The effect of extraction of third molars on late lower incisor crowding: a randomized controlled trial

Short-term postorthodontic changes in the absence of retention

OBJECTIVE

To evaluate short-term postorthodontic tooth movement without retention.

MATERIALS AND METHODS

Thirty consenting patients participated in the study. At the end of active treatment (T(1)), final archwires were removed while leaving the fixed appliances on, and alginate impressions were taken. Four weeks later (T(2)) a second set of impressions was taken. A clinical examination performed at T(2) determined if the fixed appliances could be removed or if additional treatment was required. Based on the examination, patients were divided into two groups. Patients in group I (n = 13) had their fixed appliances removed, while those in group II (n = 17) required additional treatment. The American Board of Orthodontics' Objective Grading System scores and the following six variables were measured on plaster casts at T(1) and T(2): maxillary and mandibular crowding or spacing, overbite, overjet, and mandibular intercanine and intermolar widths. Data were analyzed to detect potential changes from T(1) to T(2) and to evaluate differences between the groups.

RESULTS

Mandibular crowding, overjet, and interproximal contacts worsened for the entire sample, while marginal ridges, occlusal contacts, and total American Board of Orthodontics scores improved. No statistically significant changes were found within group I from T(1) to T(2). Mandibular crowding, overbite, overjet, alignment/rotations, and interproximal contacts worsened within group II from T(1) to T(2), while marginal ridges and occlusal contacts improved. Significant differences were noted between the groups in terms of alignment/rotations, interproximal contacts, and mandibular intercanine width.

CONCLUSION

Short-term postorthodontic tooth movement without retainers demonstrated improvement in specific characteristics of the occlusion but negatively affected alignment and interproximal contacts in the sample.

Opinions of American and Swedish orthodontists about the role of erupting third molars as a cause of dental crowding

OBJECTIVE

To compare the opinions of Swedish orthodontists and American orthodontists regarding the association between third molar eruption and dental crowding.

MATERIALS AND METHODS

A survey was distributed to Swedish orthodontists (n = 230) asking their views on the force exerted by erupting third molars, its relationship to crowding, and their recommendations for prophylactic removal. Results were compared with those from a similar study conducted in the United States. Chi square analysis was used to determine differences in responses to questions between Swedish and American orthodontists. P < or = .05 was considered significant.

RESULTS

Both Swedish and American orthodontists believed that lower third molars were more likely than upper third molars to cause force (65% and 58% for Swedish and American orthodontists, respectively) and crowding (42% and 40%, respectively). No statistically significant differences were seen between the answers of American and Swedish orthodontists regarding the role of upper and lower third molars in causing crowding. Although only 18% of Swedish orthodontists "generally" or "sometimes" recommended prophylactic removal of mandibular third molars, 36% of American orthodontists "generally" or "sometimes" recommended removal (P < .0001).

CONCLUSIONS

Most orthodontists in the United States and Sweden do believe that erupting lower third molars exert an anterior force; however, they also believe that these teeth "rarely" or "never" cause crowding of the dentition. The reason that more American orthodontists recommend prophylactic removal of mandibular third molars remains unexplained.

Ortodontia baseada em evidência científica: incorporando ciência na prática clínica

O objetivo deste artigo é despertar o ortodontista e conscientizá-lo sobre a importância da tomada de decisão baseada em evidência científica no cuidado aos pacientes. Serão descritos os passos essenciais para a prática da Odontologia baseada em evidência (OBE), assim como os princípios da ciência e da pesquisa. Existem caminhos adequados para a busca da informação de qualidade, sendo esses a única garantia de encontrar artigos válidos. Na seleção de artigos científicos, o primeiro passo é definir o seu desenho, pois para cada dúvida clínica há um delineamento adequado capaz de respondê-la. Dessa maneira, questões sobre tratamento, etiologia, diagnóstico, prognóstico ou prevenção só podem ser respondidas por um artigo que tenha sido delineado para tal. O conhecimento da alocação randomizada, do mascaramento e do grupo-controle é fundamental para que possamos realizar uma leitura crítica dos artigos científicos, reconhecendo os que merecem credibilidade. Em meio a tantas publicações, precisamos definir, com segurança, o que deve ser incorporado ao nosso conhecimento e o que deve ser incorporado à prática clínica, mudando a nossa conduta. Desse modo, poderemos oferecer aos nossos pacientes opções terapêuticas mais consistentes e previsíveis.

