Frequency of tooth extraction in orthodontic treatment

Integrating machine learning for treatment decisions in anterior open bite orthodontic cases: A retrospective study

INTRODUCTION

This article explores the integration of machine learning (ML) algorithms to aid in treatment planning and extraction decisions for anterior open bite cases, leveraging demographic, clinical, and radiographic data to predict treatment outcomes and informed decision-making.

MATERIALS AND METHODS

A retrospective study was conducted using patient data from the University of Illinois Chicago Department of Orthodontics. Data included demographic, clinical, and radiographic information from 115 anterior open bite patients who successfully completed their treatment. ML algorithms, including random forest, support vector machine, k-nearest neighbor, and convolutional neural networks (CNN), were trained on a subset of the data to predict treatment outcomes.

RESULTS

Significant differences were observed in the percentages of males and females between the extraction and nonextraction groups and cephalometric variables between the two groups, which include maxillary depth, maxillary height, SN-palatal plane, facial angle, facial axis-Ricketts, FMA, total facial height, lower facial height, SNA, SNB, and SN-MP e ML algorithms examined consisted of CNN2, CNN1, and Random Forest, which demonstrated the highest accuracy rates (∼83%), while k-Nearest Neighbor had the lowest (∼73%). Key features influencing accuracy included crowding, SN-palatal plane, SNA, FMA, molar relation, and facial height measurements.

CONCLUSIONS

The study's evaluation of AI algorithms showed that CNN2, CNN1, and random forest had an accuracy of approximately 83% in classifying extraction versus nonextraction cases. Notably, features such as U-crowding, L-crowding, SN-palatal plane, SNA, FMA, molar relation, total facial height, lower facial height, and facial axis-Ricketts were most influential in achieving accuracy rates comparable to traditional methods.

Soft-tissue profile changes in adult patients treated with premolar extractions

INTRODUCTION

The objective of this study was to identify the soft-tissue profile changes and the potential pretreatment cephalometric parameters that clinicians could use to predict the lip response after premolar extraction treatment in adult patients.

METHODS

Pretreatment and posttreatment lateral cephalograms of 75 white patients treated with premolar extractions were analyzed. The following initial cephalometric measurements were recorded: upper and lower lip to E-plane, vermilion thickness, lip length, maxillary and mandibular incisor inclination, and mentolabial and nasolabial angle. Pretreatment and posttreatment radiographs were superimposed using the Björk structural method to record lip retraction and incisor/lip retraction ratio. Pearson correlation and Kruskal-Wallis tests were used to compare lip retraction and incisor/lip retraction ratio with the cephalometric variables. The sample was divided according to different extraction patterns.

RESULTS

The mean upper and lower lip retraction values were 1.4 mm and 1.7 mm, respectively. Vermilion thickness showed a negative and statistically significant correlation (P <0.05) with lip retraction and incisor/lip retraction ratio. In addition, the mean incisor/lip retraction ratio was 61% and 98% for the upper and lower thin lip, respectively, whereas the mean incisor/lip retraction ratio was 17% and 44% for the upper and lower thick lip, respectively. The comparison among extraction patterns did not highlight any noticeable difference.

CONCLUSIONS

The choice of a specific extraction pattern did not impact lip response. The vermilion thickness was the key factor influencing lip retraction: an increase in this parameter was related to a decrease in lip retraction and vice versa.

Interproximal Reduction Facilitating Orthodontic Teeth Extraction

Extractions are routinely performed in orthodontics to gain space for teeth alignment. Crowded, malaligned, and overlapped teeth make it difficult for the dental surgeon to engage the beaks of the extraction forceps on the concerned tooth for extraction. An improper grip often leads to complications of instrument slippage, crown fracture, and more commonly, luxation of adjacent teeth. This article aims to help with atraumatic orthodontic extractions and reduce such complications. This case report examines an interproximal reduction technique using standard grit, taper, flat-end diamond bur (Mani TF-20, ISO 171/014, Mani, Inc., Tochigi, Japan) for the tooth to be extracted to create enough space for proper placement of the forceps and to prevent injury to adjacent structures. It can be useful for orthodontic extractions or other cases of tooth extractions with inadequate access.

