All articles starting with O

Oradea

Oradea (Nagyvárad, Großwardein) is a municipality in north-western Romania, seat of Bihor County, first recorded in 1113 as Civitas Varadiensis, known for Art Nouveau architecture and a medieval fortress.

Oradea Zoological Garden

Oradea Zoological Garden (Grădina Zoologică Oradea, Zoo Oradea) is a municipal zoo in Oradea, Romania, founded 1960, reopened 2013 after modernization, holding 650+ animals of 140+ species, now being relocated to Sânmartin.

Oradour-sur-Glane massacre

Oradour-sur-Glane massacre: 10 June 1944 killing of 642 villagers by the Waffen-SS Division Das Reich's Der Führer regiment, men shot in barns, women and children burned in the church; ruins kept as a French national memorial.

Oct 22, 2026

Oraga Haru

Oraga Haru (おらが春, "My Spring") is a haibun collection by the Japanese poet Kobayashi Issa, recording 1819 and centering on the death of his infant daughter Sato.

Sep 21, 2026

Orah S. Platt

Orah S. Platt is a professor of pediatrics at Harvard Medical School based at Boston Children's Hospital, known for her landmark studies of pain and mortality in sickle cell disease.

Orai

Orai (उरई) is a city in Uttar Pradesh, India, headquarters of Jalaun district in Bundelkhand on the Kanpur-Jhansi NH27; 2011 population 190,595, third largest city of Jhansi division.

Oct 20, 2026

ORAI1

ORAI1 (CRACM1, formerly TMEM142A), gene at 12q24.31 encoding the pore-forming subunit of STIM1-gated CRAC calcium channels; loss-of-function causes combined immunodeficiency, gain-of-function causes tubular aggregate myopathy and Stormorken syndrome.

Oral administration

Oral administration (per os) is giving drugs by way of the mouth, the most convenient and widely used route. Key facts: lower bioavailability than IV due to first-pass metabolism; Spansule 1952 began oral controlled release; food effects and poor solubility limit it.

Oral allergy syndrome

Oral allergy syndrome, also called pollen-food allergy syndrome (PFAS), is an IgE-mediated cross-reaction between pollen and plant foods causing itchy, swollen mouth and throat, usually mild, rarely anaphylactic, managed by avoiding raw foods.

Oral and maxillofacial surgery

Oral and maxillofacial surgery (OMFS, OMS) is the surgical specialty treating diseases, injuries, and defects of the mouth, jaws, and face, bridging dentistry and medicine through single or dual degree training pathways worldwide.

Oral appliance therapy

Oral appliance therapy (OAT) is a dental treatment for obstructive sleep apnea and snoring in which a removable device worn during sleep holds the lower jaw forward to keep the airway open.

Oral argument before the United States Supreme Court

Oral argument before the United States Supreme Court is the courtroom session where lawyers for each side answer the justices' questions before the Court decides a case.

Oral cancer

Oral cancer: squamous cell carcinoma of the lips and mouth (oral cavity), related to HPV-driven oropharyngeal cancer. Key facts: tobacco, alcohol, betel quid, HPV-16; 389,846 global cases 2022; 69% US 5-year survival.

Oral candidiasis

Oral candidiasis (thrush), Candida albicans overgrowth of the oral mucosa; occurs with dentures, antibiotics, steroids, diabetes, HIV; treated with topical nystatin, clotrimazole, miconazole, or oral fluconazole for 7-14 days.

Oral Diagnosis

Oral diagnosis: dental specialty of identifying oral diseases via history, conventional oral examination (visual inspection and palpation), radiographs, and biopsy. COE shows 71-88% sensitivity for oral cancer; biopsy is definitive.

Oral diseases

Oral Diseases (Oral Dis) is a Wiley peer-reviewed journal of oral medicine and head and neck disorders, founded 1995, ISSNs 1354-523X and 1601-0825, edited by Giovanni Lodi.

Oral fibroepithelial polyp

The oral fibroepithelial polyp, also known as an irritation fibroma, is a common benign growth of fibrous tissue in the mouth, usually caused by cheek biting or dentures.

Oral food challenge

An oral food challenge is a medical test in which a patient eats increasing amounts of a suspected food under supervision to confirm or rule out a food allergy.

Oral hexavalent reassortant rotavirus live attenuated vaccine (Vero cell)

Oral hexavalent reassortant rotavirus live attenuated vaccine (Vero cell), brand 武生儿轮宝: Wuhan Institute of Biological Products' oral live vaccine against rotavirus G1, G2, G3, G4, G8, G9 in infants 6–36 weeks; NMPA-approved August 2025, first hexavalent rotavirus vaccine globally.

Oral history

Oral history: the recording, preservation, and interpretation of spoken interviews about the past, founded as a systematic method by Allan Nevins at Columbia in 1948, governed by Oral History Association standards on consent, interviewing, archiving, and memory as evidence.

Oral hygiene

Oral hygiene: daily cleaning of the mouth by brushing with fluoride toothpaste, flossing, and limiting sugar to prevent cavities and gum disease; tools from Babylonian chew sticks to the Tang-dynasty toothbrush and modern fluoride products.

Oral hygiene index

The Oral Hygiene Index (OHI) is a clinical dental index introduced by Greene and Vermillion in 1960 that scores debris and calculus on tooth surfaces, giving a total from 0 to 12.

Oral immunotherapy

Oral immunotherapy (OIT) is an allergy treatment in which gradually increasing swallowed doses of a food allergen raise the reaction threshold, protecting against accidental exposure while daily dosing continues.

Oral literature

Oral literature, also called orature (Pio Zirimu, 1977), is verbal art such as epic, tales, proverbs, and song produced, transmitted, or performed without writing; studied via Parry-Lord oral-formulaic theory and Vansina's methods, and safeguarded by UNESCO as intangible heritage.

Oral Medicine

Oral medicine, also called stomatology, is the dental specialty diagnosing and nonsurgically managing oral, facial, and jaw disorders and oral manifestations of systemic disease; founded 1925, US specialty recognition 2020.

Oral mucocele

Oral mucocele (mucous cyst, ranula when on the floor of the mouth): benign mucus-filled cyst of minor salivary glands, usually on the lower lip, caused by trauma; extravasation and retention types; often self-healing.

Oral mucosa

The oral mucosa, also called the mouth mucosa, is the moist tissue lining the inside of the mouth, protecting it from mechanical, chemical, thermal, and microbial damage.

Oral mucositis

Oral mucositis: painful inflammation and ulceration of the mouth lining caused by chemotherapy and radiotherapy, affecting 40-80% of chemotherapy patients, with five-phase pathobiology and MASCC/ISOO guidelines.

Oral Pathology

Oral pathology, in its modern form called oral and maxillofacial pathology, is the dental specialty diagnosing diseases of the mouth and jaws through biopsy-based histopathology.