Extraction versus nonextraction management of third molars

Surgical removal of impacted third molars is the most commonly performed procedure by oral and maxillofacial surgeons. The removal of diseased or symptomatic third molars has not been an issue of controversy. The risk of surgery and associated complications are justified and uniformly accepted by most surgeons when the teeth are associated with chronic or acute pathologic processes, including caries, nonrestorable teeth, fractured roots, resorption, associated pathologic conditions (cysts, tumors), periapical abscesses, odontogenic infections, osteomyelitis, removal before reconstructive or ablative surgery, and radiation therapy.

The prophylactic extraction of third molars: a public health hazard

Ten million third molars (wisdom teeth) are extracted from approximately 5 million people in the United States each year at an annual cost of over $3 billion. In addition, more than 11 million patient days of "standard discomfort or disability"--pain, swelling, bruising, and malaise--result postoperatively, and more than 11000 people suffer permanent paresthesia--numbness of the lip, tongue, and cheek--as a consequence of nerve injury during the surgery. At least two thirds of these extractions, associated costs, and injuries are unnecessary, constituting a silent epidemic of iatrogenic injury that afflicts tens of thousands of people with lifelong discomfort and disability. Avoidance of prophylactic extraction of third molars can prevent this public health hazard.

Orthodontists' and surgeons' opinions on the role of third molars as a cause of dental crowding

INTRODUCTION

Despite a substantial body of literature refuting an association between third molar eruption and crowding of the anterior dentition, the issue continues to be controversial.

METHODS

A survey was developed to evaluate and compare the current opinions of orthodontists (n = 393) and oral and maxillofacial surgeons (n = 458) regarding the link between third molars and the development of anterior crowding.

RESULTS

A smaller percentage of orthodontists than surgeons believed that maxillary (P <.0001) and mandibular (P <.0001) third molars produce anterior forces during eruption. Similarly, orthodontists were less likely to think that maxillary (P <.0001) and mandibular (P <.0001) third molars cause anterior crowding and were therefore less likely to recommend prophylactic removal of maxillary (P <.0001) and mandibular (P <.0001) third molars to prevent crowding. Surgeons were more likely to "generally" or "sometimes" (56.9%) recommend prophylactic removal of mandibular third molars to prevent crowding, whereas orthodontists more often said that they "rarely" or "never" (64.4%) recommend it. Differences in orthodontists' and oral and maxillofacial surgeons' beliefs about the association between third molar eruption and the development of crowding were significantly related to graduation year. More recently graduated orthodontists were less likely to recommend prophylactic removal of third molars to prevent crowding, and surgeons were more likely to recommend removal if they graduated in the 1970s or 1980s.

CONCLUSIONS

Significant disagreement exists among practitioners, including both orthodontists and oral and maxillofacial surgeons, regarding the fundamental issues underlying the role of third molars in dental crowding.

Panoramic radiographic predictors of mandibular third molar eruption

OBJECTIVE

Third molar (M3) eruption can be problematic. According to some orthodontic surgeons, the teeth are capable of aggravating the average crowding level in the dental arch. The question is whether it might be possible to give a prognosis for ultimate M3 position in the arch and make an early decision to extract or retain them. The purpose of the study was to determine which measurements made on panoramic tomograms might facilitate prognosis for M3 position in the dental arch over the years.

STUDY DESIGN

The investigation involved 64 patients who had been enrolled to the study group 10 years earlier, ie, in 1993, when an analysis had been carried out regarding M3 effect on dental arch crowding. At that time panoramic tomograms had been taken, and dental casts made. The procedures were repeated in 2003. The following measurements were taken at baseline (1993) and at the end of the study (2003): (1)/the retromolar space to lower third molar crown width, (2) third molar angulation to the base of the mandible, and (3) third molar to second molar inclination.

RESULTS

At some defined values of the Ganss ratio, and M3 inclination to mandibular base and second molar, it is possible to predict potential lower third molar alignment in the dental arch using a panoramic radiograph.

Retention procedures for stabilising tooth position after treatment with orthodontic braces

BACKGROUND

Retention is the phase of orthodontic treatment that attempts to keep teeth in the corrected positions after treatment with orthodontic (dental) braces. Without a phase of retention there is a tendency for the teeth to return to their initial position (relapse). To prevent relapse almost every patient who has orthodontic treatment will require some type of retention.

OBJECTIVES

To evaluate the effectiveness of different retention strategies used to stabilise tooth position after orthodontic braces.

SEARCH STRATEGY

The Cochrane Oral Health Group's (OHG) Trials Register, CENTRAL, MEDLINE and EMBASE were searched. Handsearching of orthodontic journals was undertaken in keeping with the Cochrane OHG search programme. No language restrictions were applied. Authors of randomised controlled trials (RCTs) were identified and contacted to identify unpublished trials. Most recent search: May 2005.

