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* What functional morbidities result if a large maxillary defect is not obturated effectively?
- -speech is hypernasal
- -leakage of food/fluid into nasal passage
- -Mastication efficacy is decreased (tongue is preoccupied with keeping obturator in position)
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* When a large maxillary defect is anticipated secondary to resection of a large tumor, several alterations at surgery are suggested that will enhance the prosthetic rehabilitation. List the three most important and why, in each case they are important?
- - skin grafting the defect: enhances retention
- - maintain access to the defect
- - salvaging the premaxillary segment: enhances support (palatal shelf), stability, and additional implant sites.
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* It is now possible to close large maxillary defects with free vascularized flaps. Why is this practice contraindicated in most patients?
- - Monitoring the defect for recurrence
- - distortion of palatal contours and elimination of tongue space (impairs speech)
- -impingement of interocclusal space (no room for prosthesis)
- - accumulations of secretions atop sinus flap (foul odor, sinus infxns)
- (Should be used for very large defects, using fibula flaps)
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* What are some of the lessons learned from our experience using implants in free vascularized flaps?
- DO NOT do immediate placement
- Fibulas with post-op radiation have lower success rates
- Thin the tissues at second stage surgery
- Highly polished surface (PFM) of abutments have better epithelial tissue response
- Overlay type prosthesis preferred for better hygiene and lip support
- * How can these lessons be applied to improve the care of our conventional edentulous implant patients?
- Bone necrosis from wearing dentures- If wearing dentures prior- little risk. If pt receiving new dentures after radiation-higher risk.
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* Prior to free vascularized flaps oral defects secondary to removal of tongue – floor of mouth cancers were closed primarily. What were the functional morbidities that resulted from this practice?
Speech articulation, control of saliva, swallowing, mastication, cosmetic disfigurement
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* Implants placed in fibula free flaps have a very high success rate. Please explain why the rate is so high!
Thick cortical layers enables excellent primary stability.
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* The vertical dimension of occlusion is often closed and the occlusal plane lowered in patients restored with resection dentures. Please explain why!
- To facilitate interaction of tongue with palate (for speech, swallowing)
- To make it easier for tongue to position bolus onto occlusal table
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* The neutrocentric concept occlusion is often used in resection dentures. What is the neutrocentric concept of occlusion and when is it employed in conventional edentulous patients?
No vertical overlap of anteriors, all teeth on same plane except lateral incisors
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* What are some of the challenges we need to overcome when making resection dentures in patients with lateral discontinuity defects of the mandible?
Loss of mand bearing surface, compromised max bearing surface, unilateral occlusal forces, angular path of closure, compromised motor control and sensory input, unfavorable tongue position
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* What are some of the potential benefits derived from use of resection dentures.
- Lateral discontinuity defects
- Restore facial contours
- Restore lip seal
- Mastication
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* What are the three most important prognostic factors when predicting whether a patient will be able to masticate reasonably effectively with a mandibular resection denture. Explain the significance of each of these factors.
- Tongue status- manipulate bolus
- Radiation therapy- affects seal of max CD, tolerance of mand CD,ST irritation
- Mandibular bearing surface- support
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* Lip plumpers are often added to labial flange of mandibular resection dentures. Why?
Improves lip contours, prevents lip biting, permits lip seal (improves salivary control)
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* In edentulous patients treated for tongue-floor of mouth tumors it may be difficult to fit the patient with a well retained maxillary complete denture. Please explain!
- Obliteration of the buccal pouch
- Presence of a ramus fragment
- Deviation of the mandible
- Radiation induced xerostomia
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* Silicone liners should not be used with complete dentures in irradiated patients. Please explain!
- Silicones have DECREASED wettability. Combined with low salivary flow=increased friction
- Silicones deteriorate rapidly
- Silcones are very sifficult to adust
- SILCONE LINERS-->SOFT TISSUE NECROSIS
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* Besides the usual exam findings (tongue position, floor of mouth contour etc) what findings are uniquely important in irradiated patients when considering fabrication of complete dentures
Condition of oral mucous membrane (denture bearing surface) and bony bearing surfaces (undercuts), salivary flow rates, trismus, scarring at tumor site.
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* What radiation delivery findings are important to consider when considering an irradiated edentulous patient for complete dentures?
Fields of radiation, dose to mandibular bearing surfaces
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* In irradiated patients what criteria are used to selected posterior tooth forms?
