The GDR (Gouttière Dentaire à Rampe) can be viewed as a soft monobloc with a buccal shield and a facebow mainly intended for oral stability, which means a triple action: mechanical, functional and orthopedic.
Actually, it can act as a mechanically designed appliance, thanks to its buccal shield that exerts a light pressure on maxillary anterior teeth for easy alignment. Considering its design - reminding us of Demosthenes' famous stone - the GDR can also be a full functional appliance in the widest sense of the term as, when retraining orofacial functions (breathing and swallowing), it restores a harmonious shape of the manducatory tract.
This is a special application of Lamarck's global theory, unfortunately summarized in a wrong but famous quote "function creates the organ", although shape-function relationships are very complex and need much deeper thinking.
As far as we are concerned, the GDR - like most functional devices - acts mainly through :
• Obstacles removal
For instance, in a severe classical Class II,1 case with an anterior deep bite, a lower lip interposition at rest and during function, thumb sucking and visceral swallowing, using a GDR will allow:
• A mandibular release through vertical unlocking.
• An incentive to self-managed mandibular protrusion, which will make normal growth and nasal breathing start anew.
• The removal of the lower lip interposition between upper and lower incisors.
• The guidance of the tongue and lips that will induce a behavioral evolution in a positive way toward adult swallowing and full nasal breathing.
As the GDR can be described as a soft monobloc, its spectacular orthopedic results logically are the same as those Pierre Robin already reported long ago. Like Robin's monobloc, the GDR generates a mandibular protrusion thanks to the bulge it gives its name to. The difference is it allows a comfortable progressive self-regulated adaptation, when the monobloc is rigid and immediately asks for a mandibular hyper protrusion, often painful and difficult to get when the discrepancy is severe.
General and maxillo-facial orthopedic results obviously match those of the eumorphic theory that will translate into morphogenetic harmony theory, i.e.: dental and skeletal relationships harmonize from Class II to Class I (see case). This antero-posterior harmonization most often comes with a restoration of a proper overbite, whatever the initial condition was: overbite or openbite.
Considering general orthopedics - which certainly is the best domain of benefits from mandibular protrusion - the harmonization of the maxillomandibular relationship always comes with (cause or consequence?) a restoration of nasal breathing and a definite improvement of ventilation.
As any breathing body is straightening, users of mandibular protruding devices all appreciated their benefits to the general posture, physical (including a straightening of the spine) and psychological.
Post-treatment cephalometric analysis shows - as in any comparable treatments - that the antero-posterior skeletal relationships improved, with a possible variation the in vertical relationship, but always in a positive way.
As for alveolar relationships, they, of course, tend to normalize (I-F i/ma) or to participate to the compensation of the skeletal discrepancy.
On a strictly technical point of view, the GDR has numerous advantages over the monobloc "easy to make, but difficult to make a success of".
As a matter of fact, it suppresses the necessity of an edge-to-edge bite registration that is always tricky and difficult to reproduce in the lab.
• It is compatible with mouth breathing.
• It is compatible with the shedding of deciduous teeth and with the evolution of permanent teeth, without any adjustment.
• It is compatible with fixed appliances.
• Then, as previously mentioned: it is a soft appliance like the original Monobloc and at the opposite of current monoblocs.
All reflections lead to think that GDR's indications are far from being exhausted, and that it could be an appliance with numerous individual or cumulative effects that could be of good use in many cases in the mixed and permanent dentition, after a careful study of the case.
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