- Email: [email protected]
Where to start treatment
the original substructure bar that remained. The new segment was soldered in place. For the overdenture, a new patrix attachment housing with a new patrix attachment firmly attached to it was secured to the matrix attachment on the repaired segment of the bar (Fig 4). The remaining connections were made, and the overdenture was finished and polished. The prosthesis was then inserted, demonstrating excellent retention.
Fig 4.—With previous patrix housing removed from suprastructure, occlusal access opening was created to enable transfer of new patrix housing and new attachment with autopolymerizing acrylic resin. (This figure was published in J Prosthetic Dent, 96, Rasmussen JM, Koka S, Echert SE, et al, Repair of a milled cantilevered implant overdenture bar: A clinical report, 84–87, Copyright The Editorial Council of the Journal of Prosthetic Dentistry (2007).)
placed, the definitive impression was poured. The original substructure bar was then fitted onto the abutment analogs in the new cast to ensure there was no distortion when the impression was made or the cast fabricated. Reference measurements were obtained before removing the fractured segment. A surveyor was then used to chart the path of insertion for the matrix attachments. Once the fractured segment was removed, a waxing was made for the replacement segment (Fig 2). This included a new gold cylinder and 1 matrix attachment (Fig 3). The segment was invested and cast in gold alloy. This replacement piece was put in place on the final cast with
Discussion.—Generally four factors significantly affect the chances of fatigue failure in implant dentistry. These include biomaterial used, macrogeometry involved, force magnitude present, and number of cycles used. When the fractured segment of this patient’s IOD was repaired, the distal extension of the cantilever was shortened. This decreased the amount of force on the system. By decreasing cantilever length, both the macrogeometry and the force magnitude were positively influenced in a way that should minimize the chance of future fatigue failure.
Clinical Significance.—Making the case originally is one thing; salvaging it when something breaks is another. Presented is the replacement of a fractured segment of an implant overdenture bar.
Rasmussen JM, Koka S, Echert SE, et al: Repair of a milled cantilevered implant overdenture bar: A clinical report. J Prosthetic Dent 96:84-87, 2006 Reprints available from J Rasmussen, Div of Prosthodontics, Mayo Clinic, 200 First St SW, Rochester, MN 55905; fax: 507-284-8082; e-mail: [email protected]
Restorative Dentistry Where to start treatment Background.—If a tooth requires both crown lengthening and endodontic treatment, the sequence of treatment comes into question. Endodontic Treatment First.—When there are symptoms related to endodontic involvement, pulpectomy is needed first, assuming there is sufficient tooth structure to place a rubber dam clamp, isolate the tooth, and prevent saliva from escaping. Cleaning, shaping, and medicating the root canal system becomes the first priority. Pretreatment measures may be needed, such as gingivectomy to expose
tooth structure to be gripped or placing build-up material on the remaining crown to help stabilize the clamp. The gingiva can be clamped to isolate the tooth if absolutely necessary; cotton rolls can help cushion the effects of clamping on the gingival tissues. Once the tooth is adequately isolated, permanent filling material (post-and-core buildup) can be accomplished. Delaying Endodontic Treatment.—If isolation cannot be accomplished using a rubber dam, the root canal treatment should be delayed until after the crown lengthening
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2007
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procedure. If the root canal treatment is not delayed, the temporary filling could develop a leak. If there is a break of 2 to 3 months between root canal treatment and crown lengthening, the root canal system can become contaminated, requiring endodontic retreatment. Evidence of coronal leakage includes finding a wet cotton pellet that was over the obturation material after the temporary filling material is removed or a foul odor when the access filling is removed. If gutta-percha is exposed to bacteria, the root canal system can become contaminated within a couple of weeks. To avoid having to perform endodontic treatment twice because the crown lengthening procedure is delayed and leakage is found, it is better to wait and obturate the root canal after lengthening the crown. Generally endodontic treatment can be accomplished within a few weeks after the crown-lengthening surgery. Management of Leakage.—If coronal leakage develops after the canals have been instrumented and medicated, apply calcium hydroxide paste for its antibacterial properties. This assumes that the problem is simple leakage, not dislodgment of the access filling. Sodium hypochlorite and a final rinse with 15% to 17% ethylenediaminetetra-acetic acid solution will disinfect and open the dentinal tubules before obturation after surgery.
