Class I (Neutrocclusion): Here the molar relationship of the occlusion is normal but the incorrect line of occlusion 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 Angles system of classes and alternative systems
A major disadvantage of Angles system of classifying malocclusions is that it only considers two dimensions along a spatial axis in the sagittal plane in the terminal occlusion, but occlusion problems can be three-dimensional.
Gallbladder and sphincter of Oddi disorders

E1. Biliary pain
E1a. Functional gallbladder disorder
E1b. Functional biliary sphincter of Oddi disorder
E2. Functional pancreatic sphincter of Oddi disorderF. Anorectal disorders

F1. Fecal incontinence
F2. Functional anorectal pain
F2a. Levator ani syndrome
F2b. Unspecified functional anorectal pain
F2c. Proctalgia fugax
F3. Functional defecation disorders
F3a. Inadequate defecatory propulsion
F3b. Dyssynergic defecationG. Childhood functional GI disorders: Neonate/Toddler

G1. Infant regurgitation
G2. Rumination syndrome
G3. Cyclic vomiting syndrome (CVS)
G4. Infant colic
G5. Functional diarrhea
G6. Infant dyschezia
G7. Functional constipationH. Childhood functional GI disorders: Child/Adolescent

H1. Functional nausea and vomiting disorders
H1a. Cyclic vomiting syndrome (CVS)
H1b. Functional nausea and functional vomiting
H1b1. Functional nausea
H1b2. Functional vomiting
H1c. Rumination syndrome
H1d. Aerophagia
H2. Functional abdominal pain disorders
H2a. Functional dyspepsia
H2a1. Postprandial distress syndrome
H2a2. Epigastric pain syndrome
H2b. Irritable bowel syndrome (IBS)
H2c. Abdominal migraine
H2d. Functional abdominal pain ‒ NOS
H3. Functional defecation disorders
H3a. Functional constipation
H3b. Nonretentive fecal incontinence

Epidemiology
Functional gastrointestinal disorders are very common. Globally, irritable bowel syndrome and functional dyspepsia alone may affect 16–26% of the population. Research
There is considerable research into the causes, diagnosis and treatments for FGIDs. Diet, microbiome, genetics, neuromuscular function and immunological response all interact. A role for mast cell activation has been proposed as one of the factors. See also
Allergy
Food intolerance
Functional indigestion
Histamine intolerance

References


== External links ==