- Pt coordination, bony contours, tongue and FOM position, jaw relations
- (TOOTH SELECTION NOT BASED ON IRRADIATION)
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* Following cancerocidal doses of radiation boney changes result which may impair osseointegration. What are those changes?
- Reduced vasculature
- loss of osteoprogenitor cells
- fatty degeneration
- compromised remodeling
- susceptibility to osteoradionecrosis
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* The acid etched surfaces are more bioreactive than machine surface implants. Will they (acid etched surfaces) be any more successful in irradiated tissues? Please explain.
HA coated > plasma spray > machined surface
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* Implants can be used in most edentulous patients who have been treated for oral cancer. Why is this statement true? Please explain your answer.
Below 5500cGy little risk of ORN.
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* In the future we will encounter an increasing number of patients with osseointegrated implants who present with oral cancers requiring radiation therapy. If a patient presents with implants in the posterior mandible and this area is to receive 7000 cGy, what would you recommend? Please explain the rationale supporting your recommendation.
- HBO
- Abutments and suprastructures should be removed and/or much mucosa covered over the implant fixtures.
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* Summarize the tissue changes observed in animal studies when implants are placed in irradiated tissues and note the clinical ramifications.
- More woven bone- load bearing capacity
- Death of osteocytes/osteoprogenitor cells- bone remodeling
- Poor blood supply- infxn, implant loss, osteoradionecrosis
- Lower bone appositional index- load bearing capacity
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* Based on the tissue changes noted above what clinical assumptions can you make regarding the use of implants in irradiated tissues?
Less load bearing capacity, lower success rates (equivalent to dosage), osteoradionecrosis (above 6500 cGy in mandible w conventional fractionation), late failures
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* The bone anchorage achieved with acid etched implants is superior to that achieved with machined surface implants. Please explain why this is the case.
Specific genes are expressed which accelerate and enhance deposition of bone on implant surface, leading to improved anchorage and harder/stiffer bone deposition.
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* What are the benefits derived from implant retained prostheses?
Improved retention and stability, elimination of rxns to adhesives, improved skin hygiene and comfort, easier prosthesis placement, maintenance, and life span, enhanced esthetics at prosthesis/skin juncture.
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* Please discuss the differences between craniofacial implants and intraoral implants?
craniofacial typically 4-5mm in length, use magnetic or clip retention
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* What anatomical locations are best for implant placement in the nasal, orbital, and auricular prostheses? Why are magnets used in the orbital prosthesis as opposed to Hader Clips?
- NASAL- floor of nose, glabella
- AURICULAR- posterior and superior to ear canal
- ORBITAL- supraorbital rim (lateral portion)--> magnetic retention used due to ease of insertion/removal and depth perception is impaired
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* What are the steps in fabricating an implant retained prosthesis for prosthetic rehabilitation?
Impressions, master cast, trial sculpting, try on sculpting
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* According to Chang et al, treatment satisfaction of facial prostheses was found to be superior in which aspects of life?
Home > perspiration > eating > exercise-
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* A patient is referred to you prior to radiation therapy to determine whether or not teeth are to be extracted prior to radiation. What criteria should be considered before making decisions regarding extraction of teeth? In each case indicate whether it would make you more aggressive or less aggressive in recommending preradiation extractions.
- Condition of the residual dentition-
- •Furcation involvement of mandibular molars in the field if the dose is above 5500 cGy
- Advanced caries
- Periapical infection
- Periodontal bone loss
- Dental compliance of the patient
- Maxillary vs mandibular teeth (max better blood supply)
- Field, Mode of Delivery, Urgency
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* List those post radiation sequellae which may effect complete denture fabrication and tolerance.
- Mucositis
- Candidiasis,
- ORN,
- Edema,
- Trismus
- Xerostomia
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* Discuss the difference between electrons and photons (high energy) in regard to penetration, definition of fields, bone absorption and skin sparing.
- High energy photon beams (cobalt 60)- deep tumors, skin sparing (*max dose 4-5mm beneath surface)
- Electron/particulate beam- tumors within 6 cm of surface (skin/lymph nodes)
- Combination beam (E + P)- tx of parotid or large skin tumors
- FIELDS:
- - high posterior field (soft palate, tonsillar, nasopharyngeal)- decrease in saliva, low risk of osteoradionecrosis (mandible away from field)
- - opposed mandibular fields- HIGH risk of ORN, but not as much parotid gland involved
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* A dentulous patient is referred to you prior to radiation therapy for a dental evaluation. What information do you need to obtain from the radiation oncologist in order to make treatment recommendations?
