DENTAL MANAGEMENT OF PATIENTS UNDERGOING RADIOTHERAPY TO HEAD AND NECk
Radiotherapy (i.e., radiation therapy, x-ray treatment) is a common therapeutic modality for malignancies of the head and neck. Approximately 30,000 cases of ‘head and neck cancer occur each year. Many of these are managed by therapeutic irradiation. Its’ use is ideally predicated on the abilitv of the radiation to destroy neoplastic cells while sparing normal cells. In practice; howl ver, this is never actually achieved, and normal tissuesexperience some undesirable effect. Any neoplasm can
be destroyed by radiation if the dose delivered to the neoplastic cells is sufficient. The limiting factor is the amount of radiation that the surrounding tissues can tolerate.
Early in the’ course of radiotherapy, the oral mucosa shows the effects of treatment. The changes in and around the oral cavity as the result of destruction of the fine vasculature are most notable to dentistry. Salivary
glarids and bone are relatively radioresistant, but because ‘of the intense vascuiar compromise resultirig from radiotherapy, these tissues bear a considerable hardship in the long run.
Radiation Effects on Oral Mucosa
The initial effect of radiotherapy On the oral mucosa, which is seen in the first 1 or 2 weeks, is an erythema that , may progress to a severe mucositis .with or without ulceration. Pain and dysphagia may be severe and make Mequate utritional intake difficult. These mucosal reactions beg n to subside after completion of the course of radiothera y. The taste buds, also comprised of epithelial cells, show similar reactions. Loss of taste is it prominent complaint early in treatment and gradually returns, depending
on the quantity and quality of saliva that remains after treatment.
Radiation Effects on Salivary Glands
Salivary gland epithelium has a very slow turnover rate therefore the salivary glands might be expected, to be radioresistant. However, because of’the destruction of the fine vasculature by the radiation, the salivary glands show considerable damage, with resultant atrophy, fibrosis, and degeneration. This manifests clinically as xerostomia (the decreased production of saliva) and gives the patient a “dry mouth.” The severity of xerostomia , depends on which salivary glands were within the field of
radiation. A dry mouth may be the patient’s most significant complaint.
Treatment of Xerostomia
After radiotherapy, patients often complain of chronic dry mouth. At present no general agreement exists U)fJ’ cerning how to prevent these changes. Unfortunatety. in many cases, xerostomia never improves substantially, and exogenous replacement of saliva is necessary, For the
simplest form of replacement, water .can be sipped throughout the day. In addition, several saliva substitutes can be obtained without a prescription at the pharmacy. These substitutes contain several of the ions in saliva and’
other ingredients (e.g., glycerin) to mimic the-lubricating action of saliva. Unfortunately; artificlal salivas. on the market do not possess the protective proteins that are present in the salivary secretions. The patients are therefore still prone to the problems induced by xerostomia,
For comfort, owever, many patients seem to be just as
satisfied with plain water as artificial salivas and keep small quantities available’ at all times to Sip.
Radiation Effects on Bone
One of the most severe and complicating sequelae Qf radiotherapy for patients with head and neck cancer is osteoradionecrosis (Fig. 18-2). Basically, osteoradionecrosis is devitalization of the bone by cancericidal doses of radiation. The bone within the radiation beam becomes
virtually non vital from an endarteritis that results in elimination of the fine vasculature within the bone. TQe turnover rate of any remaining viable bone is slowed to the point of being ineffective in self-repair. The continual
process. of remodeling normally found in bone does t occur, and sharp areas on the alveolar ridge will notsmooth themselves, even with onsiderable time. Theone of the mandible is denser and has a poorer bloodsupply than that of the. maxilla. Thus the mandible is thejaw most commonly affected with nonhealing ulcerations’and osteoradionecrosis.
Other Effects of Radlation
Patients undergoing radiotherapy may have an alteration in the normal oral flora, with overgrowth of anaerobic species and fungi. Most researchers feel that oral flora onizing the mucous membranes play an important role in the 2everity of, mucositis and subsequent healing .
