shown that the people in South Africa had the least crowding. Samples from United States exhibited minor dental crowding. American Blacks had lower crowding levels, while the Indigenous group of America had high levels of severe crowding. Individuals within China and Japan exhibited higher relative prevalence of severe crowding. == Prediction of crowding == Prediction of future crowding can be done by methods proposed by various investigators such as Moyers,Galvão, Mariana de Aguiar Bulhões; Dominguez, Gladys Cristina; Tormin, Sérgio Thomaz; Akamine, Alex; Tortamano, André; Fantini, Solange Mongelli de (2013). "Applicability of Moyers analysis in mixed dentition: A systematic review". Dental Press Journal of Orthodontics. 18 (6): 100–105. doi:10.1590/S2176-94512013000600015. ISSN 2176-9451. PMID 24351156. PontsMühlberg G, Nedelko U, Weiskopf J. Zur kritischen Bewertung des Pontschen Indexes unter Berücksichtigung des Einflusses der mesio-distalen Distanz der Seitenzahngruppe. Biologisch-statistische Untersuchungen an 417 eugnathen Gebissen [Evaluation of Pont's index with speical reference to the mesiodistal distance of the lateral teeth. Statistical analysis of 417 eugnathic dentitions]. Dtsch Stomatol. 1969 Oct;19(10):775-83. German. PMID: 5262916. Linder Harth and Tanaka and Johnston. Predictions cane be based on the size of the lower incisors or based on the orthopantomograph. == Treatments == Treatment of crowded teeth is done by orthodontics after gaining spaces needed to arrange the crowded teeth. These treatments are either removable using traditional acrylic appliances or modern clear aligner theray or fixed type using attachements bonded to the teeth, labially or lingually. === Methods of space gaining === There are 3 methods of treating dental crowding. 1) Dental arch expansion 2) Inter proximal reduction ( IPR) or slenderizing the teeth 3) Extraction of 1 or more teeth. Using these methods of space gaining in the dental arch, treatments such as removable or fixed orthodontic treatments are carried out to position the teeth in alignment. ==== Dental Arch expansions ==== thumb|Hyrax rapid palatal expander Narrowed dental arch can be successfully expanded. There are slow expanders such as removable jack screw appliancesHicks EP. Slow maxillary expansion. A clinical study of the skeletal versus dental response to low-magnitude force. Am J Orthod. 1978 Feb;73 and fast expanders such as HyraxBishara SE, Staley RN. Maxillary expansion: clinical implications. Am J Orthod Dentofacial Orthop. 1987 Jan;91(1):3–14. and surgically assisted rapid maxillary expansions (SARPE). Slow expansion causes dental expansionMajourau A, Nanda R. Biomechanical basis of vertical dimension control during rapid palatal expansion therapy. Am. J Orthod Dentofacial Orthop. 1994 Sep;106(3):322–328. while rapid expansions causes skeletal changes in the mid palatine suture of the maxillary bone.Haas AJ. Rapid expansion ofthe maxillary dental arch and nasal cavity by opening the midpalatal suture. Angle Orthod. 1961;31:73–90. Expansions of the dental arch gains space which can be utilized by further orthodontic treatments. ==== Inter Proximal Reduction ==== thumb|Abrasive disk used for IPR Also known as IPR or stripping or slenderization, this methods shortens the width or one or more teeth in the oral cavity to create space for alignment of other teeth. Abrasive strips, disks or burs coupled with high speed airotor turbineSheridan J. J. Air-rotor-stripping. J Clin Orthod 1985 19:43–59. are used to create space. Various authors suggest different amounts of enamel reduction. Fillion, D.Vor- und Nachteile der approximalen Schmelzreduktion. Inf Orthod Kieferorthop 1995. 27;64–90. Maximum of 9.8 mm space have been successfully created by IPR. ==== Extractions of teeth ==== Extractions of teeth have been done traditionally to create space for problems such as crowding and protrustion. The most common teeth to be extracted is the first premolar followed by second premolar. In rare cases lower incisors and first molars are also extracted to create space or balance in the occlusion.Basciftci FA, Usumez S. Effects of extraction and nonextraction treatment on class I and class II subjects. Angle Orthod. 2003;73:36–42.