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SummaryFine orthodontic treatment results are fine. Fine stable results are finer. But when is stability achieved? Many studies show that the decline from optimal alignment and occlusion is most rapid immediately after appliance removal and slows down after some three to five years. For stabilization, we need some form of retention. Many retention regiments have been proposed sometimes with almost missionary fervour. The following commentary is a rather personal, but yet objective evaluation to highlight the quality evidence that the article by Edman, Petrén, Bondemark, and Lilja-Karlander presents which helps us clinicians to make informed decisions about orthodontic retention technique. It also underscores why the article is a masterpiece.

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CLINICAL QUESTION: How effective is a therapy which relies solely on removable orthodontic appliances? PATIENTS: A group of 276 consecutive patients, whose mean age was 9.50 years, diagnosed with various types of malocclusion, whose records were complete, and who were treated solely with removable appliances. METHODS: Measurement of the PAR Index of the pre- and post-treatment study casts, standard statistical analyses, calculation of the correlation coefficients, and method error. RESULTS: The mean pre-treatment PAR score was 19.5, the mean post-treatment PAR score 5.9. In the PAR nomogram, 79% of the patients were classified as "improved", and 16% as "greatly improved". In contrast, 5% had to be classified as "worse/no different". The overall situation improved by a mean of 14 PAR points, corresponding to a mean improvement of 68%. CONCLUSION: Using the PAR Index as a standard, removable appliances can be used successfully to correct malocclusions, providing the indication is correct and the clinician's expertise in this field of the speciality is very high.

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OBJECTIVE: Evaluation of the periodontal health of patients during treatment with the Invisalign system or fixed lingual appliances. STUDY DESIGN: The study was designed as a concomitant trial of two groups of consecutive patients. The lingual patients were evaluated between February and May 2005. PATIENTS AND METHODS: Thirty patients each with aligners or fixed lingual appliances were examined at three consecutive control visits for their periodontal status. All the Invisalign patients and some of those wearing lingual appliances were patients from the Department of Orthodontics and Dentofacial Orthopedics of the Charité Berlin. The rest were recruited from the practices of two licensed orthodontists. The patients' periodontal health was evaluated in reference to a modified Gingiva, modified Plaque and modified Papillary Bleeding Index; we also measured the sulcus probing depth. All indices were documented buccally in the 1st and 3rd quadrants, and lingually in the 2nd and 4th quadrants from central incisor to first molar. The sulcus probing depth was measured mesially, distally, buccally and lingually in each quadrant's first molar and first premolar. Each control visit was concluded with detailed, individualized instructions in oral hygiene. RESULTS: Overall, the Invisalign patients demonstrated significantly better modified indices. However, the sulcus probing depths were very similar in both treatment groups. CONCLUSION: Although all the teeth and parts of the keratinized gingiva are covered nearly all day during Invisalign treatment, the periodontal risk is lower than that associated with fixed lingual appliances. This may be due to the fact that aligners are removable, permitting unimpeded oral hygiene. In contrast, the lingual tooth surfaces are very difficult to clean when fitted with a fixed appliance.

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AIM: Evaluation of tongue movements during swallowing with a computer-aided, M-mode ultrasonography system in combination with a cushioning device. SUBJECTS AND METHOD: Motion pattern and activity duration of the tongue dorsum during swallowing were investigated in 55 volunteers. RESULTS: The duration, amplitude and pattern of tongue movements during swallowing differed interindividually, whereas they were reproduced well intra-individually. We thus observed three characteristic variations in phases I and IIIb and two in phases IIb and IIIa. The movement pattern in phase IIa and in the rest phase was uniform. CONCLUSIONS: M-mode ultrasonography provides valid information on tongue movements without any side-effects and is thus a useful tool in the diagnosis and research of tongue functions in orthodontics and dentistry.