FIG. 18-1′ A, Typical ‘clinical appearance of radiation caries, 8, Typical radiographic appearance
of radiation caries, Note the erosion around the cervical portion of the teeth
process.v’ Candida albicans commonly thrives in the oral cavities of patients who have been irradiated. It is not known whether the .alteratlon in the flora is caused by the radiation itself or the resultant xerostomia. Patients frequently require .the application of topical antifungal agents, such as nystatin, to help control the amount of Candida organisTl}s present. Another oral rinse frequently prescribed is 0.1 i)1c) chlorhexidine (Peridex). This agent has been shown to have potent in vitro antibacterial and antifungal effects. When used throughout the course of radiation treatment, it has been shown in at least one study to greatly reduce the prevalence and symptoms associated with radiation-induced mucositts.” Its use in other studies has been equlvocal.
Evaluation of Dentition Before Radiotherapy
The most feared side effect of radiotherapy is osteoradionecrosis.
Most patients develoment coin plication have residual teeth throughout the course of radio therapy. Thus the clinician may wonder what to do with
‘the teeth before irradiation. Should teeth be extracted.This question has no categorical answer; however, severo al factors must be eonsldered.
Condition of residual dentition.
All teeth with a -questionable or poor prognosis should be extracted before radiotherapy. The more advanced the periodontal condition, the more likely the patient is to develop caries and continued periodontitis. Although this may not be in keeping with usual dental principles, if in doubt, extract. Extraction in these cases may spare the patient months or
years of suffering from osteoradionecrosis .
Patient’s dental awareness.
The present state of the dentition and periodontium is a good clue to the past care they have received. In patients with excellent oralhygiene
and oral health, they should retain as many of the teeth as possible. Conversely, in patients who have neglectedoral health for years, the chances are
FIG, 1R-2 Pr
c.gres5,v(: course of usteoradionecrosls- A, Rau,ograph showing radiolucencies in right
rnand.bl« and around apex of molar tooth. 5, Six months later, during which time antibiotics and local
irrigations were used, radiolucent: ress is spreading into ramus, Molar was removed at this time.
C, Five months tier tooth removal” raction site did not heal and destructive process spread, resultillg
in p:1lhologic fracture of rnandib l D, Radiograph after removal of devitalized bone, showing
extent of process. (Courtesy Dt. Richard coot, Ann Arbor, M/.
severe xerostomia and oral pain, which wil] make oral hygiene even more dillicult- I’rL’r”diotherapy patient preparatiun is similar to preorthodontic patient preparation. If an indiv idual cannot or will not can.’ for his or her
mouth before the application oi the braces, it will be impossible for him or her to do so when faced with ruture obstacles.
Radiation Location. The more saliyary glands ami bone involved in the field of radiation, the more severe will be the resultant xerostomia and vasi ular compromise of the jaws, Thus the dentist should discuss with the
radiotherapist the locations of the radiation beams and esnrnate tho seyerity of the probable xerostomia and hone changes, Xerqstomia by itself may not result- in the problems if the dentition can be maintained, bccduse the bone is still healthy, It is the combination of xerostomia and irradiated Done that usually causes theproblem. In individuals who will have radiation to the major salivarv glands and a portion of the mandible,
preirradiatlon extractions should be considered the radiotherapist agrees to delay the institution of irradiation for 1 to 2 weeks if the dentist feels that time is necessary to allow the extraction sites to begin to heal.
Squamous cell-carcinomas of the Of!!1cavitv make up approximately 9()’!i. of malignant tumors for which radiation therapy is used. Unfortunately, this cancer requires a \’ery large dose of radiation (greater tl1.1116000 rads [60 Gy]) to effect a result. Other malignancicv, such as 1~’I11-
phoma, require much less radiation fur a response, and the oral cavity wi]] therefore be less affected. Wilen the total dose falls below 5000 rads (50 G~·l. long-term side effects, such as xerostomia and osteoradionecrosis, are
dramatically decreased.
Preparation of Dentition for Radiotherapy
Every tooth to be maintained must be carefully inspected for pathologic conditions and restored to the best state of . health obtainable. A thorough prophylaxis and topical fluoride application should be performed before radiotherapy, Oral hygiene measures and instructions should be demonstrated and reinforced. Any sharp cusps should be rounded to prevent mechanical irritation. Impressions for dental casts should be obtained for fabrication of custom fluoride trays to be used during and after treatment, Because tobacco use and alcohol consumption irritate the
mucosa, the patient should be encouraged to stop these before commencement of radiation therapy.
