The influence of a 0.2% chlorhexidine mouthrinse on plaque regrowth in orthodontic patients

In a prospective plaque regrowth study focusing on oral hygiene during fixed appliance therapy 12 adolescent patients (mean age 14.1 +/- 1.5 years) were evaluated twice over 2-day test periods. In the randomized, double-blind study the influence of a 0.2% chlorhexidine (CHX) mouthrinse (Corsodyl) and a commercially available dentifrice supplementing fluoride (Odol-med-3) were compared intra- and interindividually in a crossover design with regard to plaque and gingivitis. Before starting the first test phase there was a 14-day preliminary phase for upgrading the oral hygiene. Between the 2 test phases was a 5-day "washout". On the last day of the second test phase the patients were asked to fill in a questionnaire concerning their experiences during the study. The 0.2% Corsodyl reduced the plaque index scores significantly (p < 0.001). The gingival index revealed a similar reduction (2nd day of test: p = 0.03). Until the 5th day of washout a clear-cut carryover effect of the chlorhexidine rinse on the gingival index was observed. Both the lower mean values of the 2 clinical parameters at the beginning of the test phases as compared with those at the beginning of the preliminary phase and the evaluation of the questionnaires indicated a possible Hawthorne effect. 0.2% Corsodyl may be employed as an adjunct to other preventive measures such as professional care and patient-oriented instruction on an intermittent basis in order to reduce the plaque-induced iatrogenic side effects and to enhance the efficacy of oral hygiene measures in connection with orthodontic therapy with fixed appliances.     

Torque Deformation Characteristics of Plastic Brackets: A Comparative Study

AIM: The purpose of this study was to compare the torque deformation characteristics of seven commercially available plastic brackets, both amongst each other and with stainless steel brackets. MATERIAL AND METHODS: Ten brackets each of (1) pure polycarbonate, (2) ceramic reinforced polycarbonate, (3) fiberglass reinforced polycarbonate, (4) ceramic reinforced polycarbonate with metal slot, (5) fiberglass reinforced polycarbonate with metal slot, (6) polyurethane, and (7) polyurethane with metal slot were exposed to torsion in a torquemeter, following an aging process according to ISO 10477. Ten stainless steel brackets served as a control group. Torsion was applied continuously using a material testing machine (Zwick Z2.5, Zwick Materialprüfung, Ulm, Germany). RESULTS: The results showed within the group of plastic brackets that metal slot reinforced brackets were subject to the lowest degree of deformation, followed by the brackets made of pure polyurethane, pure polycarbonate and fiberglass reinforced polycarbonate. The ceramic reinforced polycarbonate brackets showed the highest deformation under torque stress. The plastic deformation of the ceramic reinforced, fiberglass reinforced and pure polycarbonate brackets started even in the recommended torque range of 10-20 Nmm. The additional ceramic and fiberglass in the plastic brackets investigated in this study did not improve the torque stability of the polycarbonate brackets. The pure polyurethane brackets showed no significant difference from the pure polycarbonate brackets at the moment of 15 Nmm which is the optimal torque for a maxillary incisor. CONCLUSION: A comparison with the stainless steel brackets illustrated that plastic brackets are suited for clinical application only if they have a metal slot.     

Various Anchorage Approaches in Unilateral Mandibular Molar Distalization Using a Fixed Lingual Arch Appliance

PATIENTS AND METHOD: Mean unilateral mandibular molar distalization of 3.33 +/- 1.28 mm was achieved in 20 patients (average age: 13 years, 1 month) by fitting an asymmetrically activated lingual arch appliance for an average treatment period of 4 months. Three different anchorage techniques were used: Anchorage was provided in seven patients by the lingual arm of the appliance alone, while another seven patients received additional sectional archwires, and another six patients sectional archwires and lip bumpers. RESULTS AND DISCUSSION: Anchorage by means of the lingual arm alone proved to be insufficient to prevent labial tipping of the incisors. The mean protrusion and labial tipping recorded at the lower incisors was 7.67 degrees +/- 1.53 degrees and 2.64 +/- 0.48 mm respectively. The anchorage quality was enhanced and satisfactory stabilization achieved by additionally inserting a sectional archwire. In these cases the mean incisor protrusion and labial tipping was 1.75 degrees +/- 0.96 degree and 0.71 +/- 0.76 mm respectively and thus significantly lower (p < 0.01). The additional fitting of a lip bumper provided no further increase in anchorage quality (incisor protrusion 1.75 degrees +/- 2.87 degrees and 0.67 +/- 1.21 mm respectively). CONCLUSION: Fitting additional anchorage aids appears to have no direct impact on the extent and quality of molar distalization.     

