Topics of the day:

1. Re: Biomechanics
2. RE: Scleroderma and orthodontics
3. RE: Slide Scanner
4. Re: Slide Scanner
5. Tongue thrusting in an adult patient
6. Posterior open bite tongue thrust
7. Lower expanders
8. Occlusal photos using Fuji S602 Zoom
9. ESCO - The Electronic Study Club for Orthodontics

 


From: "Rodrigo F. Viecilli" <philox@terra.com.br>
To: "'The Electronic Study Club for Orthodontics'" <ESCO@LISTSERV.UIC.EDU>
Subject: Re: Biomechanics
Date: Sat, 19 Jun 2004 13:30:01 -0300

Dear Dr. Kumaran,

For a general understanding of v-bend placement and loop comprehension, please look for the articles of the Professor of the Orthodontists you have mentioned: Dr. Charles J. Burstone. I'd recommend you to try to stay away from recipes for use of mechanical appliances of people that usually work for companies, not for Orthodontics. That won't help you very much in your understanding of biomechanics and will probably only increase your confusion.

A few comments:
1) If you want to have a more precise idea about the force system involved during space closure, you have to try segmented arch mechanics. If you use continuous arches it is too difficult to measure or predict the force system. There are studies showing force systems for segmented arches. A lot of people recommend a few methods for continuous arches but you will have to "believe them" and sometimes not in physics, since estimation of the force system for v bends in continuous arches is pretty difficult. Mulligan's method for cuspid retraction is effective if you do not bond brackets on the bicuspids. You need that interbracket distance. For evidence-based placement of v-bends for incisor retraction, it is more complicated because the arch has 3 dimensions and the classic article on v-bend placement can be applied correctly only to a straight wire. A student from Dr.Lindauer from Virginia Commonwealth University completed his thesis on this type of v-bend placement. I think the result is shown in one of the editions of Seminars in Orthodontics. V-bends placed on continuous arches tend to deformate the anterior part of the arch affecting second-order positioning. Take a look.

2) If you want to talk about T-loops for example, generally there are two methods for placement of V-bends. The first, simpler, is to use the v-bend incorporated on the loop itself (see the last Kuhlberg & Burstone article from 97 or the book Modern Edgewise Mechanics and the Seg. Arch Technique).

If you use this method, you position the loop asymmetrically in direction of the unit you want to keep stable (2-3 mm of asymmetry). I use this method when I start with a symmetrical loop and need more control in the end of space closure, when I reactivate the loop. The second method is to use the natural activation moment of the loop (that would configure a v-bend) together with a v-bend placed away from the loop. So you have a dynamic truncated v-bend as a result during space closure. In this method, you use a curved or acute v-bend near the unit you want to keep stable and the loop positioned near the active unit. This method is better if you want to control the anchorage since the beginning. For the rationale of the choice, wait for my article on this matter in the AJODO, which is on the Journal's line for publication, named "Self-corrective T-loop design for differential space closure".

After segmented arch space closure and root movement if necessary finishing can be performed with continuous arches.
If you need further discussion, there's a discussion group for biomechanics and seg. Arch that I moderate in yahoo, to subscribe send blank email to biosat-subscribe@yahoogroups.com We have united a lot of the people with scientific interest in controlled biomechanics (Dr. Burstone, Dr. Fiorelli, Dr. Siatkowski, Dr. Marcotte, Dr. Braun and others). I strongly recommend you to download the software LOOP from Demetrios Halazonetis at www.dhal.com (no commercial interest) With this software you can construct and simulate your own loops and get the force system you want.

Another option for the measurement of force system you can find in www.orthomeasurements.com (no commercial interest). I hope this helps.

Best regards,
Rodrigo F. Viecilli, CD, Ortho. Cert. (Brazil)
PhD Student- Indiana University/ Purdue University at Indianapolis
ICQ#: 1395648
"A man will be imprisoned in a room with a door that's unlocked and opens inwards; as long as it does not occur to him to pull rather than push it." Ludwig J.J. Wittgenstein

 


From: "Paul Thomas" <p.thomas@earthlink.net>
To: ESCO@LISTSERV.UIC.EDU
Subject: RE: Scleroderma and orthodontics
Date: Sun, 20 Jun 2004 14:07:16 +0100

Dear Brian,

I have treated two scleroderma patients (one focal one systemic), but more in the context of extractions for dental disease.  With systemic _expression, the perioral soft tissues *will not stretch* to any degree!    Instead they typically experience tissue tears at the commissures.  I can't imagine how you will be able to gain the physical access necessary to place anything on hte posterior teeth without soft tissue damage. I'm not sure about tooth movement, but I've treated other patients with systemic collagen disorders.  A quick look at the NLM show's there is precious little information related to orthodontics.  There is mention of abnormally widened PDM space.