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OBJECTIVE: We investigated whether there is a correlation between the buccolingual crown diameter and cusp tip distance and if that can be considered a factor influencing the formation of a transversal malocclusion. MATERIALS AND METHODS: The buccolingual crown diameters and cusp tip distances of all premolars and first molars of 102 normal dentitions and 123 dentitions with a transverse malocclusion were measured and examined for significant differences. We also investigated whether there were differences in size between the genders and between left and right sides. RESULTS: General differences in buccolingual crown diameters ranged from 0.3 mm to 0.6 mm, and in cusp tip distance from 0.4 mm to 0.7 mm. Buccolingual crown width was generally greater in boys than girls, whereas we observed no statistically significant difference in cusp tip distances. Comparison of left and right sides revealed no significant difference. We were able to statistically prove the correlation between buccolingual tooth diameter and cusp tip distance. CONCLUSIONS: The results suggest that larger teeth with a greater cusp tip distance offer a more favorable prerequisite for the appearance of regular transversal occlusal relations than those with a smaller distance. The buccolingual crown width and its corresponding cusp tip distance seem important for initial contact with the antagonists, and may be regarded as a factor that determines whether or not a crossbite develops.

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BACKGROUND: Ectodermal dysplasia is an inherited disease causing malformations of all tissues originating from the ectoderm. The significance of this disease lies in severe hypodontia, and an accompanying hypoplasia of the alveolar process. The clinical situation is aggravated by a significant xerostomia. It was the aim of this study to document the distribution of hypodontia and tooth malformation. Furthermore, we aimed to elucidate the clinical impact of these findings. PATIENTS AND METHODS: Records of 30 patients (19 males, 11 females) suffering from ectodermal dysplasia were included. Their age ranged between 7 and 23 years. All patients had been examined clinically and radiographically. In every patient, a record was made of which teeth were missing or malformed, and which deciduous teeth persisted. Additionally, the entire treatment procedure was assessed. RESULTS: The third molars were missing in all of the patients. The number of aplastic permanent teeth ranged from 2 to 26. The maxillary lateral incisors were most frequently absent, followed by the mandibular central incisors. The most stable teeth were the central incisors of the upper jaw, and the canines and first molars in both jaws. However, the maxillary central incisors and canines were the teeth most affected by malformation. Deciduous canines and second molars were the most often persisting teeth due to agenesis of the maxillary lateral permanent incisors and mandibular second premolars. In two-thirds of the patients, missing teeth were replaced by removable dentures. Half of the patients received orthodontic treatment. CONCLUSIONS: Hypodontia and malformation are almost regular dental characteristics in patients suffering from ectodermal dysplasia. The distribution of absent teeth deviates remarkably from the general population. Treatment requires an interdisciplinary approach including orthodontics, prosthodontics and oral surgery.

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OBJECTIVE: Evaluation of the periodontal health in patients during treatment with either fixed orthodontic appliances or the Invisalign system. STUDY DESIGN: The study was designed as a concomitant trial. The evaluation of the patients started in February 2002 and was completed in August 2003. PATIENTS AND METHODS: Thirty consecutive patients each with fixed orthodontic appliances and with aligners were examined at three consecutive control visits for their periodontal condition. All individuals were part of the clientele of the Department of Orthodontics and Dentofacial Orthopedics of the Charité Berlin. The parameters evaluated were the modified Gingival Index, modified Plaque Index, modified Papillary Bleeding Index, and sulcus probing depth. The first three indices were recorded alternatively buccally and lingually in all permanent teeth from central incisor to first molar: buccally in the maxillary right and the mandibular left quadrants, lingually in the maxillary left and mandibular right quadrants. The sulcus depth was measured in four areas: mesially and distally, lingually and buccally in the 1st molar and the 1st premolar of each quadrant. Each control visit was concluded with a detailed, individualized oral hygiene instruction. RESULTS: The modified Plaque Index was significantly lower in the Invisalign group overall. On the other hand, the periodontal condition of the two samples was nearly identical. CONCLUSION: Periodontal health is not jeopardized, even though the Invisalign system aligners cover all the teeth and the keratinized gingiva in part. This could be attributed to the fact that aligners are removable and thus allow unimpeded oral hygiene.