Efficiency of photobiomodulation on accelerating the tooth movement in the alignment phase of orthodontic treatment-A systematic review and meta-analysis

Objectives

To investigate the efficiency of photobiomodulation on accelerating the tooth movement in the alignment phase of orthodontic treatment.

Materials and methods

The data search was performed with PubMed, Embase, Scopus, and the Cochrane Library. Randomized clinical trials and controlled clinical trials evaluating the efficiency of photobiomodulation on accelerating tooth movement in the alignment phase were selected, and the characteristics of the included studies were collected in a customized data form. Data analysis was conducted by the random-effects model after risk of bias and certainty of evidence were assessed.

Results

Five randomized clinical trials and three controlled clinical trials were included in the final analysis. All included studies reported positive results except the study of Shehawy et al. The results of the analysis showed that photobiomodulation significantly increased the rate of tooth movement and reduced the treatment duration, compared with the control group. Although the heterogeneity was large among the included studies, it was improved after subgroup analysis.

Conclusions

This systematic review offered evidence that photobiomodulation can accelerate tooth movement in alignment procedures and reduce treatment time. Future studies are needed to find the best PBM protocol for orthodontic practice.

Cephalometric predictors for optimal soft tissue profile outcome in adult Asian class I subjects treated via extraction and non-extraction. A retrospective study

OBJECTIVE

The aim of this retrospective study was to identify cephalometric predictors associated with favourable soft tissue profile outcomes after premolars extraction and non-extraction in class I malocclusion subjects.

MATERIALS AND METHODS

A total of 80 subjects, treated with non-extraction and premolars extraction (40 subjects each), were equally divided into favourable (FG) and unfavourable (UFG) groups using subjective and objective soft tissue profile outcome assessment methods. An independent t-test was utilized for the comparison of cephalometric measurements between the non-extraction (NE) and premolars extraction (PME) treatment modalities. Cox proportional hazard algorithm regression analysis was performed to identify cephalometric factors associated with favourable soft tissue outcomes.

RESULTS

The pre-treatment mean age of the NE group was 20.2±2.3 and PME group was 20.2±2.5 years. After dividing the sample of the NE and PME groups according to subjective and objective soft-tissue outcome assessment criteria, FG and UFG consisted of 20 subjects each. Cox proportional hazard algorithm regression analysis found upper incisor to NA angle (95% CI: 1.033, 1.196) to be associated with FG in NE and upper incisor to SN (95% CI: 1.018, 1.206) and ANB angle (95% CI:1.165, 3.608) in PME. There was a statistically significant strong correlation between subjective and objective evaluation methods (P≤0.001).

CONCLUSIONS

Cephalometric analysis is a valuable tool to predict soft-tissue outcomes after NE and PME. Increased upper incisors inclinations at the start of NE treatment result in favourable soft tissue profile outcomes. Slightly convex profile and proclined maxillary incisors are the predictors of favourable soft tissue profile outcome after PME. There was a statistically significant association between subjective and objective evaluation criteria of soft tissue outcomes.

Five years review of extraction frequencies at S.D.M. College of dental sciences and Hospital in orthodontic department

Background

To find out the frequency of extraction in general, in Class I, Class II Class III patients, and to compare the frequency of extraction among sex and age.

Material and Methods

550 cases were selected retrospectively having detailed case history, complete records of facial photographs, lateral cephalogram, orthopantomographs and study models. Frequency of extraction was evaluated separately for class I, class II and class III malocclusion and for sex and ages, using the records collected.

Results

Show that there was 59.80% of extraction in general. Comparison of sex shows that there were 66.60 of extraction in females. The mean age of males for extraction was 17.85 +/- 4.18 and the mean age of females was 18.36 +/_ 4.89. Among all the groups, Class I malocclusion shows 89% of extraction.