Discussion.—When both endodontic therapy and crown lengthening procedures are required in a tooth that cannot be adequately isolated for permanent restoration placement, endodontic treatment is generally performed first. This allows the dentist to determine the working length that is available. Next the crown lengthening procedure can be performed, followed by obturation of the tooth. Buildup of the tooth can be accomplished immediately because rubber dam isolation is possible, eliminating salivary contamination and bacterial exposure.
Clinical Significance.—This situation presents the conundrum, who goes first? Can a rubber dam clamp be placed in order to isolate? Can the entire canal length be negotiated? If recontamination occurs before post-core placement, decontaminate or retreat? Surgerize first to allow adequate isolation? All these issues need to be properly sequenced.
Coil J: What is the treatment sequence for a tooth that requires both root canal treatment and crown lengthening? J Can Dent Assoc 72:897-898,2006 Reprints available from J Coil; e-mail: [email protected]
Sleep Disorders Dentists treating sleep apnea Background.—The American Academy of Sleep Medicine recently facilitated the practice of dentists treating sleep disorders by issuing new guidelines saying oral appliances are a recommended first-line approach for mild to moderate sleep apnea. This recognizes a practical reality. Although continuous positive airway pressure therapy is the first choice for treatment, more than 60% of patients stop wearing the continuous positive airway pressure device after 1 year. Oral appliances were reported by Internal Medicine News to be more effective than surgery or over-the-counter products. Measuring Sleep.—Dentists can ask questions to screen potential candidates for sleep disorders. For example, if a patient reports not dreaming much, a sleep disturbance may be keeping him or her from reaching the rapid eye movement stage of sleep, where dreams are more likely. Dentists also have a new ambulatory sleep monitoring tool,
228
Dental Abstracts
Watch-PAT 100. The device is worn on the wrist and uses a probe over 2 fingers. Breathing can then be tested at home, with PAT telling whether blood vessels are dilated or constricted. The Watch-PAT thereby measures respiratory disturbances, oxygen saturation, and actigraphy. Pulse rate and rapid eye movement stage sleep are also measured. The device costs less than a sleep laboratory visit and permits the patient to sleep in his or her own bed. For garden-variety snoring or sleep apnea, the Watch-PAT 100 will give accurate results. The device tells how many apnea episodes occur, the oxygen level and whether it falls below a set limit, how many times the person awakens during the night, and generally, what is really happening during sleep times. Diagnosis.—Patients can go to their doctor for a diagnosis and possible medical insurance coverage. Cautious dentists may decline to make snoreguards without a doctor’s
Fig 4.—With previous patrix housing removed from suprastructure, occlusal access opening was created to enable transfer of new patrix housing and new attachment with autopolymerizing acrylic resin. (This figure was published in J Prosthetic Dent, 96, Rasmussen JM, Koka S, Echert SE, et al, Repair of a milled cantilevered implant overdenture bar: A clinical report, 84–87, Copyright The Editorial Council of the Journal of Prosthetic Dentistry (2007).)
placed, the definitive impression was poured. The original substructure bar was then fitted onto the abutment analogs in the new cast to ensure there was no distortion when the impression was made or the cast fabricated. Reference measurements were obtained before removing the fractured segment. A surveyor was then used to chart the path of insertion for the matrix attachments. Once the fractured segment was removed, a waxing was made for the replacement segment (Fig 2). This included a new gold cylinder and 1 matrix attachment (Fig 3). The segment was invested and cast in gold alloy. This replacement piece was put in place on the final cast with
Discussion.—Generally four factors significantly affect the chances of fatigue failure in implant dentistry. These include biomaterial used, macrogeometry involved, force magnitude present, and number of cycles used. When the fractured segment of this patient’s IOD was repaired, the distal extension of the cantilever was shortened. This decreased the amount of force on the system. By decreasing cantilever length, both the macrogeometry and the force magnitude were positively influenced in a way that should minimize the chance of future fatigue failure.
Clinical Significance.—Making the case originally is one thing; salvaging it when something breaks is another. Presented is the replacement of a fractured segment of an implant overdenture bar.