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AIM: This study examined how well patients accepted and to what extent they were impaired by Invisalign treatment. PATIENTS AND METHODS: Fifty-four consecutive patients received a questionnaire with 12 questions after 3 to 6 months of Invisalign treatment. They were given a choice of three responses for each question. Apart from personal data, the questionnaire covered the following parameters: adaptation time, occurrence and duration of pain, possible speech impairment, lingual and mucosal irritations, temporomandibular joint (TMJ) problems and subjective assessment of the success of therapy thus far and the quality of information initially provided. RESULTS: 78% of those interviewed were females. The highest percentage of patients (44%) were between 20 and 30 years of age. 83% got used to their aligners within one week. 35% had no pain and 54% mild pain while wearing them. This pain usually lasted for 2 to 3 days following insertion of a new aligner. 46% of the patients experienced no speech impairment. 93% felt so secure with their aligners that they felt not at all inhibited about speaking. The majority noticed no narrowing of the lingual space (76%) or irritation of the lingual or buccal mucosa (70%). However, 6% had strong irritations. 44% of the patients had difficulty chewing, mainly because the teeth were sensitive to pressure or had food particles caught between them due to temporary gaps. TMJ problems in terms of clicking were reported by 8% of the patients, although the clicking had existed before therapy initiation. None of the patients had TMJ pain. At the time of the interview, 89% of the patients were satisfied with the progress of therapy. All patients considered themselves well or very well informed about the treatment. CONCLUSIONS: Invisalign therapy seems particularly attractive to a clientele comparable to that for the lingual technique. Patients show high acceptance, since they become accustomed to the aligners very quickly and do not suffer much impairment. If indicated, Invisalign therapy should thus be considered an alternative to the lingual technique for esthetically-demanding patients. This applies especially to patients who cannot be treated by the lingual technique because of the inevitable speech impairment.

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AIM: The aim of the present prospective study was to produce a profile of those patients who are interested in treatment with the Invisalign system. PATIENTS AND METHODS: Personal data and clinical findings of 89 patients attending the Invisalign consulting hours offered by the Department of Orthodontics and Dentofacial Orthopedics, Charité Medical School were recorded. Personal data included gender, age, profession, motivation for treatment, accepted treatment duration, and initial source of information; clinical findings included anomalies of tooth position and jaw relationship as well as oral hygiene. RESULTS: Statistical analysis of the data revealed a characteristic profile: Mainly women between 20 and 29 years of age were interested in Invisalign treatment, chiefly for esthetic reasons, accepting a treatment time of 1.5 to 2.5 years. The majority of patients rejected treatment with visible appliances. 41% had been initially informed of this new treatment system by their dentist or an orthodontist, and the same percentage through different media. The standard of oral hygiene was only moderate or low in 54% of all subjects. Frontal crowding was diagnosed in 87%, and a Class II malocclusion in 49%. CONCLUSIONS: The demand for orthodontic treatment mainly among women is substantial, but many of these potential patients baulk at the esthetic impairment induced by a fixed labial appliance or the speech disturbances induced by a lingual appliance. In order to increase the acceptance of new treatment methods, the high demands placed by those concerned on esthetic and phonetic aspects should therefore be respected. With respect to oral hygiene, many patients are still in urgent need of professional instruction.

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In order to investigate the difference in tongue movement between visceral (infantile) and somatic (mature) swallowing patterns, 12 visceral (seven females, five males) and 14 somatic (eight females, six males) swallowers were examined with the B+M-mode ultrasound technique. Movements of the tongue tip and submental musculature during swallowing were recorded on video cassette and evaluated with a personal computer. The results demonstrated that the tongue dorsal surface, which was thought to be ideal for observing tongue function, was not suitable for differentiating between visceral and somatic swallowing patterns. Conversely, the movements of the genioglossus muscle were found to be identical within groups but significantly different (P < 0.01) from each other between the two swallowing patterns. Therefore, the genioglossus muscle can serve as a reliable means for differentiating between visceral and somatic swallowers.

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