Beanspruchungsuntersuchungen an Rekonstruktionsplatten zur Überbrückung von Kieferwinkeldefekten

Aim

The aim of the present study was to evaluate the mechanical stress in reconstruction plates used for bridging mandibular angle defects and in the screw-plate-bone interface with the finite element method. Additionally, the influence of reconstruction plate geometry, screw configuration, and screw diameter upon the mechanical stress distribution was determined. Suggestions for design improvements of the plate were derived from the results.

Material and methods

Based on the geometrical data of a human mandible, an angle defect bridged by a titanium reconstruction plate was generated and exposed to chewing force. The reconstruction plate was securely fixed by M 2.7 titanium screws. A variation of plate design, screw configuration, and screw diameter was carried out. The mechanical stress was calculated following the von Mises stress hypothesis.

Results

Using the standard plate the mechanical stress in all components exceeded by far the ultimate tensile strength. Possible clinical consequences could be a fatigue fracture of the plate, loosening of the screw, and irreversible damage of the bone leading to infection. Increasing the screw diameter by 50% would lead to a decrease of the mechanical stress by far more than 50%. An increase of the interface area between bone and plate and a triangular screw configuration diminishes the mechanical stress further, which may consequently allow a reduction of plate thickness with better adaptation to the actual jaw geometry.

Conclusion

As a preliminary result the reconstruction plate could be thinned out in areas subject to less mechanical load.     

Kiefergelenkbeschwerden bei juvenilen Patienten mit rheumatischen Erkrankungen

Fragestellung

Ziel der Untersuchung war es, die Häufigkeit von klinischen Kiefergelenkbeschwerden bei Kindern mit rheumatischen Erkrankungen zu erfassen und Zusammenhänge zwischen dem Stadium der rheumatischen Erkrankung und dem klinischen Bild einer Kiefergelenksymptomatik zu evaluieren.

Material und Methodik

Im Rahmen einer prospektiven Untersuchung wurden die Kiefergelenke von 48 Kindern mit einer rheumatischen Erkrankung klinisch untersucht. Folgende Parameter wurden evaluiert: Knacken, Reibegeräusche, Druckdolenzen, Dauer der rheumatischen Erkrankung sowie die Anzahl der betroffenen peripheren Gelenke. Das Stadium der rheumatischen Erkrankung wurde mit Hilfe der Steinbrocker-Klassifikation erfasst.

Ergebnisse

Insgesamt wiesen 26 Patienten (54,17%) eines oder mehrere der o. g. Kiefergelenksymptome auf. Der Chi-Quadrat-Test ergibt keine signifikanten Zusammenhänge zwischen dem Grad der Steinbrocker-Klassifikation und dem Auftreten pathologischer Befunde am Kiefergelenk. Eine erhöhte Anzahl der von der rheumatischen Erkrankung betroffenen Gelenke führt nicht zu einem signifikanten Anstieg von pathologischen Kiefergelenkbefunden. Es zeigt sich jedoch ein signifikanter Zusammenhang zwischen der Erkrankungsdauer und dem Auftreten pathologischer Kiefergelenkerscheinungen. Knack- und Reibegeräusche kommen mit zunehmender Erkrankungsdauer signifikant häufiger vor (p=0,011).

Schlussfolgerung

Kinder mit rheumatischen Erkrankungen neigen häufiger zu Kiefergelenkerkrankungen als Kinder ohne rheumatische Erkrankungen. Mit Fortdauer der rheumatischen Erkrankung steigt die Inzidenz pathologischer Kiefergelenksbefunde.     

Psychische Determinanten der Mitarbeit kieferorthopädischer Patienten — ein Beitrag zur Frage der Kooperationsprognose

Zusammenfassung In einer umfangreichen Untersuchung wurden Patienten, die nach Einschätzung ihrer Behandler in der kieferorthopädischen Behandlung besonders gut mitarbeiteten, solchen gegenübergestellt, die besonders schlecht mitarbeiteten. Dabei wurde ein psychodiagnostisches Instrumentarium verwendet, dessen Einzelverfahren so ausgewählt waren, daß sie sich für Kinder und Jugendliche eigneten und daß der erfaßte Inhalt etwas mit Kooperationsbereitschaft, Pflichteifer, Gewissenhaftigkeit und Ausdauer zu tun haben könnte. Es ergaben sich mehrere signifikante Unterschiede. Aufgrund der vorliegenden Ergebnisse kann der Typ des nichtkooperativen Patienten beschrieben werden.