Field of radiation, dose of radiation
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* Therapeutic radiation is delivered in a series of fractions. Discuss the biologic phenomenon upon which fractionation is based.
- Series of 200cGy over a 6 week period (total 6500-7200 cGy):
- Allows for reoxygenation of tumor cell (hypoxic) recovery
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* Patient “A” receives 6900 cGy via the linear accelerator for a lateral floor of mouth sq. CA and develops an osteoradionecrosis adjacent to the tumor site. Patient “B” receives 5000 cGy via the linear accelerator and 3000 cGy with an iridium implant for a lateral floor of mouth and sq. CA develops an osteoradionecrosis adjacent to the tumor site. In both patients the bone exposure extends beyond the mucogingival junction. Would these two patients be treated in a similar way? If yes, outline your treatment recommendations. If no, describe your treatment recommendations for each patient.
- o Pt A gets 6900 cGy --> risk of ORN is very high; both buccal and lingual plate get 6900 cGy each, so they will both slough (bad)
- o Pt B: this pt gets 5000 cGy, and has implants; the implants will lead to having 8000 cGy total – this area will necrose
- * Outside area: 5000 cGy --> area will heal
- * Lingual plate on pt B will slough (bc it got 8000 cGy total); but the buccal bone will be okay (bc it only got 5000 cGy total)
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* Describe some of the methods used to minimize the symptoms associated with radiation mucositis.
Multiple beams, brachytherapy
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* How would you describe to a preradiation patient the changes in taste perception they will experience during and after their treatment.
At 5000 cGy, taste almost completely eliminated. First noticed during 2nd week of therapy. Bitter and acid flavors are more susceptible. Taste usually returns to normal 2-4 weeks after therapy (if reasonable salivary flow).
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* Define dosimetry.
Measurement of absorbed dose (gray) of ionizing radiation
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* Define brachytherapy.
Radioactive sources are implanted locally within tissues encompassed by the tumor
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* Describe the “late affects” of cancerocidal doses of radiation on the oral mucous membranes histologically. What are the clinical implications of these changes?
- Immediate cell death--> spontaneous necrosis
- Reproductive DNA damage (functional cell)--> trauma--> proliferation (reproductive death)--> Trauma Induced (delayed) necrosis
- 1. Scarring and fibrosis of lamina propria
- 2. Telangecstasia (dilation of small venules close to epithelial surface)
- 3. Thinner/less keratinized epithelial layer
- - Also have vacuolization and fibrosis of serous acinar cells (salivary glands)
- Clinical Significance: oral mucosa is easily traumatized, developing ulcerations are slow to heal, denture bearing surface has reduced tolerance, Reduced salivary flow rates with more acidic (less buffering) and viscous saliva
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* Chronic Candida albicans infections are common after a definitive course of radiation for an oral cavity tumor. Why is this infection common and how is it best treated?
Fungal organism 100x increase. Nystatin lozenges or oral rinse
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* Describe the microfloral changes in the oral cavity following a definitive course of radiation for head and neck tumors. What is the clinical significance of these changes?
- 1. Increase in Strep. Mutans, Actinomyces, Lactobacillus
- 2. Fungal organisms 100x increase
- Clinical Signficance: Predisposes pt to caries, chronic candidiasis
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* Describe the histologic changes seen in bone after a definitive course of radiation. What is the clinical significance of these changes?
- Early- obliterative endarteritis
- Late- Acellular marrow, fibrous degeneration, fatty degeneration, loss of endosteum and osteocytes, loss of central artery in haversian systems
- Clinical significance: Bone is nonvital-->no remodeling), Impaired response to infection, ORN risk
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* Both amalgam and composite resins have used in post radiation patients. Please discuss the pro’s and con’s of each material when used in this patient population.
- Amalgam preferred (can be extended w recurrent decay, less moisture sensitive, polished AG promote better tissue response)
- Composites have microleakage and difficult moisture control in class V
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* What key facts are important to consider when prescribing topical fluoride for post radiation patients.
- Uptake is confined to 30-50 microns
- penetration is compromised with plaque present
- Much is lost within 24 hours, daily applications are needed
- DO NOT use acidulated phosphate fluorides (dissolved tooth)
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* What are the strategies employed to maintain the dental health of post radiation patients?
