Advanced surgery I Anatomy Sinus lift techniques Complications Theodora Kompotiati 09/23/2014
Anatomy of the maxillary sinus
Development of the maxillary sinus • Begins to form in the fetus • By 5 months has the size of a pea • Reaches adult size by 12-14 years • Roots of max premolars and molars in close proximity to the sinus • Roots of 2 nd molar nearest to the sinus cavity (then those of 1 st and 3 rd molars)
Maxillary sinus • Laterally directed pyramid, 25-35mm width 36-45mm height 38-45mm length • Average volume 15-20 ml • Ostium- average diameter 2.4mm (1-17mm) Surgical complications in oral implantology, Quintessence 2011, Van den Bergh 2000
Osteomeatal complex A channel that links • the frontal sinus, ethmoid sinuses and maxillary sinus to the middle meatus that allows air flow and drainage Obstruction=infection •
Anterior wall • Cortical bone extending from the orbital rim to just above the apex of the cuspid • Infraorbital foramen (6-7mm below the orbital rim) • Be aware of the foramen when retracting the flap, no need for very high window preparations
Posterior wall Corresponds to pterygomaxillary • region which separates the antrum from the infratemporalfossa Vital structures: internal maxillary • artery pterygoid plexus, sphenopalatineganglion and greater palatine nerve. Should always be identified in • radiograph !!! Lack of posterior wall, pathologic • condition should be suspected
Superior wall • Shared with the thin orbital floor • Bony bridge present that houses the infraorbital canal ( infraorbital nerve and vessels) Dehiscence may be present resulting in direct contact between infraorbital structures and sinus mucosa Sinus infections or neoplasms Proptosis, diplopia
Inferior wall • Floor of the maxillary sinus • Close relationship with apices of premolars and maxillary molars • In dentate patients the floor is approximately at the level of the nasal floor • In edentulous posterior maxilla the sinus floor is 1cm below the level of the nasal floor
Medial wall • Coincides with lateral wall of the nasal cavity • In the superior aspect the ostium is located • Ostium diameter in health averages 2.4mm. Pathology 1-17mm
Lateral wall • Posterior maxilla and zygomatic process • Thickness varies from several mm in a dentate patient to less than 1mm in an edentulous patient
Blood supply • Maxilla is densely vascularized in young and dentate patients • Blood supply to bone is permanently reduced with age, progressing atrophy and decrease in number and diameter of blood vessels
Blood supply • Branches of maxillary artery Ø Infraorbital artery (IOA) Ø Posterior superior alveolar artery ( PSAA)
Solar,1999 • 18 max segments, human cadavers • Extraosseous anastomosis v 8/18 of the specimens (44.4%) v 23-26mm from the alveolar margin • Intraosseous anastomosis v 100% v 18.9-19.6 from the alveolar margin
Schneiderian membrane Blood supply • PSAA • IAO • Intraosseous anastomosis of PSAA and IAO • Sphenopalatine artery Vascularization of the graft material into the sinus • Intraosseous anastomosis • Extraosseous anastomosis • Vessels of the Schneiderian membrane
Innervation of maxillary sinus • Maxillary nerve V2 (sensory) Sensation to skin of midface, nasal and palatal mucosa, upper teeth and gingiva, lower eyelid
Branches of maxillary nerve • Posterior, middle, anterior superior alveolar nerve • Greater palatine nerve • Infraorbital nerve
Septa • First described by the anatomist Underwood in 1910 • Known as Underwood’s septa • Presence of septa can cause complications during sinus elevation procedures
Ulm et al, 1995 • 41 edentulous maxillae • Only lamellae ≥2.5mm in height considered septa • Sinus floor with at least 1 septum – 31.7% • 1 septum- 26.8%, 2 septa- 4.9% • 73.7% in anterior region (premolar), 19.9% in middle (1 st molar)and 6.6% in posterior (2 nd molar) • Mean height 7.9mm (highest 17mm) • No correlation with residual bone height and incidence of septa
Pommer et al, 2012 Systematic review • 33 studies • Sinus septa prevalence- • 28.4% 17.2% had bilateral septa • 2 septa in same sinus-3.7% • 3 septa in same sinus-0.5% 54.6% located at 1 st and 2 nd molar region • mean height 7.5mm • 99.7% of septa were incomplete • Orientation (buccopalatal87.6%, mesiodistal 11.1%, parallel to sinus floor • 1.3%) septa prevalence significantly lower in Asian population • Septa prevalence significantly higher in edentulous ridges • !!!!Diagnosis of sinus septa in PAN –incorrect results is • 29%