Rasmussen JM, Koka S, Echert SE, et al: Repair of a milled cantilevered implant overdenture bar: A clinical report. J Prosthetic Dent 96:84-87, 2006 Reprints available from J Rasmussen, Div of Prosthodontics, Mayo Clinic, 200 First St SW, Rochester, MN 55905; fax: 507-284-8082; e-mail: [email protected]
Restorative Dentistry Where to start treatment Background.—If a tooth requires both crown lengthening and endodontic treatment, the sequence of treatment comes into question. Endodontic Treatment First.—When there are symptoms related to endodontic involvement, pulpectomy is needed first, assuming there is sufficient tooth structure to place a rubber dam clamp, isolate the tooth, and prevent saliva from escaping. Cleaning, shaping, and medicating the root canal system becomes the first priority. Pretreatment measures may be needed, such as gingivectomy to expose
tooth structure to be gripped or placing build-up material on the remaining crown to help stabilize the clamp. The gingiva can be clamped to isolate the tooth if absolutely necessary; cotton rolls can help cushion the effects of clamping on the gingival tissues. Once the tooth is adequately isolated, permanent filling material (post-and-core buildup) can be accomplished. Delaying Endodontic Treatment.—If isolation cannot be accomplished using a rubber dam, the root canal treatment should be delayed until after the crown lengthening
Volume 52
Issue 4
2007
227
procedure. If the root canal treatment is not delayed, the temporary filling could develop a leak. If there is a break of 2 to 3 months between root canal treatment and crown lengthening, the root canal system can become contaminated, requiring endodontic retreatment. Evidence of coronal leakage includes finding a wet cotton pellet that was over the obturation material after the temporary filling material is removed or a foul odor when the access filling is removed. If gutta-percha is exposed to bacteria, the root canal system can become contaminated within a couple of weeks. To avoid having to perform endodontic treatment twice because the crown lengthening procedure is delayed and leakage is found, it is better to wait and obturate the root canal after lengthening the crown. Generally endodontic treatment can be accomplished within a few weeks after the crown-lengthening surgery. Management of Leakage.—If coronal leakage develops after the canals have been instrumented and medicated, apply calcium hydroxide paste for its antibacterial properties. This assumes that the problem is simple leakage, not dislodgment of the access filling. Sodium hypochlorite and a final rinse with 15% to 17% ethylenediaminetetra-acetic acid solution will disinfect and open the dentinal tubules before obturation after surgery.
Discussion.—When both endodontic therapy and crown lengthening procedures are required in a tooth that cannot be adequately isolated for permanent restoration placement, endodontic treatment is generally performed first. This allows the dentist to determine the working length that is available. Next the crown lengthening procedure can be performed, followed by obturation of the tooth. Buildup of the tooth can be accomplished immediately because rubber dam isolation is possible, eliminating salivary contamination and bacterial exposure.
Clinical Significance.—This situation presents the conundrum, who goes first? Can a rubber dam clamp be placed in order to isolate? Can the entire canal length be negotiated? If recontamination occurs before post-core placement, decontaminate or retreat? Surgerize first to allow adequate isolation? All these issues need to be properly sequenced.
Coil J: What is the treatment sequence for a tooth that requires both root canal treatment and crown lengthening? J Can Dent Assoc 72:897-898,2006 Reprints available from J Coil; e-mail: [email protected]
Sleep Disorders Dentists treating sleep apnea Background.—The American Academy of Sleep Medicine recently facilitated the practice of dentists treating sleep disorders by issuing new guidelines saying oral appliances are a recommended first-line approach for mild to moderate sleep apnea. This recognizes a practical reality. Although continuous positive airway pressure therapy is the first choice for treatment, more than 60% of patients stop wearing the continuous positive airway pressure device after 1 year. Oral appliances were reported by Internal Medicine News to be more effective than surgery or over-the-counter products. Measuring Sleep.—Dentists can ask questions to screen potential candidates for sleep disorders. For example, if a patient reports not dreaming much, a sleep disturbance may be keeping him or her from reaching the rapid eye movement stage of sleep, where dreams are more likely. Dentists also have a new ambulatory sleep monitoring tool,
228
Dental Abstracts
Watch-PAT 100. The device is worn on the wrist and uses a probe over 2 fingers. Breathing can then be tested at home, with PAT telling whether blood vessels are dilated or constricted. The Watch-PAT thereby measures respiratory disturbances, oxygen saturation, and actigraphy. Pulse rate and rapid eye movement stage sleep are also measured. The device costs less than a sleep laboratory visit and permits the patient to sleep in his or her own bed. For garden-variety snoring or sleep apnea, the Watch-PAT 100 will give accurate results. The device tells how many apnea episodes occur, the oxygen level and whether it falls below a set limit, how many times the person awakens during the night, and generally, what is really happening during sleep times. Diagnosis.—Patients can go to their doctor for a diagnosis and possible medical insurance coverage. Cautious dentists may decline to make snoreguards without a doctor’s