Conclusions

There was higher frequency of extraction comprising in general. Comparison of sex shows that there was higher frequency of extraction in females. Comparison of age shows that extraction frequency is more in late adolescent period. Among all the groups, Class I malocclusion shows higher frequency of extraction.

Key words:Extraction, frequency, malocclusion.raumatic neuroma; palisaded encapsulated neuroma; oral palisaded encapsulated neuroma.

The extraction of first, second or third permanent molar teeth and its effect on the dentofacial complex

The extraction of permanent molar teeth was first introduced in 1976 as a substitution for premolar extraction in cases with mild crowding. Since then, a number of studies have investigated the effect of permanent molar extraction on dentofacial harmony. Undertaking the procedure of molar extraction is most commonly recommended in response to factors such as: gross caries, large restorations and root-filled teeth, along with its application in the management of anterior open bite and reduction in crowding in facial regions. It has been indicated, however, that before undertaking the extraction of molar teeth it is important to investigate the potential influence of the procedure on other molars, with particular consideration of their eruption path. This is due to the doubt as to the effect of the exact molar teeth extraction and their consequences. In light of this, This review was undertaken to investigate and compare the effect of first, second and the third molar teeth extraction and their subsequent dentofacial complex changes.

Factors affecting treatment decisions for Class I malocclusions

INTRODUCTION

Orthodontic treatment planning requires skill and expertise with considerable practice variations. The aims of this study were to review retrospectively the pretreatment records of patients with Class I malocclusion and to identify variables that could play a role in the treatment decision.

METHODS

From the available records of 1500 orthdontic patients, the pretreatment records of 202 patients were selected at random. Inclusion and exclusion criteria were applied, and the surviving records were divided into extraction (n = 92) and nonextraction (n = 92) treatment groups. Skeletal, dental, and soft tissue measurements were obtained from pretreatment lateral cephalograms and dental casts of subjects with bilateral Class I molar relationships. Data were statistically analyzed by binary logistic regression tests.

RESULTS

The results showed that the variables of lower anterior facial height, E-plane to upper lip, and maxillary and mandibular incisor inclinations were significantly increased in the extraction group (P <0.05), whereas spacing in the mandibular arch and increased overbite were statistically significant in the nonextraction treatment group (P <0.05). According to the model, the odds of nonextraction treatment are 1.29 and 1.24 times that of extraction treatment for every 1-mm increase in overbite and spacing in the mandibular arch, respectively.

CONCLUSIONS

Vertical facial pattern, overbite, mandibular tooth size-arch length discrepancy, lip position, and maxillary and mandibular incisor inclinations are a few of the important variables that should not be overlooked when planning orthodontic treatment. The findings of this study could facilitate the treatment planning process for patients with Class I malocclusion.

Extraction frequencies at a university orthodontic clinic in the 21st century: Demographic and diagnostic factors affecting the likelihood of extraction

INTRODUCTION

The aims of this study were to report contemporary orthodontic extraction frequencies at a university center and to investigate what patient-related factors might influence the likelihood of extraction.

METHODS

The records of 2184 consecutive patients treated at the University of North Carolina from 2000 to 2011 were analyzed. Year-by-year rates for overall orthodontic extractions and for extraction of 4 first premolars were calculated. Logistic regression, adjusting for all recorded patient risk factors for extraction, was used to examine both the changes in extraction frequencies over time and the influence of individual patient factors on the odds of extraction.

RESULTS

Small linear decreases in orthodontic extraction frequency overall (OR, 0.91; 95% CI, 0.88-0.95) and in extraction of 4 first premolars (OR, 0.95; 95% CI, 0.90-0.99) were seen. The overall extraction rate was 37.4% in 2000, and it fell just below 25% from 2006 onward. Four first premolar extraction rates ranged from 8.9% to 16.5%. Extractions were significantly more likely as crowding and overjet increased (OR, 1.2; 95% CI, 1.14-1.25; OR, 1.1; 95% CI. 1.07-1.19), as overbite decreased (OR, 0.8; 95% CI, 0.77-0.89), with Class II dental or skeletal relationships (OR, 1.5; 95% CI, 1.12- 2.05; OR, 1.4; 95% CI, 1.04-1.85), and for nonwhite patients (OR, 3.0; 95% CI, 2.2-4.06 for other races; OR, 4.1; 95% CI, 3.03-5.66 for African Americans).