Maxillary Sinus Septa: Prevalence, Height, Location, and Morphology. A Reformatted Computed Tomography Scan Analysis v Prevalence of one or more septa per sinus 26.5% in the overall study population § 31.76% in the atrophic/edentulous maxilla § 22.61% in the non-atrophic/dentate § maxillary segments v Anatomic location: 25.4% were located in the anterior region § 50.8% in the middle region § 23.7% in the posterior region § Height of the septa varied among the v different areas 1.63– 2.44mm lateral area § 3.55– 2.58mm middle area § 5.46– 3.09mm medial area § Kim et al 2006
Sinus membrane Epithelial cells are a continuation of • the nasal mucosa Pseudostratified, ciliated, columnar • epithelium 5 types of cells: 1)ciliated columnar • 2)non ciliated columnar 3) basal cells 4) goblet cells and 5) seromucinous cell Ciliated cells contain 50 to 200 cilia • per cell- help clear mucus Goblet cells produce glycoproteins- • viscosity and elasticity of the mucus produced Thickness of membrane: 0.3-0.8mm •
Maxillary sinus bacterial flora • Normal sinuses- non sterile • 62.3% exhibited bacterial colonization ² Strep viridans ² Staph epidermidis ² Strep pneumoniae • Culture findings from secretions in acute sinusitis ² Strep pneumoniae ² Strep pyogenes ² Haemophilus influenza Misch, 3 rd edition
CT SCAN • Air: black (radiolucent) • Bone: white (radiopaque) • Fluid: varying degrees of gray • Sinus membrane: Normal-invisible Inflamed- varying degrees of gray
CT SCAN • First thing we look is if the ostium is patent
Anatomical variants • Skeletal and bony abnormalities may compromise the patency of the ostium and cause post-operative complications
Nasal septum deviation • 70% of the population over 14 years old • Extreme cases may obstruct the osteomeatal unit and increase the risk of sinusitis after graft
Middle turbinate variants Middle turbinate: • significant role in proper drainange of maxillary sinus Concha bullosa: • pneumatization within the middle turbinate, may occlude osteomeatal complex (4-15% of the population) Paradoxically curved • middle turbinate: concavity towards the septum, decreasing the size of meatus
Deflected uncinate process
Big nose variant Inferior turbinate • and meatus pneumatization 3% incidence • If unaware the • implants can be placed into the nasal cavity !!!Sinus graft is • contraindicated
Pre-operative sinus pathology • Acute sinusitis • Chronic sinusitis • Fungal sinusitis • Cystic stractures and mucoceles • Neoplasms
Acute Sinusitis • Haemophilus influenza, Moraxella catarhallis, Streptococcus preumoniae • Fever, foul rhinorrhea or postnasal drainage, facial pain/swelling • Dental pain is common (sinus proximity) !!!! Sinus surgery is strongly contraindicated
Radiographic appearance • Air-fluid level • If patient is supine the fluid will accumulate in posterior area • Thickening of membrane • Severe conditions- sinus appears completely opacified
Acute bacterial sinusitis Amoxicillin 500mg tid 10-14 days Acute bacterial sinusitis with Trimethoprim- 1 double-strength allergy to pen sulfamethoxazole tablet(160/800mg) bid 10-14 or days Azithromycin 500mg once daily 7-10days Clarithromycin 500mg bid 10-14 days Acute bacterial sinusitis with Amoxicillin-clavulanate 875 mg bid 14-21days antibiotic use in the past 4-6 weeks (or failure of the or above meds) Fluoroquinolone: Ciprofloxacin 750mg bid 10-14 days Levofloxacin 500mg once daily 10-14days Moxifloxacin 400mg once daily 10-14days Acute bacterial sinusitis with Clindamycin 300mg qid 14-21 days suspected odontogenic origin of Metronidazole 500mg bid 14-21 days Al-Faraje 2011
Chronic sinusitis Not infection, chronic inflammation • Diagnosis: pt must have had symptoms for at • least 12 weeks Congestion, nasal obstruction, sinus pressure, • postnasal drainage, fatigue, decreased sense of smell CT: mucosal thickening or sinus opacification • Anterior rhinoscopy: swelling, thick drainage, • polyps !!!sinus augmentation will not initiate chronic • sinusitis, it may exacerbate the condition
Recommended treatment • Corticosteroids • Antihistamines • Decongestants • Leukotriene blockers • Antibiotics (when bacterial infection occurs) If medical therapy fails, ESS (endoscopic sinus surgery) may be required.
Fungal sinusitis • Fungal ball • Allergic fungal rhinosinusitis • Invasive fungal sinusitis
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