After radiation treatment the dcntivr should see the patient every 3 to months prophylaxis is performed during these postirradiation visits, and topical fluoride • applications are made. The patient should be fitted with custom trays to deliver topical fluoride applications, The patient should be instructed in the use of the trays and in daily self-administration of topical fluoride applications. The use of a 1% fluoride rinse for 5 minutes each day has been found to decrease the incidence of radiation caries. II Over-the-counter fluoride rinses currently available can be used without a customized delivery splint with good success and seem to haw better tient acceptance.
Method of Performing Preirradiation Extractions
If the decision has been made to extract some or all teeth before radiotherapy, the question becomes, “How should the teeth be extracted?” In general, the principles of atraumatic exodontia apply. However, the concepts of bone preservation are disregarded, and an attempt is
made to remove a good portion of the alveolar process along with the teeth and achieve a primary soft tissue closure. With the onset of radiotherapy, the normal remodeling process is inhibited; if any sharp areas of bone exist,
ulceration occurs with bone exposure. Thus the teeth are usually removed in a surgical manner, with flap reflection and generous bone removal.
Note: The dentist is ill a race against time. If the WOLIlld. ails
t(l heat, tile radiotherapv will b.e delaye.t. If the radiation i elivered /}(‘(ol’e the wound heals, Ilcalil1S will take months or e\’el/ years.
Interval Between Preirradiation Extractions and Beginning of Radiotherapy
time should be allowed after extractions before beglnning radiotherapy. Obviously, the sooner radiotherapy is begun, the more beneficial it may be. Thus when the soft tissues have healed sufficiently, radiotherapy may begin. Iraditionally. 7″to 1-1days between tooth extraction and radiotherapy have been suggested.’·12.11 Most authors
base their recommendations on the clinical impression that rcepltheliallzatlon has occurred in this period. Howeve
radiotherapy should be delayed for 3 weeks after extraction, if possible. This helps to ensure that sufficient soft ttssu« hl’0ling has occurred. The radiotherapy should be delayed further, if )Jm’>ible, if a local wound dehiscence has {Jl’ ~IIT(‘d. In thi~ invtancc d,lily local wound care with irrigations and postoperative antibiotics aremandatory until the soft tissues have healed.
Tooth Extraction After Radiotherapy
Can teeth be extracted after radiotherapy and, if so, how These are probably the most difficult questions to answer. Each dentist has a view 011 this subject, and the literature is contradictory. Postirradiation extractions are also the most undesirable extractions the dentist will ever perform,
because the outcome is always uncertain.The answer to the question of whether extractions COIl be done after radiotherapy is certainly, yes. The more important question is, How? If the tooth is to be extracted,
the dentist can either perform 11 simple extraction without primary soft tissue closure or a surgical extraction with alveoloplasty and primary closure. Either of these techniques yields similar results, with a certain concomitant incidence of osteoradionecrosis. The use of systemic
antibiotics is recommended.
Denture Wear in Postirradiation Edentulous Patients
Patients who were edentulous before radiotherapy manage very nicely-with well-constructed dentures-However, . patients rendered edentulous just before or after radiotherapy exhibit more problems with mucosal ulcerations and subsequent- osteoradionecrosis. The normal remodeling
process of the alveolar bone cannot smooth even the most minor irregularities left by extraction. With denture wear, these minor irregularities cause ulceration of the mucosa.
Use of Dental Implants in Irradiated Patients
The dental rehabilitation of the edentulous patient who has received radiation therapy is one of the greatest challenges facing the reconstructive dentist.· Many patients who have had ablative surgery for malignancy do not have the normal anatomy that makes denture wear possible.
There may be no vestibules tG accommodate a denture flange.
The time required for osseointegration will be prolonged in irradiated patients because of the lower metabolic activity. in the bone, “so the implants should not be loaded for at least 6 months after placement. The dentist must pay particular attention to oral hygiene in such
patients, because theirtissues will not beas able to resist bacterial invasion as tissues in patients who have not been irradiated. The prosthetic design should therefore be made as cleansable as possible, with frequent use of overdentures. These patients will require more careful followup
and hygiene measures.