- Topical fluoride
- OHI
- Reg follow-up
- 4 mrc
- antiplque rinse
- diet
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* Why are radical alveolectomies recommended when extracting teeth prior to radiation that are within the proposed field of radiation?
Allows for smooth bone and primary closure
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* Discuss the issues and clinical procedures that it is necessary to keep in mind when extracting teeth prior to radiation that are in the proposed radiation fields.
- Wholesale extraction o healthy teeth within the field NOT recommended (increases rate of ORN). Selected tooth extraction (eg- mand molars w furcation involvement) will actually reduce rate of ORN. ORN secondary to preradiation extraction is 10% and treated conservatively w mandibular retention.
- ASSESS:
- DENTAL DISEASE FACTORS (condition of residual dentition, compliance of pt, max vs mand teeth- max teeth have better blood supply/2% ORN risk w good healing as well)
- RADIATION DELIVERY FACTORS (urgency, fields, mode of therapy, dose- >6500cGy no bueno, prognosis)
- PROCEDURES:
- Radical alveolectomy, Care w lingual flap (susceptible to mishandling), teeth removed in segments (helps for primary closure), AB’s, 7-10 days healing prior to radiotherapy
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* Healing times following preradiation extraction and initiation of radiation therapy is dependent on several factors. List them.
- 1. More dental related infection-->more healing time
- 2. Larger wounds-->more healing time
- 3. Trauma inflicted during extractions--> more healing time
- 4. Individual pt factors
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* Discuss the impact of radiation fields upon the risk of osteoradionecrosis and radiation caries
- Loss of vasculature. Mandible worse than maxilla. Dentulous worse than edentulous. Combo of external beam and brachy is worse than external alone, yet more predictable and easier to tx.
- 6500 cGy has up to 10% chance, 7000cGy has up to 30% chance, 7500cGy has up to 50% chance.
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* Please provide examples of the so-called “secondary effects” of radiation therapy on oral tissues.
- 1. Muscle wasting,
- 2. Cranial neuropathies
- 3. Caries
- 4. Osteoradionecrosis.
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* What is the criteria for pre-radiation extractions in terms of dental disease factors and radiation delivery factors?
- Poor dentition
- compliance
- urgency
- fields
- mode of therapy
- dose
- prognosis
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* What surgical procedures are completed at the time of extraction to reduce side-effects of radiation therapy?
- Radical alveolectomy
- Care w lingual flap (susceptible to mishandling)
- teeth removed in segments (helps for primary closure)
- AB’s
- 7-10 days healing prior to radiotherapy
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* What are the options when a patient presents with non-restorable dental disease, ie, severe periodontal disease or advanced caries post radiation?
- Preferred for mand teeth w >5500cGy -->ENDO
- For mand teeth below 5500cGy, out of field, and max teeth -->ENDO OR EXTRACT
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* What are some technical aspects of post-radiation operative dentistry?
- Amalgam preferred (can be extended w recurrent decay, less moisture sensitive, polished AG promote better tissue response)
- Composites have microleakage and difficult moisture control in class V
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* Discuss the pro’s and con’s of the use of pilocarpine in patients with postradiation xerostomia.
Salivary stimulant but requires residual salivary gland parenchyma which may not be found in pts with opposed lateral facial fields (soft palate/nasopharynx tumors). Also may have toxic side effects including increased intestinal motility
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* Many patients suffer from severe trismus following radiation treatment. What is the most effective method of treatment of trismus in this patient population?
Therabite device? Can also use tongue blades
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* What is the role of hyperbaric oxygen in the treatment of osteoradionecrosis? Be specific!
- Stimulation of neovascular proliferation in marginally necrotic tissues
- Fibroblastic proliferation
- enhanced antibacterial activity of white blood cells.
- HBO used when:
- ORN beyond MGJ with >6500cGy by external beam only, ORN precipitated by infection, ORN following brachytherapy that has been UNresponsive to conservative therapy, ORN w significant bone resorption extending to inferior mandible border.
- Includes:
- Stage I- 30 tx’s of 90 minute HBO, if no response; additional 20 HBO
- Stage II- surgical sequestrectomy and 10 HBO tx’s
- Stage III- 30 HBO, bone resection, 10 HBO
- Stage IIIR- mandible reconstruction, 10 HBO
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* Describe the early changes seen in salivary gland tissue histologically during radiation of the salivary glands. Describe the late changes histologically after radiation treatments have been completed. What are the clinical implications of these changes?
