Troubleshooting the Herbst Appliance
Contents
1. Fig 4 4 Eruption of mandibular bicuspid during appliance fabrication Solution Note on the laboratory prescrip tion if a bicuspid will erupt while the Herbst is being fabricated The lab technician can then allow for the 4 2mm of eruption by adjusting the rest or crossover wire occlusally Fig 5 If this is not done the Herbst will not seat fully 5 Loose bands Solution Microetch crowns or bands to increase surface area and retention This is usu ally done by the lab Microetching will also help the cement adhere to the band instead of the enamel on removal Tip A band or crown that is too large or that becomes stretched when loose can be tightened by crimping the gingival margin with a birdbeak plier Fig 6 Keiba Heavy Cutting Plier Part No PU 266 Great Lakes Orthodontics Ltd 199 Fire Tower Drive Tonawanda NY 14150 with birdbeak plier 269 Troubleshooting the Herbst Appliance Fig 7 Ceka Bond applied to screw to keep it from unseating a p Eeee S a Fig 9 Archwire covered with plastic tubing to avoid sore spots Fig 8 Sore spots from transpalatal arch 6 Cement fractures Solution Use a strong cement such as Fuji 1 Etching the teeth with GC Ortho a 10 polyacrylic acid conditioner will also improve bond strength Tip If an appliance comes off the cement can be removed by heating it slightly with a Bunsen burner or torch and then dousing2. j lk lee he Leer mm eis or ers mr gopr el ei ee Deiere Fhe AA RPGR G Thij DARGENT biep Be epee ede Tia eet ae 2 a_i a eS a cried oC PP AE ma Be mere ed oo ma Pe ei be che La f 3 eo Dre Hrn mie ia Fig 22 Signed statement on chart concerning need for second phase of fixed appliance treatment appointment explain that the Herbst is correct Conclusion ing the jaw relationship and that the orthopedic phase must be followed by an orthodontic phase to align the teeth Prevent any misunderstanding about the need for Phase II treatment with full appliances by including an appropriate statement on the patient s chart and on the contract Fig 22 The popular Herbst appliance becomes even more efficient when these troubleshooting tips are followed Knowing what to do in case of a problem helps avoid an emergency atmosphere in the office and allows the orthodontist and staff to gain confidence in incorporating the appliance into their practice routine 274 JCO MAY 2002
3. molar will prevent the screw casing from impinging on the rami 11 Pivot screw impinging on the cheek Solution To hold the cheek away from the pivot a cotton roll can be attached to the appli ance with an elastic tied in a slipknot Fig 11 If sore spots develop the screws can be covered with Comfort Capst Fig 12 Since these stay in place for only a few days it is not advisable to use them on every Herbst case Mushroom Comfort Solutions 305 20897 57th Ave Langley BC V3A 8L5 Canada VOLUME XXXVI NUMBER 5 Rogers Fig 13 Larger mushroom screw can be used in any quadrant if sore spot develops Fig 14 Broken upper screw head grooved with bur and unscrewed with scaler screws which have a 2mm greater diameter than regular Herbst screws can also be used to help sore spots heal Fig 13 These screws should not be used routinely however because the larger heads tend to bind on the rods in later al movements and thus to break off more often 12 Broken screw heads Solution For a broken upper screw head remove the band or crown groove the screw stem with an S S White RA 35 slow speed bur and remove the screw with a scaler or a small jeweler s screwdriver Fig 14 A broken 5 5mm hex screw Ormco A Company 1717 W Collins Ave Orange CA 92867 8 S White 151 Old New Brunswick Road Piscataway NJ 08854 271 Troubleshooting the Herbst Appliance Fig 15 Brok
4. Troubleshooting the Herbst Appliance MICHAEL B ROGERS DDS T Herbst is one of the most popular appli ances used today for Class II correction because it is durable and fixed and therefore does not require special patient cooperation Although problems are infrequent with the use of today s improved cements and techniques any appliance placed in an active oral environment will encounter occasional difficulties This arti cle will offer guidelines on fabricating the Herbst and troubleshooting problems when they occur Potential Problems 1 Distortion of models Solution Take accurate impressions pour alginate impressions immediately or pour poly vinyl siloxane impressions after 30 minutes Tip Wrap an alginate impression in a wet towel while it is waiting to be poured Fig 1 2 Improper placement of bands or crowns in impressions Registered trademark of Dentaurum Inc 10 Pheasant Run Newtown PA 18940 Pacer Technology 9420 Santa Anita Ave Rancho Cucamonga CA 91730 Fig 1 Alginate impression wrapped in wet towel while waiting to be poured 268 2002 JCO Inc Solution If the direct method is being used the orthodontist not an assistant should super glue the bands or crowns into the impression for accuracy Fig 2 This can be done at the chair before the appliance is disinfected After the glue has dried vibrate the impression on low while pouring so that the super glue bond will
