By David L. Turpin, Editor-in-Chief
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Editor’s Choice September – 2010

Expectations, acceptance and preferences regarding microimplant treatment in orthodontic patients

A randomized controlled trial

Martin Baxmann, Fraser McDonald, Christoph Bourauel, Andreas Jäger

When you plan treatment for a patient with maximum anchorage requirements and decide to use microimplants to accomplish your treatment objectives, how do you explain the procedure for placing implants to the patient? Most patients I know think the placement of such devices will be painful. Even though a variety of dental procedures may be common to the orthodontic patient, the comparative pain associated has not been investigated to establish to what extent they will be tolerated. The aim of this study was to compare the pain associated with microimplant placement supported by the dental procedures routinely accompanying the insertion, such as soft tissue preparation by punch insertion and tooth extraction

Twenty-eight consecutive orthodontic patients fulfilling the inclusion criteria were recruited for this study. The inclusion criteria required that they were in the permanent dentition, under the age of 18 years, had an orthodontic treatment need and included a treatment plan which involved maxillary or maxillary and mandibular premolar extractions, en-masse retraction for the reduction of an excessive overjet and maximum anchorage requirements. The patients were randomized and stratified by gender into two groups. Group A comprised of seven males and seven females and group B also seven males and seven females. In group A at least one extraction was performed before placement of the microimplant. In group B all extractions were performed following the insertion of the microimplant. Two placement techniques were used for each patient in a split-mouth-design. On the left side the Tomas-punch was used for gingival tissue removal in the insertion area. On the right hand side the microimplant was transgingivally inserted.

Take home points:

• All patients described the extractions as more uncomfortable than the microimplant placement.
• The soft tissue punch led to significantly higher discomfort levels compared to the transgingival placement. The feeling that produced the discomfort was described as pain in the punch group but pressure rather than pain in the transgingival insertion group.
• No differences could be observed when comparing the pain and discomfort values of patients under the median age of 14.85 with the older patients.

Anatomical variability in the alveolar sites of skeletal anchorage

Fernando Lima, Martinelli, Ronir R Luiz, Marcelo Faria and

Lincoln I Nojima

Rio de Janeiro, Brazil

When planning treatment that may call for the placement of miniscrew implants for anchorage, 3 specific dimensions have been given particular attention in the literature: the cortical thickness, buccolingual space and interradicular distance. These factors are important for selecting the miniscrew-type as well as the angle and depth of insertion. Although computed tomography (CT) is a method that allows for detection of a three-dimensional arrangement of the anatomical elements, how reliable is CT for this purpose and is its use always necessary? The objective of this study was to evaluate the pattern of variability of the alveolar dimensions in the insertion sites and comprehend the reliability of the values measured on CT sections.

The sample comprised 22 adults presenting complete permanent dentition and periodontal health. A high resolution computed tomography imaging (Somaton Spirit, Siemens, Munich, Germany) was obtained for analysis of the dental arch where skeletal anchorage was planned. The thickness and the interval of axial sections were 1.0 mm and 1.0 mm, respectively, at the posterior region of arch. The results of this study confirm the findings of other recent studies. In the maxillary and mandibular cervical zones, the interradicular distances in the molars were significantly greater than those found in the incisor sites. The apical distance was statistically wider than the cervical areas of the anterior teeth. The maxillary buccal cortical bone was less thick than the lingual areas and the mandibular buccal cortical bone in the corresponding apical zones. More simply put, look to the interradicular space between molars for the most successful skeletal anchorage. Overall, skeletal anchorage reached stability by the use of miniscrews that were 1.5 to 2.3 mm in diameter.

Long-term development of malocclusion traits in orthodontically treated and untreated subjects

Teitur Jonsson, Karl O Karlsson, Bjorn Ragnarsson and Thordur E

Magnusson

As orthodontists we are familiar with the dramatic changes routinely observed as a result of our treatment of most malocclusions. But over the period of a lifetime, do we ever consider the permanency of such changes or do they eventually fade away in the following decades of slow physiologic change? In this study the authors compared changes in treated and untreated subjects in an attempt to describe the long-term net effect of the orthodontic intervention. However, as subjects could logically not be randomly assigned to the respective groups, the orthodontic problems were more prevalent in the treated group initially, necessitating caution in this comparison.

Nevertheless, this is an interesting paper that describes 4 features of the occlusion in a cohort of 308 people who were studied as adolescents and then again about 25 years later.  As such, it provides uncommon data about how people's occlusion changes with age. The original study was conducted on 1,641 children in the early 1970s. The follow-up study collected data on 832 people who had been participants in the first study, but, after fitting some selection criteria, the final usable longitudinal study contained 308 people. Conventionally, these 308 people would be compared to the 1,641 original people (or at least the 832 people that are matched at both time periods) in order to confirm that the selected sample is representative.

The following traits were recorded: Overjet 6-9 mm, and 9 mm and over, overbite 5-7 mm and 7 mm and over, crossbite on 1 molar or more, mesial and distal first molar occlusion deviating half cusp-width or more from normal. All malocclusion traits have a higher prevalence in the treated group of 58 subjects at T1; significantly for overjet, distal molar occlusion and molar crossbite. At T2 the untreated subjects have a lower prevalence of crossbite than the non-extraction treated group. Results describe the development of treated groups, using development in the untreated group as a baseline. The statistical analysis showed that both in extraction and non-extraction treatment categories the development of overjet was significantly more favorable than in untreated subjects. Non-extraction treatment affects distal molar relation favorably, and molar crossbite develops adversely in the non-extraction treated group.

If I correctly understand the authors' perspective, they are suggesting that orthodontic treatment is inconsequential when compared to the net changes occurring over about 3 decades of normative aging. This perspective is only supportable when ignoring the magnitudes of the changes (as in this paper). This is not a criticism of the manuscript, but some disagree with the authors' choice of how the data can be interpreted. It is worth noting that the quality of the orthodontic service may play a role in the long-term development. The treatment approach in this study ranged from removable appliances to conventional fixed appliances and may have been compromised at times, but it can be described as a service carried out exclusively by authorized specialists, educated in US and the Scandinavian countries. The non-extraction treatment is in the majority of cases carried out with removable or functional appliances, while extraction treatment is associated with fixed appliances. Overall, within this pattern of long-term observation, developmental changes seem to be generally similar in treated and untreated subjects. It could be said that over time individual variation may to some extent conceal the effects of a brief orthodontic intervention.