- Early changes:
- - 1. Vacuolization of serous acinar cells (occurs at about 1800 cGy)
- - 2. Interstitial fibrosis
- - 3. Progressive loss of the fine vasculature
- Late changes:
- - 1. Progressive fibrosis
- - 2. Almost complete loss of acinar elements and the striated duct system
- -->reduced flow rates, more acidic saliva, less buffering capacity
- -->xerostomia can cause fungal infections, caries, discomfort of prosthesis
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Describe the late changes seen histologically in the periodontal ligament following exposure to cancerocidal doses of radiation. What is the clinical significance of these changes? *
- Loss of cellularity
- Loss of vasculature
- Disorientation of the periodontal ligament fibers
- -->compromised repair (c/i for deep scaling and surgeries)
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* What are the benefits of bisphosphonate therapy?
- – Oral bisphosphonate therapy.- Pagets disease (and osteoporosis for some)
- – IV bisphonate therapy.- for pts w metastatic bone disease: LESS fractures, radiotherapy, bone pain (and pagets)
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* What precautions should you take if the patient is on bisphosphonate therapy?
- – Oral bisphosphonate therapy. – removal of potential sources of dental infxn and irritation before BP therapy
- – IV bisphonate therapy.- avoid surgical procedures while on BP
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If a new patient comes to your clinic for evaluation prior to IV bisphosphonates, what kind of screening procedure along with treatment plan should you perform prior to the start of therapy?
removal of potential sources of dental infxn and irritation before BP therapy
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* What are some clinical manifestation of cancer?
Pain, fatigue, wasting (cachexia), anemia, persistant lumps/swollen glands
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* Describe the TNM system
- T: Size of tumor: non-assessable (TX), no evidence of primary tumor (T0), carcinoma in situ (Tis), increasing in size (T1-T4)
- N: Degree of local invasion/Lymph node involvement: non-assessable (NX), no regional metastasis (N0), involvement of regional lymph nodes (N1-N3)
- M: Metastasis: non-assessable (MX), no distant metastasis (M0), distant metastasis (M1)
- (Spread: CIS, confined to origin, locally invasive, spread to regional structures, distant sites)
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* What are some common side effects of chemotherapy?
Nausea, hair loss, myelosuppression (low RBC, WBC, platelets), mucositis/stomatitis, GI upset and ulceration, reproductive tract complications
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* What is the difference from direct vs. indirect stomatotoxicity?
- DIRECT= reduction in renewal rate of basal layer cells (mucosal atrophy/ulceration)
- INDIRECT= affects a cell pool other than oral mucosa (neutropenia, thrombocytopenia)
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* Which classifications of chemotherapeutic agents have the highest incidence of oral mucositis?
ALKYLATING AGENTS, ANTIMETABOLITES, ANTITUMOR ANTIBIOTICS
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* What is the incidence and consequence of oral mucositis?
- 40% incidence. Pain, bleeding, infection
- Define induction, adjuvant, salvage, and neoadjuvant chemotherapy.*
- INDUCTION- when no alternative tx is available
- ADJUVANT- after initial surgery/therapy (minimizes recurrence)
- SALVAGE- after recurrence of refectory tumor
- NEOADJUVANT- PRIOR to definitive tx (reduces tumor burden during surgery/radiation)
- (chemosensitive- given WITH radiation)
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* If a patient of yours tells you that he/she will be initiating chemotherapy in the next couple of weeks, what should be you plan in regards to dental care?
Eliminate gross infxn, treat carious lesions, adjust dentures, ortho, for pedo--> remove mobile primary teeth and gingival operculum
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* In consulting the medical oncologist for planned dental care, what pertinent questions should you ask in the following type of care? What is expected neutrophil and platelet count?
- 1500 N/60k P: normal tx, MD consult, antibiotics
- 500-1500 N/20k-60k P: emergency tx, platelet transfusion for surgery
- BELOW 500 N/20k P: NO REST TX
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* In consulting with the oncologist, he/she mentions that the patient’s blood count will be at nadir in a week. What does that mean to you?
- NADIR= point at which blood count is at its LOWEST
- Dental Tx should be delayed until BETWEEN 3RD AND 4TH WEEK AFTER CHEMO
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