5. e tubes can not be lengthened because the appliance would be overadvanced an elastic can be used to help keep the appliance together Fig 19 16 Frequent disengagement when upper prima ry second molars are used for anchorage If the upper first permanent molars have not erupted sufficiently for banding the primary sec ond molars must sometimes be used Solution Move the pivots about 2mm distally on the bands or crowns Fig 20 Moving the pivots distally VOLUME XXXVI NUMBER 5 Fig 21 Broken wire and pivot and missing crown e Patient destroyed both crown and banded Herbst appli allows for longer tubes which will keep the appliance from coming apart every time the patient opens 17 Chronic and excessive appliance breakage Solution Do not use the Herbst in autistic children patients with severe bruxism or ex tremely uncooperative children Fig 21 The Herbst like all other appliances requires proper patient selection 18 Parental misunderstanding about the Herbst phase of treatment Solution At the exam and or consultation 273 Troubleshooting the Herbst Appliance Full arotile mit wr Dit extract the four first hecuapids d Lior cut Ce ipdbersiomd that the Bite may slay phili upe ned irori ihe tome usA Oh Aapee sep aip eee bedrest SECTORS PP MIAP DN PER PI BENTAN CR ETa WE piu ia La Criei i ai OFM y Sap Ore Pap ieee Tip weed bepari he beled bel eee lirar In mete Gate Fesi d a
6. en lower screw head removed with screwdriver Fig 17 Rod cut to correct length lower screw head can sometimes be unscrewed in the mouth without removing the appliance Fig 15 Another option A wire can be spot welded to the broken stem and then unscrewed Fig 16 272 Fig 19 Elastic placed distal to upper pivot and mesial to lower pivot to hold appliance together when patient opens wide 13 Rods coming out of the tubes Solution Ensure that the rods and tubes are long enough to prevent the appliance from disen gaging in the mouth Fig 17 To save chairtime the laboratory can cut and polish rods to the cor rect length 14 Rod impinging on the oral mucosa Solution Make sure the rod is not too long If the rod is causing a sore spot Fig 18 it must be shortened even if the appliance comes apart 15 Bent rods and split tubes The Herbst will normally come apart occa sionally but rods bend and tubes split when the appliance comes apart frequently If this occurs the patient should be seen as soon as possible because routine disengagement is the primary cause of loose and broken appliances JCO MAY 2002 Rogers Fig 20 When upper primary second molars are used for anchorage pivots should be moved about 2mm dis tally to prevent frequent disengagement ances Solution Make the rods and tubes longer If the rods cannot be lengthened because they would impinge on the cheeks and th
7. it in tap water The cement will simply flake off 7 Loose screws Solution Apply Ceka Bond to all screws to prevent them from unscrewing in the mouth Fig 7 8 Inadequate maxillary molar control Solution Do not use a transpalatal arch GC America Inc 3737 W 127th St Alsip IL 60803 Preat Corp Box 1030 Santa Ynez CA 93460 270 Fig 10 Sore spot from pivot impingement which can cause sore spots Fig 8 facilitate the development of crossbites and hinder maxillary arch expansion and molar rotation Without a transpalatal arch the molars are free to be expanded moved distally or rotated as needed for Class II correction 9 Archwire impinging on the oral mucosa Solution Cover the archwire with plastic tubing Fig 9 or closed coil springs to avoid sore spots If possible use at least an 018 stain less steel archwire to prevent breakage 10 Impingement on the ascending rami Solution Do not overadvance the mandible to the point that the Herbst pivots impinge on the ascending rami Fig 10 In severe cases it may not be feasible to advance to an edge to edge bite at first and a gradual advancement with shims JCO MAY 2002 praat Dro Fig 11 Cotton roll attached to appliance with elas tic to hold cheek away from pivot Fig 12 Screws covered with Comfort Caps extenders may be preferable Tip Placing the Herbst screw casing in the center or to the mesial of the
8. not be broken Tip A catalyst such as Zip Kicker or Zap available in hobby stores can be sprayed on the glue to set it up instantly Fig 2 Bands super glued in position in polyvinyl siloxane impression oP HREN MATA ea LFE O aces PLET est 1 i ibi imisa mi mii Fig 3 Midline deviation marked on laboratory pre scription JCO MAY 2002 p u 8 01 p 495 Dr Rogers is an Assistant Clinical Professor Department of Ortho dontics School of Dentistry Medical College of Georgia and in the pri vate practice of orthodontics at 3545 Wheeler Road Augusta GA 30909 E mail bracesmbr aol com 3 Midline overjet and overbite errors Solution Obtain an accurate wax bite reg istration and mark the laboratory prescription carefully to note the amount of advancement and any midline deviations Fig 3 This will reduce chairtime at appliance delivery because the rods and tubes will be cut to the proper length in the lab If the midline is off at appliance delivery advancement shims extenders can be added to Fig 4 Shim crimped in place with heavy wire cut ter Fig 5 This bicuspid will erupt slightly while Herbst is being fabricated VOLUME XXXVI NUMBER 5 correct the deviation The upper tubes may also be replaced to correct the midline as necessary Tip The shims should be crimped with a heavy wire cutter to prevent them from coming off and possibly being swallowed if the appliance disengages
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