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Biomedical subjects

Peter R Diedrich

Publications and source records attributed to Peter R Diedrich.

9 recordsLinked to original sources
PubMed2006

Biomechanics of a modified Pendulum appliance--theoretical considerations and in vitro analysis of the force systems.

The aim of this study was to analyse the acting forces and moments induced by a special orthodontic appliance, the Pendulum K, for molar distalization in the transverse and sagittal planes. The purpose-designed test set-up (artificial maxilla with anchorage unit and two electrothermodynamic molars, an electronic measuring unit, a unit with force-moment sensor, an analogue/digital converter, and a data read-out unit) allowed simulation of in vivo conditions on the one hand and precise determination of the force systems on the other. The appliances investigated were three specimens of the Pendulum K. In vitro measurement of the resulting force systems revealed that the forces and moments in the transverse and sagittal planes remained almost constant over a 3 mm measuring increment when the distal screw was continuously activated (10 activations/mm). Without reactivation of the incorporated distal screw, however, a marked decline in the force systems was recorded. The Pendulum K allows translatory distalization of the upper molars and thus dental arch expansion, dispensing with the need for permanent teeth to be extracted, subject to a corresponding indication. This is achieved by continuous adjustment of an incorporated distal screw and by specific pre-activations of the Pendulum springs.

Biomechanical Phenomena↗
PubMed2006

Molar distalization with pendulum appliances in the mixed dentition: effects on the position of unerupted canines and premolars.

INTRODUCTION: The pendulum appliance allows for rapid molar distalization without the need for patient compliance. Its efficiency has been confirmed in a number of clinical studies. However, the potential interactions and positional changes between the deciduous molars used for dental anchorage and the erupted and unerupted permanent teeth have yet to be clarified when this appliance is used for molar distalization in the mixed dentition. METHODS: Twenty-nine patients in the mixed dentition each received a modified pendulum appliance with a distal screw and a preactivated pendulum spring for bilateral distalization of the maxillary molars. The patients were divided into 4 groups based on dentition stages: patient group 1 (PG 1, n = 10) was in the early mixed dentition; patients had resorption of the distal root areas of the deciduous molars being used for dental anchorage, and the unerupted premolars were located at the distal margin of the deciduous molar root region. Based on radiographs taken before placement of the pendulum appliance, patient group 2 (PG 2, n = 10) was diagnosed as having a central location of the unerupted premolars. In the third group (PG 3, n = 4), the first premolars were already erupted and could be integrated into the dental anchorage, but the canines were not yet erupted. In the fourth group (PG 4, n = 5), the first premolars and both canines were fully erupted. RESULTS: Statistical analysis of the measured results showed significant differences in the side effects between PG 1 and PG 2. In patients being treated with pendulum appliances, the anchorage quality of the deciduous molars that were already partially resorbed in the distal root area was comparatively reduced. Consequently, the mesial drift of the deciduous molars and incisors was increased, without impairing the extent and quality of the molar distalization. Anchorage loss in the supporting area had no direct impact on the sagittal position of the unerupted premolars in the early mixed dentition. CONCLUSIONS: If permanent teeth have already started to erupt in the supporting area, additional space restrictions should be avoided in patients with critical topography, especially if there is little space for the unerupted canines. At this stage of the mixed dentition, premolar extraction or augmentation of the supporting area with extraoral headgear offers a therapeutic alternative to intraoral distalization appliances with exclusively dental anchorage.

Analysis of Variance↗
PubMed2006

[Uprighting of a tipped lower second molar with the aid of a microscrew anchorage. A case report].

Titanium microscrews for orthodontic anchorage purposes have been developed in different designs and dimensions by a number of manufacturers. Whereas conventional implants need a relatively extensive bone supply and the insertion sites are limited, microscrews offer a more flexible range of applications. They also offer crucial advantages such as simple, atraumatic insertion and removal, a minimum patient stress and a favourable cost-benefit ratio. In the present case report the successful orthodontic uprighting of a tipped second lower molar using a microscrew demonstrated.

Adolescent↗
PubMed2005

Anchorage quality of deciduous molars versus premolars for molar distalization with a pendulum appliance.

PURPOSE: The aim of this study was to assess dental anchorage qualities when the pendulum appliance is used for distal molar movement. MATERIAL: Thirty adolescents in various dentition stages received a modified pendulum appliance with a distal screw and a specially preactivated pendulum spring for bilateral molar distalization in the maxilla. The subjects were subcategorized into 3 groups of 10 according to the dental anchorage used: deciduous molars, premolars and deciduous molars, or only premolars. Dentoalveolar effects and side effects in the anchorage unit and in the molar area were determined by cephalometric analysis. RESULTS: Statistical analysis of the measurements showed significant differences between groups in the extent of molar distalization and the resulting incisor protrusion. Distal tipping of the 6-year molars was significantly less severe (2.3 degrees +/- 1.58 degrees to the palatal plane and 2.55 degrees +/- 1.52 degrees to the anterior cranial base) in patients with premolar anchorage than in those with deciduous molar anchorage (6.15 degrees +/- 3.42 degrees and 6.35 degrees +/- 3.46 degrees ). Incisor protrusion was significantly more pronounced in patients with deciduous molar anchorage (2.75 +/- 1.4 mm) than in the other 2 groups (1.65 +/- 0.82 mm, mixed deciduous molar and premolar anchorage, and 1.75 +/- 0.75 mm, premolar anchorage). Additionally, incisor protrusion was translatory compared with controlled tipping in subjects with deciduous molar anchorage or premolar and deciduous molar anchorage. CONCLUSIONS: Deciduous molars and premolars can be used for anchorage for molar distalization with a pendulum appliance; however, anchorage with premolars only results in the least pronounced dentoalveolar side effects. The anchorage quality of deciduous molar and mixed deciduous molar/premolar anchorage is limited.