---

Summary A large scale study was conducted in which orthodontic patients, who were rated as highly cooperative in treatment were compared to uncooperative patients. The specific psychological diagnostic tests were chosen to be suitable for children and adolescents and to reflect cooperation, responsibility, reliability and endurance. A number of significant differences could be found. The results enable one to describe the type of uncooperative patient.

---

Résumé Dans une étude approfondie, on a comparé lors de leur traitement orthodontique, des patients qui ont été particulièrement coopératifs avec ceux qui l'étaient moins. Pour cela, on a utilisé un procédé diagnostique psychologique, choisi pour être adaptable aux enfants et aux adolescents et dont l'analyse reflète la coopération, le zèle, la responsabilité et la persévérance. Il en résulte plusieurs différences significatives. Il permet aussi de décrire le type du patient non-coopératif.

---

---

Vortrag, gehalten auf der Jahrestagung der Deutschen Gesellschaft für Kieferorthopädie 1985 in Mainz.     

Iatrogene Funktionsstörungen der Kiefergelenke

Zusammenfassung Häufiger bekannt sind Funktionsstörungen des stomatognathen Systems nach prothetischen, zahnärztlich-chirurgischen oder kieferchirurgischen Eingriffen. Aber auch gewisse kieferorthopädisch-orthodontische Maßnahmen können mit dem Auftreten von Funktionsstörungen während einer kieferorthopädischen Behandlung in Zusammenhang gebracht werden. Alle angeführten Fallbeispiele zeigten vor einer kieferorthopädischen Behandlung einen unsymptomatischen Gelenkbefund. Beispiele von iatrogenen Funktions-störungen wie Diskusverlagerungen mit oder ohne Gelenkknacken werden aufgezeigt. Eine Tabelle von Behandlungsmodalitäten mit gewissem Risiko für Funktionsstörungen wird besprochen.

---

Summary There are different causes for functional disturbances of the temporomandibular joint, such as loss of teeth or surgical intervention. However, orthodontic cases may have latent pre-existing conditions, which may be provoked as a result of treatment. All patients shown had no signs or symptoms of TMJ involvement prior to orthodontic treatment. Examples of orthodontically induced TMJ dysfunction are shown, such as internal derangement, with or without reduction. A list of treatment modalities that may produce TMJ problems during treatment is presented.

---

Résumé On note assez frequemment des perturbations fonctionnelles du système stomatognathique après des traitements prothétiques, dento-chirurgicaux ou maxillo-chirurgicaux. En plus, certains actes orthodontiques peuvent causer des perturbations fonctionnelles pendant un traitement orthodontique, car dans les cas sus-mentionnés aucun patient ne présentait une symptomatologie pathologique de l'articulation temporo-mandibulaire avant le traitement orthodontique. On a trouvé des exemples de perturbations fonctionnelles iatrogènes comme des déplacements de disque avec ou sans craquement articulaire. Enfin, on a établi un tableau indiquant les modalités de traitement impliquant un certain risque de causer des perturbations fonctionnelles.

---

---

Vortrag bei der wissenschaftlichen Jahrestagung der Deutschen Gesellschaft für Kieferorthopädie im Mai 1986 in Regensburg.     

Patient Evaluation of Treatment with Fixed Prostheses Supported by Implants or a Combination of Teeth and Implants

PURPOSE: The objective of this study was to compare treatment outcomes among subjects with complete arch fixed prostheses in the maxilla, supported by implants or a combination of natural teeth and dental implants. MATERIALS AND METHODS: Twenty-one subjects with maxillary tooth- and implant-supported fixed prostheses and 21 subjects with maxillary implant-supported fixed prostheses were identified and included in the study. All abutment teeth in the group with tooth- and implant-supported prostheses were provided with cemented copings that incorporated threads for vertical locking screws. Frameworks were fabricated with a gold alloy that was veneered with acrylic resin or ceramic materials. All frameworks were screw-retained to implants and copings. Frameworks in the group with implant-supported prostheses were fabricated with milled titanium or gold alloy to which denture teeth and resin base material were applied. All prostheses had a minimum of 8 units, at least 4 of which were in one quadrant. Subjects in both groups were mailed a questionnaire consisting of 15 questions focused on various factors related to treatment outcome, such as oral function and patient satisfaction. RESULTS: The response rate was 86%. Both groups reported a high satisfaction rate for most items with few regretting their choice of treatment. Most individuals in both groups reported great improvement in chewing ability and few reported phonetic disturbances. No statistically significant differences were found between the groups. CONCLUSION: The results of the present study showed similarity in questionnaire responses between the 2 groups of participants. High satisfaction was reported both among subjects who received a complete arch fixed prosthesis in the maxilla supported by dental implants only, as well as among those whose prostheses were supported by a combination of natural teeth and dental implants.