In spite of the fear that implants placed into irradiated bone will d to osteoradionecrosis, it is uncommonly reported in e literature.21.22 However, there has been an , insufficient duration of experience to predict the longterm outcome of implant prosthetics in the patient who has undergone radiation.
Managmentof Patients Who DevelopOsteoradionecrosis
Most mucosal breakdown and subsequent osteoradionecrosis occur in the mandible. They occur most often in mandibles that have received radiation in’ excess of 6500 rads (65 Gy) and do not usually occur in mandibles
that have received radiation doses below 4800 rads (48Gy).23.25Severe pain may follow. The patient should discontinue wearing any prosthesis and try to maintain a good state of oral health. Irrigations should be instituted to remove necrotic debris (Fig. 18-3). Only occasionally’
are systemic – antibiotics necessary, because osteoradionecrosis is not an infection of the bone but rather a nonhealing hypoxic wound.P Because of the decreased vascularity of the tissues, systemic antibiotics do not gain
ready access t the area to perform thefunction for which they are intended. However, in acute secondary infections, antibiotics maybe useful to help prevent spread of the infection. Any loose sequestra are removed, but no
attempt is made in ially to close the soft tissues over the exposed bone. Most wounds smaller than 1 cm eventual. ly heal, although it may take weeks to months. For non healing wounds or ,extensive areas.
Reconstructive efforts with bone grafts used for conti nuity defects can also be undertaken successfully in many patients who have undergone irradiation. Free microvascular grafting techniques are becoming more popular for restoring continuity defects in patients who have
received radiotherapy. These bone grafts have their own blood supply from a reconnection of blood vessels and are therefore less dependent on the local tissues for incorporation and. healing.
![FIG. 18-3 Osteoradionecruso vI tile lei, Ill,'; " ..ble, IL" i'",.l:;I~II~d " i,,:1 ~(",r)l: of tumoricidal radiotherapy for squamous cell corclnorna. The dentition W,l~ lemovt:d at the time of the cancer resection. This patient was prep-red fur treatment of the osteor,ldion<:crosis with pre- and postoperative hyperbaric oxygen treatments. A, Exposed devrtal hone: alan'] alveolar ridge of left mandible. B, Panoramic radiograph she-vine diffuse irregularity without good coruccuon of alveolar crest. C, Surgical exposure of tile area shows dcvital bone rnarqins and cl celltr,,1 oau.r devoid 01 bone](https://www.medassignments.com/wp-content/uploads/2014/08/443-209x300.jpg)
FIG. 18-3 Osteoradionecruso vI tile lei, Ill,’; ” ..ble, IL” i'”,.l:;I~II~d ” i,,:1 ~(“,r)l: of tumoricidal
radiotherapy for squamous cell corclnorna. The dentition W,l~ lemovt:d at the time of the cancer resection.
This patient was prep-red fur treatment of the osteor,ldionhyperbaric oxygen treatments. A, Exposed devrtal hone: alan’] alveolar ridge of left mandible.
B, Panoramic radiograph she-vine diffuse irregularity without good coruccuon of alveolar crest.
C, Surgical exposure of tile area shows dcvital bone rnarqins and cl celltr,,1 oau.r devoid 01 bone
_FIG. 18-3-<:ont’d 0, The bone.of the alveolar crest is removed, and the remainder
smoothed with a bur until bleeding bone is encountered. The central crater is similarly burred
out. E, Resected specimen of alveolar crest
![FIG. 18-3 Osteoradionecruso vI tile lei, Ill,'; " ..ble, IL" i'",.l:;I~II~d " i,,:1 ~(",r)l: of tumoricidal radiotherapy for squamous cell corclnorna. The dentition W,l~ lemovt:d at the time of the cancer resection. This patient was prep-red fur treatment of the osteor,ldion<:crosis with pre- and postoperative hyperbaric oxygen treatments. A, Exposed devrtal hone: alan'] alveolar ridge of left mandible. B, Panoramic radiograph she-vine diffuse irregularity without good coruccuon of alveolar crest. C, Surgical exposure of tile area shows dcvital bone rnarqins and cl celltr,,1 oau.r devoid 01 bone](https://www.medassignments.com/wp-content/uploads/2014/08/443.jpg)