CONCLUSIONS

Extractions were just as likely to be associated with Class II dental and skeletal problems and with open-bite problems as with crowding alone.

Extractions, retention and stability: the search for orthodontic truth

Background and objectives

From the beginnings of modern orthodontics, questions have been raised about the extraction of healthy permanent teeth in order to correct malocclusions. A hundred years ago, orthodontic tooth extraction was debated with almost religious intensity by experts on either side of the issue. Sheldon Friel and his mentor Edward H. Angle both had much to say about this controversy. Today, after significant progress in orthodontic practice, similar arguments are being voiced between nonextraction expansionists and those who see the need for tooth extractions in some orthodontic patients. Furthermore, varying concepts of mechanical retention of treatment results have evolved over the years which have been misinterpreted as enhancing natural orthodontic stability.

Materials and methods

In this essay, representing the Ernest Sheldon Friel Memorial Lecture presented in 2016 at the 92nd Congress of the European Orthodontic Society, a full spectrum of evidence from biology, anthropology and history is critically discussed in the search for truth among highly contested orthodontic variables: extraction versus nonextraction, fixed retention versus limited retention, and rationalized stability versus biological homeostasis.

Conclusions and implications

Conscientious clinicians should try to develop individualized treatment plans for their patients, and not be influenced by treatment 'philosophies' with untested claims in clinical orthodontics.

Frequency of orthodontic extraction

INTRODUCTION

The option of dental extraction for orthodontic purposes has been debated for more than 100 years, including periods when it was widely used in treatment, including the present, during which other methods are used to avoid dental extractions. The objective was to analyze the frequency of tooth extraction treatment performed between 1980 and 2011 at the Orthodontic Clinic of Universidade Estadual do Rio de Janeiro (UERJ).

MATERIAL AND METHODS

The clinical records of 1484 patients undergoing orthodontic treatment were evaluated. The frequency of extractions was evaluated with regard to sex, Angle's classification, the different combinations of extractions and the period when orthodontic treatment began. Chi-square test was used to determine correlations between variables, while the chi-square test for trends was used to assess the frequency of extractions over the years.

RESULTS

There was a reduction of approximately 20% in the frequency of cases treated with tooth extraction over the last 32 years. The most frequently extracted teeth were first premolars. Patients with Class I malocclusion showed fewer extractions, while Class II patients underwent a higher number of extraction treatment. There were no statistically significant differences with regard to sex.

CONCLUSION

New features introduced into the orthodontic clinic and new esthetic concepts contributed to reducing the number of cases treated with dental extractions. However, dental extractions for orthodontic purposes are still well indicated in certain cases.

Nonextraction treatment of a skeletal Class III adolescent girl with expansion and facemask: long-term stability

This article describes the combined use of maxillary expansion and a protraction facemask in the correction of a skeletal Class III malocclusion after the patient's pubertal growth spurt. Treatment efficacy and the effects on facial and smile esthetics are presented. The nonextraction option with an arch-size increase and stability issues is discussed.

Frequency evaluation of different extraction protocols in orthodontic treatment during 35 years

BACKGROUND

Studies that show frequencies of different orthodontic treatment protocols can be used as valuable parameters in the interpretation of treatment tendency with time. The purpose of this retrospective study was to evaluate all orthodontic treatment planning conducted at the Orthodontic Department at Bauru Dental School, University of São Paulo, Brazil, since 1973, in order to investigate extraction and non-extraction protocol frequencies selected at each considered period.

