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.     

Band and loop space maintainer--made easy

Space maintainers have been used in Pediatric Dentistry for many years. The use of these appliances, however, in terms of indications, contraindications, design and construction has gained little attention from researchers. This paper highlights the construction of a new technique of fabrication of band and loop space maintainer. The advantages of this new Direct technique or Single sitting technique over the conventional technique are discussed.     

Er:YAG laser osteotomy directed by sensor controlled systems

BACKGROUND: Great efforts have been taken in the past to develop laser systems suitable for bone cutting. Laser systems emitting light in the infrared spectrum (2.9, 3.0 microm) have been found to be ideal for efficient bone ablation with very little carbonization. AIM: To evaluate a new laser bone cutting system enabling the automatic detection of different tissue qualities by an integrated sensor to avoid damage to sensitive structures such as blood vessels or nerves. MATERIAL: An Erbium:YAG laser containing an integrated closed-loop control system, was constructed and tested on dissected bone. Process emissions such as resonance changes caused by the interaction of laser light and various tissue structures can be used for a controlled system. Sensor signals from a photodiode and a piezo-electric accelerometer were received and processed to guide the laser osteotomy. METHODS: Tests were performed on dissected bone specimens from rabbit femur (14) and minipig jaw (6). After laser application, the bone specimens were evaluated macroscopically and histologically. RESULTS: The specimens were evaluated histomorphometrically for the depth of cortical bone ablation when the closed-loop control system switched off the laser. Mean courses of 97.45% (pig) and 97.83% (rabbit) showed that the systems work with precision. CONCLUSION: After penetrating the cortical bone layer, the laser beam was promptly interrupted due to extreme changes of the signal character received by the sensor system. The in vitro tests of this new laser closed-loop control system were successful.     

Resorbable and nonresorbable hydroxyapatite granules as bone graft substitutes in rabbit cortical defects

Background: The use of various synthetic calcium phosphate compositions for the promotion of bone in bone defects is of potential interest because such materials may be tailor made and may bond to bone. There is yet an inadequate knowledge of the role of calcium phosphate composition and resorbability for the bone response. Purpose: The aim of the present study was to compare the ability of resorbable versus nonresorbable hydroxyapatite (HA) granules to promote new bone formation in cortical bone defects. Resorbable and nonresorbable HA granules, used as bone graft substitutes, were evaluated after 6 weeks and 3 months in the rabbit tibia. Circular defects (diameter 5.0 mm) were made in both tibias of 18 New Zealand white rabbits. The 36 defects were divided into three groups (six observations per group and time, respectively). The first group was augmented with resorbable HA granules, the second group was augmented with ceramic nonresorbable HA granules, and the third group was left without augmentation (control). The animals were killed after 6 weeks and 3 months, and the tissue was evaluated with light microscopic (LM) morphology and morphometry, scanning electron microscopy (SEM), and energy dispersive x‐ray analysis (EDX). Results: After 3 months LM morphometry revealed significantly more newly formed bone in the two HA augmented groups compared with that in the control. A close contact was found between both kinds of HA granules and new bone as viewed with light microscopy and SEM. A relatively slow degradation process was indicated by the small reduction of the total granule area in the cortical defects. However, LM observations showed a change of granule form. Pilot experiments using SEM‐EDX indicate that Ca and P contents had decreased in the resorbable HA granules between 6 weeks and 3 months. Further, a higher content of Ca and P was found in the newly formed bone close to granules, in comparison with more distant newly formed bone. Conclusions: Our results suggest that both resorbable and nonresorbable HA granules promote new bone formation in rabbit cortical defects, which does not occur in control defects.     

Restoration of irradiated patients using osseointegrated implants: Current perspectives

Statement of problem. The success rates of osseointegrated implants used to restore patients who were irradiated for head and neck tumors are influenced by radiation-induced changes in the hard and soft tissues.Purpose. This article examined, by review of the literature, current perspectives on the restoration of irradiated patients using osseointegrated implants.Results. In published reports that investigated both intraoral and extraoral applications, irradiation decreased implant success rates and the amount of reduction was dependent on the location within the craniofacial skeleton. The limited number of implants and patients in these studies precludes definitive conclusions regarding the efficacy of placing implants into irradiated tissues. The implants placed into the irradiated anterior mandible have demonstrated an acceptable implant success rate of 94% to 100% with a minimal risk of osteoradionecrosis. The efficacy of implants in the posterior mandible has not been examined. Implant success rates ranged from 69% to 95% in the irradiated maxilla for intraoral applications. Extraoral applications demonstrated excellent implant success rates in the temporal bone (91% to 100%). The rates in the anterior nasal floor have varied from 50% to 100%. The implant success rates in the frontal bone decreased as the length of the studies increased (96% to 33%). The long-term efficacy of implants in the irradiated frontal bone is poor. (J Prosthet Dent 1998;79:641-7.)     

