Human health and medicine

Oral Surgical Procedures

Oral surgical procedures (MeSH D019647) are operations inside the mouth and maxillofacial region: extractions, third molar surgery, implants, bone and gum grafts, orthognathic and preprosthetic surgery, distinguished from broader maxillofacial surgery.

Oral trivalent reassortant rotavirus live attenuated vaccine (Vero cell), LLR3

LLR3 (Reassortant Rotavirus Vaccine, Live, Oral, Trivalent, Vero Cell) is a Chinese human-lamb reassortant rotavirus vaccine covering G2, G3, G4, licensed April 2023 by Lanzhou Institute of Biological Products, with 56.6% efficacy against any-severity rotavirus gastroenteritis.

ORAL1069 trial

ORAL1069 (Pfizer protocol A3921069), also called ORAL Start, is a 24-month phase 3 trial (NCT01039688) showing tofacitinib monotherapy superior to methotrexate in methotrexate-naïve rheumatoid arthritis, with higher zoster and cancer rates.

ORANGE study

The ORANGE study was a 2023 multicenter cohort study of 514 ICU patients showing that automated pupillometry, the Neurological Pupil index, predicts outcome after severe acute brain injury.

Orantinib

Orantinib (SU6668, TSU-68) is an investigational anticancer drug, an orally bioavailable tyrosine kinase inhibitor blocking VEGFR2, PDGFR, and FGFR, developed by Sugen and never approved.

ORARAD study

ORARAD (Clinical Registry of Dental Outcomes in Head and Neck Cancer Patients, NCT02057510) is a NIDCR-funded, six-site US prospective cohort of 572 head and neck cancer radiotherapy patients, reporting 17.7% two-year tooth failure, 3.1% confirmed osteoradionecrosis, and post-RT caries increment.

Orbicularis oculi muscle

Orbicularis oculi: sphincter-like facial muscle around the eyelids that closes the eye, aids tear drainage, divides into orbital, preseptal, and pretarsal parts, and is innervated by CN VII.

Orbit (anatomy)

Orbit (anatomy): the bony eye socket, formed by seven skull bones (frontal, ethmoid, lacrimal, palatine, maxillary, zygomatic, sphenoid), housing the globe, optic nerve, and extraocular muscles, with optic canal and orbital fissures.

ORBIT II trial

ORBIT II (Evaluate the Safety and Efficacy of OAS in Treating Severely Calcified Coronary Lesions) was a 443-patient, 49-site U.S. single-arm pivotal trial of the Diamondback 360 orbital atherectomy system for severely calcified coronary lesions, meeting safety (89.6% freedom from 30-day MACE) and efficacy (88.9% procedural success) endpoints and supporting FDA approval in 2013.

ORBIT-SHOCK trial

ORBIT-SHOCK (NCT06736665) is a Spanish Society of Cardiology randomized pilot trial of 50 patients comparing orbital atherectomy with intravascular lithotripsy for OCT-identified calcified coronary nodules, with OCT-measured stent expansion as the primary endpoint.

Orbital abscess

Orbital abscess, Chandler group IV orbital infection, is a pus collection within the orbit, usually from ethmoid sinusitis spread, causing proptosis and vision loss; treated with IV antibiotics and often surgical drainage.

Sep 29, 2026

Orbital atherectomy

Orbital atherectomy is a catheter-based procedure in which a diamond-coated crown orbiting inside an artery sands away severely calcified plaque to enlarge the lumen and ease stent delivery.

Orbital cellulitis

Orbital cellulitis (postseptal cellulitis) is infection of the eye socket tissues behind the orbital septum, usually spreading from ethmoid or other paranasal sinusitis. Distinct from preseptal cellulitis; treated with IV antibiotics and surgery, it threatens vision and can cause cavernous sinus thrombosis.

Orbital cyst

Orbital cyst (ICD-11 9A23): an epithelium- or tissue-lined cystic lesion in the orbit, congenital or acquired. Dermoid cysts dominate, 3-9% of orbital masses; diagnosis by CT/MRI, treatment by intact excision.