Adolescent↗
PubMed2005

Molar distalization with a modified pendulum appliance--in vitro analysis of the force systems and in vivo study in children and adolescents.

The standard pendulum appliance was modified by integrating a distal screw into its base and by special preactivation of the pendulum springs. The suitability of this Pendulum K for the translatory distalization of maxillary molars was investigated in an in vitro analysis and in an in vivo study in children and adolescents. The in vitro measurement of the resulting force systems revealed that all forces and moments remained virtually constant over a three-mm simulated distalization increment. The transverse force, Fx, increased from two to 11 cN and the weakly intrusively acting force, Fy, from six to eight cN, but these increases were not statistically significant. The distalization force, Fz, initially 201 cN, was still 199 cN after a three-mm distalization increment. The mesially acting moment, My, rose from 1654 to 1834 cN mm, whereas the palatally acting moment, Mz, declined slightly from 229 to 164 cN mm. The slight, consistent distoinclinatory moment, Mx, initially 306 cN mm, was 310 cN mm after three mm. In parallel, the in vivo study with its collective of 66 patients confirmed that the Pendulum K allows a virtually translatory molar distalization with slight tippings of 4.75 degrees to the palatal plane and 4.25 degrees to the anterior basal plane. Palatal movements of the first molars were avoided. The proportion of molar distalization in the total movement was 73.53%.

Adolescent↗
PubMed2004

Efficiency of a pendulum appliance for molar distalization related to second and third molar eruption stage.

A modified pendulum appliance, including a distal screw and special preactivated pendulum springs (built-in straightening activation and toe-in bending), was used for bilateral maxillary molar distalization in 36 adolescent patients in various stages of the molar dentition. The patients were divided into 3 groups (PG 1-3) according to the stage of eruption of their second and third molars. In PG 1 (18 patients), eruption of the second molars had either not yet taken place or was not complete. In PG 2 (15 patients), the second molars had already developed as far as the occlusal plane, with the third molars at the budding stage. In PG 3 (3 patients), germectomy of the wisdom teeth had been carried out, and the first and second molars on both sides had completely erupted. Analysis of cephalograms to identify any changes in the sagittal plane showed that, in the direction of distalization, a tooth bud acts on the mesial neighboring tooth like a fulcrum, and that tipping of the first molars in patients in whom the second molar was still at the budding stage was thus greater. In patients whose second molars had erupted completely, the degree of tipping was greater again when a third molar bud was located in the direction of movement. After previously completed germectomy of the wisdom teeth, almost exclusively bodily distalization of both molars is possible, even without bands being applied to the second molars. However, if the first and second molars are distalized simultaneously with a pendulum appliance, the duration of therapy will be longer, greater forces will have to be applied, and more anchorage will be lost. Statistical analysis of the results of dental-angular measurements showed significant differences in the degree of molar tipping and reciprocal incisor protrusion. The degree of distal tipping of first molars was less in patients with erupted second molars (PG 2 and PG 3) than in those whose second molars were not yet erupted (PG 1). For instance, the measured angles were 0.9 degrees +/- 3.43 degrees (to the palatal plane) and 0.8 degrees +/- 3.4 degrees (to the anterior cranium floor) in PG 2, and -0.33 degrees +/- 0.58 degrees and 0.67 degrees +/- 2.08 degrees, respectively, in PG 3, contrasting with respective values of 5.89 degrees +/- 3.74 degrees and 5.36 degrees +/- 3.49 degrees in PG 1. Tipping of erupted second molars was much more marked in PG 2 (7.92 degrees +/- 5.83 degrees to the palatal plane and 7.55 degrees +/- 5.28 degrees to the anterior cranium floor), but much less pronounced in PG 3 (2 degrees +/- 1.73 degrees to the palatal plane and 2 degrees +/- 2 degrees to the anterior cranium floor) than the corresponding movement of the second budding-stage molars in PG 1 (4.06 degrees +/- 2.15 degrees and 3.97 degrees +/- 2.27 degrees, respectively). The degree of incisor protrusion occurring reciprocally with molar distalization was much less in these patients (measured angles of 3.28 degrees +/- 1.97 degrees and 2.89 degrees +/- 2.17 degrees to the palatal plane and anterior cranium floor, respectively) than in the patients presenting different stages of the dentition (angles of 5.5 degrees +/- 3.33 degrees and 6.03 degrees +/- 4.29 degrees, respectively, in PG 2, and angles of 5.5 degrees +/- 3.28 degrees and 6.67 degrees +/- 3.09 degrees, respectively, in PG 3). Moreover, measurement of dental casts in the horizontal plane showed not only the targeted mesiobuccal rotation of both maxillary molars, but also a vestibular drift of the unbanded second molars.

Activator Appliances↗
PubMed2003

Orthodontic fine adjustment after vertical callus distraction of an ankylosed incisor using the floating bone concept.

The outcome of vertical callus distraction of a segment of tooth-supporting alveolar process might be functionally and esthetically unsatisfactory because of the unidirectional impact of intraoral distraction devices. In this case report, we describe how, with a shortened consolidation phase and application of the floating bone effect, the tooth-supporting osteotomy segment can be successfully aligned 3 dimensionally. We applied orthodontic force systems that went beyond the unidirectional vector preset by the mechanical properties of the distraction device.

Alveolar Process↗