T-lymphocyte subsets in recurrent aphthous ulceration

Peripheral T-lymphocyte subsets: T-helper (OKT4) and T-suppressor (OKT8) cells were studied quantitatively in 20 patients with recurrent aphthous ulceration (RAU) in ulcerative, as well as inactive, stages of the disease. The figures were compared with T-lymphocyte subsets from matched control donors with no history of RAU. The ratio of T-helper: T-suppressor cells was significantly lower in both stages in the patients compared with controls due to a significantly increased number of T-suppressor cells in RAU patients. The number of T-helper cells in the patients did not differ significantly in either stage compared with controls. The study support the hypothesis of recurrent aphthous ulceration being a disorder of immunodeficiency.     

Combined Therapy with Pendulum and Lingual Arch Appliances in the Early Mixed Dentition

PATIENTS AND METHOD: In 20 patients with arch length deficiency and anterior crowding, pendulum and lingual arch appliances were inserted simultaneously in the upper and in the lower arch respectively to gain space. The patients were divided into two groups according to their dental eruption stage: ten children (six boys, four girls; mean age: 9 years, 6 months) were in the early mixed dentition, while an adolescent comparison group of the same size (three boys, seven girls; mean age: 12 years, 3 months) were in the permanent dentition at the beginning of treatment. AIM: The main purpose of the study was to investigate whether simultaneous therapy with pendulum and lingual arch appliances is to be recommended, i.e. whether this therapy should take place as interceptive treatment in the early mixed dentition or only in the permanent dentition in adolescence. Parameters were the extent and quality of dentoalveolar effects and the side effects (mesial movement of the incisors, protrusion of the incisors, tipping of molars). RESULTS: The treatment course was documented by means of study casts and lateral cephalograms. Assessment of the diagnostic records yielded the following findings: In the early treatment group the maxillary molars were distalized by the pendulum appliance by a mean distance of 4.0 +/- 1.46 mm, resulting in distal tipping by 6.1 +/- 2.18 degrees. The incisors were moved reciprocally by 1.08 +/- 1.06 mm to anterior and protruded by 7.65 +/- 4.84 degrees. In the comparison group molar distalization and molar tipping were less pronounced (2.86 +/- 1.54 mm/4.25 +/- 3.78 degrees ), while mesial movement of the incisors was comparably high at 1.62 +/- 0.99 mm. At only 3.8 +/- 2.9 degrees, incisor protrusion was significantly less pronounced than in the early treatment group (p = 0.045). The proportion of molar distalization in the total movement was higher in patients in the early mixed dentition: 79.83 +/- 15.38% vs 60.71 +/- 26.64%. During the early therapy with the lingual arch appliance in the lower arch, the molars were uprighted to the distal by 2.4 +/- 0.97 degrees and the incisors were tipped to labial by 5.0 +/- 1.83 degrees. In the adolescent control group, molar uprighting was less pronounced and the degree of incisor protrusion was significantly lower (2.75 +/- 1.11 degrees, p = 0.004). CONCLUSION: With the appropriate indication, the combined therapy with the two compliance-independent appliances described can be recommended for gaining sagittal arch length in the early mixed dentition.     

Dietary factors in the prevention of dental caries: a systematic review

The aim of this study was, systematically, to evaluate the effect of dietary changes in the prevention of dental caries. A search and analysis strategy was followed, as suggested by the Swedish Council on Technology Assessment in Health Care (SBU). The search strategy for articles published in 1966-2003 was performed using electronic databases and reference lists of articles and selected textbooks. Out of 714 articles originally identified, 18 met the inclusion criteria for a randomized or controlled clinical trial--at least 2 years' follow-up and caries increment as a primary endpoint. This included the total or partial substitution of sucrose with sugar substitutes or the addition of protective foods to chewing gum. No study was found evaluating the effect of information designed to reduce sugar intake/frequency as a single preventive measure. It is suggested that the evidence for the use of sorbitol or xylitol in chewing gum, or for the use of invert sugar, is inconclusive. No caries-preventive effect was found from adding calcium phosphate or dicalcium phosphate dihydrate to chewing gums. The review dearly demonstrates the need for well-designed randomized clinical studies with adequate control groups and high compliance.