SELECTION CRITERIA

RCTs on children and adults, who have had retainers fitted or adjunctive procedures undertaken, following orthodontic treatment with braces to prevent relapse. The outcomes were: how well the teeth were stabilised, survival of retainers, adverse effects on oral health and quality of life.

DATA COLLECTION AND ANALYSIS

Screening of eligible studies, assessment of the methodological quality of the trials and data extraction were conducted in duplicate and independently by two review authors. As no two studies compared the same retention strategies (interventions) it was not possible to combine the results of any studies.

MAIN RESULTS

Five trials satisfied the inclusion criteria. These trials all compared different interventions: circumferential supracrestal fiberotomy (CSF) combined with full-time removable retainer versus a full-time removable retainer alone; CSF combined with a nights-only removable retainer versus a nights-only removable retainer alone; removable Hawley retainer versus a clear overlay retainer; multistrand wire retainer versus a ribbon-reinforced resin bonded retainer; and three types of fixed retainers versus a removable retainer. There was weak unreliable evidence, based on data from one trial, that there was a statistically significant increase in stability in both the mandibular (lower) (P < 0.001) and maxillary (upper) anterior segments (P < 0.001) when the CSF was used, compared with when it was not used. There was also weak, unreliable evidence that teeth settle quicker with a Hawley retainer than with a clear overlay retainer after 3 months. The quality of the trial reports was generally poor.

AUTHORS' CONCLUSIONS

There are insufficient research data on which to base our clinical practice on retention at present. There is an urgent need for high quality randomised controlled trials in this crucial area of orthodontic practice.

Interventions for treating asymptomatic impacted wisdom teeth in adolescents and adults

BACKGROUND

The prophylactic removal of asymptomatic impacted wisdom teeth is defined as the (surgical) removal of wisdom teeth in the absence of local disease. Impacted wisdom teeth have been associated with pathological changes, such as inflammation of the gums around the tooth, root resorption, gums- and alveolar bone disease, damage of the adjacent teeth, the development of cysts and tumours. Several other reasons to justify prophylactic removal have also been given. Wisdom teeth do not always fulfil a functional role in the mouth. When surgical removal is carried out in older patients the risk of more postoperative complications, pain and discomfort increases. Nevertheless, in most developed countries the prophylactic removal of trouble-free wisdom teeth, either impacted or fully erupted, has long been considered as 'appropriate care'. Prudent decision-making, with adherence to specified indicators for removal, may reduce the number of surgical procedures by 60% or more. It has been suggested that watchful monitoring of asymptomatic wisdom teeth may be an appropriate strategy.

OBJECTIVES

To evaluate the effect of prophylactic removal of asymptomatic impacted wisdom teeth in adolescents and adults compared with the retention of these wisdom teeth.

SEARCH STRATEGY

The following electronic databases were searched:The Cochrane Oral Health Group Trials Register (4 August 2004), the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (1966 to 4 August 2004), PubMed (1966 to 4 August 2004), EMBASE (1974 to 4 August 2004). There was no restriction on language. Key journals were handsearched. An attempt was made to identify ongoing and unpublished trials.

SELECTION CRITERIA

All randomised or controlled clinical trials (RCTs/CCTs) comparing the effect of prophylactic removal of asymptomatic impacted wisdom teeth with no-treatment (retention).

DATA COLLECTION AND ANALYSIS

Assessment of relevance, validity and data extraction were conducted in duplicate and independently by three reviewers. Where uncertainty existed, authors were contacted for additional information about randomisation and withdrawals. A quality assessment of the trials was carried out.

MAIN RESULTS

Only three trials were identified that satisfied the review selection criteria. Two were completed RCTs and both assessed the influence of prophylactic removal on late incisor crowding in adolescents. One ongoing RCT was identified, but the researchers were unable to provide any data. They intend to publish in the near future and information received will be included in updates. Although both completed trials met the inclusion criteria of the review, regarding participants characteristics, interventions and outcomes assessed, different outcomes measures were assessed which prevented pooling of data.

AUTHORS' CONCLUSIONS

No evidence was found to support or refute routine prophylactic removal of asymptomatic impacted wisdom teeth in adults. There is some reliable evidence that suggests that the prophylactic removal of asymptomatic impacted wisdom teeth in adolescents neither reduces nor prevents late incisor crowding.