Kindest Regards,

Paul M Thomas, DMD, MS
Senior Research Fellow:
Eastman Dental Institute
for Oral Healthcare Sciences
London, England



From: "Paul Thomas" <p.thomas@earthlink.net>
To: ESCO@LISTSERV.UIC.EDU
Subject: RE: Slide Scanner
Date: Sun, 20 Jun 2004 14:07:16 +0100

Dear Joe,

Dedicated slide scanners still tend to be a little pricey for the value received in occasional use.  Nikon sells a slide copying attachement which attaches to a number of their Coolpix cameras.  You would use a light box for the light source.  This does a credible job of duplicating and is faster than a scanner.  Likewise, you could do the same with a copystand/viewbox or tripod/viewbox arrangement after fabricating some type of cardboard jig to position the slide in the same position to copy with macro mode on the digital camera.  If you intent is to only have digital images for screen display, this will provide more than adequate resolution.  Here's an URL which discusses pros and cons.  http://www.andromeda.com/people/ddyer/photo/slide-transfer.html   I have found the tweaking necessary in Photoshop not that big a deal and not absolutely necessary unless you are being very picky.  The slide copy mode on the Coolpix 4500 adjusts contrast to avoid the "snappy" appearance.

I have owned both an early model Nikon Coolscan and a Polaroid Sprint Scan Plus. Both were extremely slow per slide scanned and the tech support was shakey for both. Now I figure I can adjust color/contrast if necessary on slides duped with camera and still spend less time than it took to scan.

Kindest Regards,

Paul M Thomas, DMD, MS
Senior Research Fellow:
Eastman Dental Institute
for Oral Healthcare Sciences
London, England



From: Scottdds@aol.com
Date: Mon, 21 Jun 2004 21:45:28 EDT
Subject: Re: Slide scanner
To: esco@listserv.uic.edu

Place your slides on a view box and photograph them with your digital camera.  You can buy a lens extension tube for your camera or even make one ( use the cardboard inner roll from paper towel or toilet paper) to eliminate light reflection from the view box on your lens.

 


From: "Albert Wong" <awong@netspace.net.au>
To: esco@listserv.uic.edu
Subject: Tongue thrusting in an adult patient
Date: Sun, 20 Jun 2004 06:08:48 -0700

Hi everyone,

I have an adult patient who had a mild-moderate bimaxillary dental protrusion and consequent spacing of the anterior teeth.  I have treated her by retracting the anteriors and fitted her with bonded upper and lower lingual retainers.  However, she reports that she still feels her tongue pushing against the anterior teeth, particularly at night.  Indeed, there are indentations on the tip and lateral surfaces of her tongue, and slight spacing between her upper incisors.  I would like to hear from other orthodontists on ways to manage the tongue - is there a night-time appliance that could help hold her tongue away from her teeth?  When is tongue reduction surgery needed and is it successful?  Any other suggestions?

Many thanks,
Albert Wong
Orthodontist
Victoria, Australia

 


Date: Wed, 23 Jun 2004 11:42:00 -0700 (PDT)
From: "Dr. Rob van den Berg" <drv@sbcglobal.net>
Subject: Posterior open bite tongue thrust
To: esco@listserv.uic.edu

We have an 18 YO patient with a bi-lateral posterior open bite, apparently due to habitual tongue placement between the teeth. All of the function takes place on the upper and lower 3-3, and the posterior bite is progressively more open starting at the bi's, with the second molars separated by about 6 mm. The patient relates holding the tongue between the teeth at all times, except at night time when he wears a tongue guard retainer with spurs that keep the tongue away from the dentition. The patient had phase I and phase II orthodontic treatment as a teenager after which the posterior bite was more closed than  it is now. The posterior open bite appears to be secondary to the tongue postion, rather than due to a primary eruption defect. Skeletal pattern is Class III due to maxillary retrognathia, dental compensations were added during the orthodontics to create a small but positive overjet and overbite.

The anterior teeth are starting to show signs of parafunction and occlusal trauma, most notably gingival recession on all four cuspids. The goal is to provide a definitive solution to this problem, with good function and a stable occlusal result.

At this point we are considering a variety of options including orthognathic surgery, tongue reduction, tongue position training. I am seeking to hear from clinicians that have treated patients with a similar problem. Actual cases describing your patient, the treatment and the level of success short and long term would be most helpful.

Rob van den Berg, DDS, MS
San Ramon, CA

 


From: ATogrye@aol.com
Date: Wed, 23 Jun 2004 19:42:21 EDT
Subject: Lower expanders
To: ESCO@LISTSERV.UIC.EDU

Dear colleges:

I occasionally have a problem with lower expanders turning back or loosening up. I realize some may not use lower expanders, but for those who do, does this happen to you? I never see it with my upper expanders. Specialty lab in Atlanta has come up with a new screw that does not turn back. I also sometimes place band lock or an adhesive that will stick to metal on the threads to prevent it from turning back. Any suggestions would be appreciated.

Anthony Togrye
Tennessee

 


Date: Sat, 19 Jun 2004 13:00:55 -0400
To: esco@listserv.uic.edu
From: "Susan Eslambolchi" <susan.eslambolchi@rogers.com>
Subject: Occlusal photos using Fuji S602 Zoom

I've recently started taking occlusal photographs using my Fuji S602Zoom (special edition). For regular intraoral photos, I've been using F11 and ISO 125 and the macro lens. But I'm finding the occlusal shots are coming out quite dark. Is there anyone else on the list using this camera for occlusals? If yes, I would love to know what the correct settings are for occlusal shots.

Thanks in advance,
Susan Eslambolchi
Toronto, Canada



 

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