METHODS

The sample comprised 3,413 records of treated patients and was evaluated according to the protocol choice, divided into 10 groups: Protocol 0 (non-extraction); Protocol 1 (four first premolar extractions); Protocol 2 (two first maxillary and two second mandibular premolars); Protocol 3 (two maxillary premolar extractions); Protocol 4 (four second premolars); Protocol 5 (asymmetric premolar extractions); Protocol 6 (incisor or canine extractions); Protocol 7 (first or second molar extractions); Protocol 8 (atypical extractions) and Protocol 9 (agenesis and previously missing permanent teeth). These protocols were evaluated in seven 5-year intervals: Interval 1 (1973 to 1977); Interval 2 (1978 to 1982); Interval 3 (1983 to 1987); Interval 4 (1988 to 1992); Interval 5 (1993 to 1997); Interval 6 (1998 to 2002); Interval 7 (2003 to 2007). The frequency of each protocol was compared between the seven intervals, using the proportion test (P < 0.05).

RESULTS

The results showed that 10 protocol frequencies were significantly different among the 7 time intervals.

CONCLUSIONS

The non-extraction protocol frequency increased gradually with consequent reduction of extraction treatments. The four premolar extraction protocol frequency decreased gradually while the two maxillary premolar extraction protocol has maintained the same frequency of indications throughout time.

Extraction decision and identification of treatment predictors in Class I malocclusions

BACKGROUND

The extraction rate in orthodontics varies throughout the years. While the extraction decision is easily made or excluded in clear-cut cases, it still remains controversial what makes an orthodontist decide to extract in borderline cases. The aim of this retrospective study was to identify the percentage of extraction cases in a large group of Class I malocclusions and to clarify which variables contributed most to the extraction decision.

METHODS

The sample consisted of 542 randomly selected records of Class I patients treated in a university graduate program and in five private orthodontic offices. Of these patients, 331 were female and 211 male. The mean age was 14.55 (standard deviation (SD) 5.36) for the non-extraction group and 14.52 (SD 4.86) for the extraction group. The extensive series of 32 linear and angular measurements derived from the cephalometric analysis and the dental casts, along with the variables of age and gender, fueled a stepwise discriminant analysis.

RESULTS

The percentage of the patients treated with four first premolar extractions was 26.8%. The results showed that the variables of lower crowding, lower lip to E-plane, upper crowding, and overjet accounted most for the decision to extract at a very significant level (Sig. 0.000). The discriminant analysis assigned a classification power of 83.9% to the predictive model (p<0.0001). Fisher's linear discriminant functions provided a mathematical model, according to which any case can be classified into the adequate treatment group.

CONCLUSIONS

In a large contemporary sample of 542 Class I patients, the extraction rate was 26.8%. The most important measurements when the orthodontist decides extractions in Class I cases are lower crowding, lower lip to E-plane, upper crowding, and overjet. In clinical orthodontic practice, the findings facilitate treatment by providing evidence-based treatment predictors for Class I malocclusions.

Human dental pulp stem cells expressing transforming growth factor β3 transgene for cartilage-like tissue engineering

BACKGROUND AIMS

The aim of this study was to engineer sizable three-dimensional cartilage-like constructs using stem cells isolated from human dental pulp stem cells (DPSCs).

METHODS

Human DPSCs were isolated from teeth extracted for orthodontic treatment and enriched further using immuno-magnetic bead selection for stem cell marker CD146. Chondrogenic lineage differentiation of DPSCs induced using recombinant transforming growth factor β3 (TGFβ3) was verified by pellet culture. Because the use of recombinant proteins is associated with rapid degradation and difficult in vivo administration, we constructed the recombinant adeno-associated viral vector encoding human TGFβ3 and determined the best multiplicity of infection for DPSCs. Transduced DPSCs were seeded on poly-l-lactic acid/polyethylene glycol (PLLA/PEG) electrospun fiber scaffolds demonstrating proper attachment, proliferation and viability as shown by scanning electron microscopy micrographs and CCK-8 cell counting kit. Scaffolds seeded with DPSCs were implanted in the back of nude mice.