Sep 29, 2026

Orbital floor reconstruction

Orbital floor reconstruction is a surgical procedure that repairs defects in the bony floor of the eye socket, repositioning herniated contents and placing an implant or graft.

Orbital fracture

Orbital fracture, including blowout fracture of the orbital floor or medial wall: break in the eye socket bones from blunt trauma, causing diplopia, enophthalmos, and V2 numbness; diagnosed by thin-cut CT, managed observationally or surgically.

Orbital Implants

Orbital implants are devices placed in the socket after eye removal (enucleation, evisceration) to restore volume; porous types include hydroxyapatite, Medpor polyethylene, and aluminum oxide, versus nonporous PMMA and silicone.

Orbital infection

Orbital infection, chiefly orbital cellulitis, is infection of tissues behind the orbital septum, usually spreading from ethmoid sinusitis. Incidence 1.6/100,000 children; staged by Chandler classification; treated with IV antibiotics and sometimes drainage.

Orbital inflammation

Orbital inflammation (nonspecific orbital inflammation, idiopathic orbital inflammation, orbital pseudotumor) is benign noninfectious inflammation of orbital tissues, diagnosed by exclusion, third commonest after thyroid eye disease and lymphoma, treated first with corticosteroids.

Orbital leiomyoma

Orbital leiomyoma (ORPHA:52994) is a rare benign smooth muscle tumor of the eye socket, arising from orbital vessel walls or Müller's muscle, slow-growing, encapsulated, causing painless proptosis, treated by complete excision with excellent prognosis.

Orbital subperiosteal abscess

Orbital subperiosteal abscess (SPA), Chandler stage III orbital infection: pus between the orbital wall and periorbita, usually medial, complicating ethmoid or frontal sinusitis; managed medically in selected young patients, drained otherwise.

Orbitofrontal cortex

Orbitofrontal cortex (OFC), ventral prefrontal cortex above the eyes; areas 11, 13, 14, 47/12; represents reward value and hedonic experience, supports decision making; damage causes impulsive, socially inappropriate behavior.

Sep 29, 2026

Orchidopexy

Orchidopexy (or orchiopexy) is a surgical operation that moves an undescended testicle into the scrotum and fixes it there, the standard treatment for cryptorchidism in pediatric urology, ideally performed between 6 and 18 months of age.

Orchiectomy

Orchiectomy, also spelled orchidectomy, is surgery to remove one or both testicles. It treats testicular and prostate cancer, removes damaged testicles, and serves as a gender-affirming procedure.

Orchiopexy

Orchiopexy (orchidopexy) is surgery that moves an undescended testis into the scrotum, the standard treatment for cryptorchidism, recommended between 6 and 18 months of age; also fixes the testis after torsion. First successful operation by Thomas Annandale, 1877.

Orchitis or epididymitis

Orchitis or epididymitis (epididymo-orchitis) is inflammation of the testis, epididymis, or both, usually from STIs in younger men, enteric bacteria in older men, or mumps virus; treated with ceftriaxone, doxycycline, or fluoroquinolones.

Oregovomab

Oregovomab (OvaRex, MAb B43.13), a murine anti-CA-125 monoclonal antibody immunotherapy for ovarian cancer; failed phase III maintenance monotherapy, now tested with paclitaxel-carboplatin in FLORA-5.

Orexin

Orexin (hypocretin): hypothalamic neuropeptide pair orexin-A/B that stabilizes wakefulness and suppresses REM; its loss causes narcolepsy type 1, and its receptors are drug targets for insomnia antagonists and 2026-approved narcolepsy agonists like oveporexton.

Orforglipron

Orforglipron (Foundayo) is Eli Lilly's once-daily oral, non-peptide GLP-1 receptor agonist, discovered by Chugai and FDA-approved April 1, 2026 for weight management; doses up to 17.2 mg, no food or water restrictions, half-life 29-49 hours.