The influence of providing a clinical practice guideline on dental students' decision making

The aim of this study was to assess the effect of the provision of a clinical practice guideline (CPG) on dental students' decisions to remove asymptomatic, impacted lower third molars. All dental students, who in 2001 were in the 3rd, 4th or 5th (final) year of their study at the Nijmegen College of Dental Sciences, were invited to participate. A pre-test-post-test control group design was used. Given 36 patient cases, all dental students were asked to assess the need for removal of asymptomatic, impacted lower third molars. All pre-test respondents were randomly allocated to the control or intervention group. After the provision of a CPG to the intervention group, both groups were asked to assess the same cases again. Frequencies of decisions to remove the third molars were calculated. Chi-square tests and anova were used to test the influence of study year and gender on the drop-out rate and on the effect of the provision of a CPG on students' treatment decisions. The decrease in indications to remove third molars by the intervention group was statistically significant (P < 0.05). In the control group, no significant decrease was observed. It was concluded that the provision of a CPG significantly influences dental students' decision making about treatment in a third-molar decision task. Students who used the CPG showed more guideline-conformed decision making.

Retention procedures for stabilising tooth position after treatment with orthodontic braces

BACKGROUND

Retention is the phase of orthodontic treatment that attempts to keep teeth in the corrected positions after orthodontic (dental) braces. Without a phase of retention there is a tendency for the teeth to return to their initial position (relapse). To prevent relapse almost every patient who has orthodontic treatment will require some type of retention.

OBJECTIVES

To evaluate the effectiveness of different retention strategies used to stabilise tooth position after orthodontic braces.

SEARCH STRATEGY

The Cochrane Oral Health Group's Trials Register, CENTRAL, MEDLINE and EMBASE were searched. Several journals were handsearched. No language restrictions were applied. Authors of randomised controlled trials (RCTs) were identified and contacted to identify unpublished trials. Most recent search: December 2002.

SELECTION CRITERIA

RCTs on children and adults, who have had retainers fitted or adjunctive procedures undertaken, following orthodontic treatment with braces to prevent relapse. The outcomes are: how well the teeth are stabilised, survival of retainers, adverse effects on oral health and quality of life.

DATA COLLECTION AND ANALYSIS

Screening of eligible studies, assessment of the methodological quality of the trials and data extraction were conducted in duplicate and independently by two reviewers. As no two studies compared the same retention strategies (interventions) it was not possible to combine the results of any studies.

MAIN RESULTS

Four trials satisfied the inclusion criteria. These trials all compared different interventions: circumferential supracrestal fiberotomy (CSF) combined with full-time removable retainer versus a full-time removable retainer alone; circumferential supracrestal fiberotomy (CSF) combined with a nights-only removable retainer versus a nights-only removable retainer alone; removable Hawley retainer versus a clear overlay retainer; and three types of fixed retainers versus a removable retainer. There was weak unreliable evidence, based on data from one trial, that there was a statistically significant increase in stability in both the mandibular (p < 0.001) and maxillary anterior segments (p < 0.001) when the CSF was used, compared with when it was not used. There was also weak, unreliable evidence that teeth settle quicker with a Hawley retainer than with a clear overlay retainer after 3 months. The quality of the trial reports was generally poor.

REVIEWER'S CONCLUSIONS

There are insufficient research data on which to base our clinical practice on retention at present. There is an urgent need for high quality randomised controlled trials in this crucial area of orthodontic practice.

Effect of selected literature on dentists' decisions to remove asymptomatic, impacted lower third molars

The aim of this study was to assess the effect of studying selected literature on dentists' decisions to remove asymptomatic, impacted lower third molars. A pre-test-post-test control group design was used. Given 36 patient cases, two groups of 16 general dental practitioners each were asked to assess the need for removal of asymptomatic impacted lower third molars. The cases were classified by three parameters: 'position of the third molar', 'impaction type', and 'patient age'. After studying selected literature on this subject by the intervention group, both groups were asked to assess the same cases again. Frequencies of decisions to remove the third molars were calculated. For each participant, tables were composed by crosstabulating the indication to remove a third molar with each of the three parameters. T-tests were used to test the significance of the difference between pre-test and post-test decisions. The overall number of indications to remove asymptomatic, impacted lower third molars decreased by 37% in the intervention group. In the control group, the difference between pre- and post-test was not statistically significant. It was concluded that the provision of selected literature significantly influences treatment decision making by dentists in a third molar decision task.

Influence of orthodontic treatment on development of third molars

We aimed to find out whether extraction of lower premolars and subsequent closure of the space by a fixed appliance influenced the chances of mandibular third molars erupting. We compared angular and linear measurements of lower third molars on dental panoramic tomograms in 30 orthodontic patients with similar measurements from 30 patients with impacted third molars in intact arches. We found that the mesial angulation of lower third molars was reduced from 50 degrees to 43 degrees by orthodontic treatment (P< 0.001). Distance to the occlusal plane was reduced from 12 mm to 10 mm (P< 0.001). The space available increased from 4 mm to 11 mm (P< 0.001). We conclude that extraction of lower premolars and orthodontic treatment to achieve complete closure of the space allowed the positions of many impacted lower third molars to improve significantly.