RESULTS

Transduced DPSCs highly expressed human TGFβ3 for up to 48 days and expressed chondrogenic markers collagen IIa1, Sox9 and aggrecan, as verified by immunohistochemistry and messenger RNA (mRNA). Immunohistochemistry for TGFβ3/DPSC constructs (n = 5/group) showed cartilage-like matrix formation with glycosaminoglycans. In vivo constructs with TGFβ3/DPSCs showed higher collagen type II and Sox9 mRNA expression relative to non-transduced DPSC constructs (n = 5/group). Western blot analysis confirmed this expression pattern on the protein level (n = 3/group).

CONCLUSIONS

Immuno-selected DPSCs can be successfully differentiated toward chondrogenic lineage, while expressing the chondrogenic inducing factor. Seeded on PLLA/PEG electrospun scaffold, human DPSCs formed three-dimensional cartilage constructs that could prove useful in future treatment of cartilage defects.

Treatment of a severe arch-length deficiency with anteroposterior and transverse expansion: long-term stability

This article describes the nonextraction treatment of a girl in the late mixed dentition with a severe arch-length deficiency. Rapid maxillary expansion and molar distalization were combined with a lip bumper in the mandible, followed by fixed appliances. Although the literature has reported a high rate of relapse with this method of treatment, excellent stability was achieved at 5 years 3 months posttreatment. The merits of extraction vs nonextraction treatment and stability are discussed.

Applications of microscale technologies for regenerative dentistry

While widespread advances in tissue engineering have occurred over the past decade, many challenges remain in the context of tissue engineering and regeneration of the tooth. For example, although tooth development is the result of repeated temporal and spatial interactions between cells of ectoderm and mesoderm origin, most current tooth engineering systems cannot recreate such developmental processes. In this regard, microscale approaches that spatially pattern and support the development of different cell types in close proximity can be used to regulate the cellular microenvironment and, as such, are promising approaches for tooth development. Microscale technologies also present alternatives to conventional tissue engineering approaches in terms of scaffolds and the ability to direct stem cells. Furthermore, microscale techniques can be used to miniaturize many in vitro techniques and to facilitate high-throughput experimentation. In this review, we discuss the emerging microscale technologies for the in vitro evaluation of dental cells, dental tissue engineering, and tooth regeneration.

Patients' perceptions of recovery after routine extraction of healthy premolars

INTRODUCTION

In this prospective study, we evaluated patients' perceptions of recovery after orthodontic premolar extractions.

METHODS

Thirty patients (18 girls, 12 boys, mean age 14.6 +/- 3.8 years) were given a health-related quality of life questionnaire to be completed each postoperative day (POD) for 7 days. The questionnaire was designed to assess each patient's perception of recovery: pain, oral function, general activity measures, and other variables. The impact of possible predictor variables, such as age, sex, length of surgical procedure, number of simultaneous extractions, and time during the day, was assessed.

RESULTS

Severe pain (16.7%, 3.3%) and consumption of analgesics (70%, 13.2%) declined dramatically from POD 1 to POD 2. Improvements in oral function and other symptoms were evident by POD 2. Absence from school resembled interference in daily activities (POD 2). Age was the most significant predictor variable, with results showing delayed recoveries for patients older than 15 years. The most striking differences were reported for enjoying food (P <.05), taste (P <.05), and food stagnation (P <.05). The number of extractions performed at the same appointment had no affect on posttreatment recovery.

CONCLUSIONS

This study was designed to provide baseline health-related quality of life information with which to compare other surgical procedures frequently needed in orthodontic treatment, such as removal of third molars and exposure of impacted teeth. Additionally, it provides information for patients and clinicians on postoperative recovery after premolar orthodontic extractions.

The three-dimensional effects of orthodontic treatment on the facial soft tissues--a preliminary study

OBJECTIVE

To examine the three-dimensional effects of extraction and non-extraction orthodontic treatment on the facial soft tissues.

SETTING

Department of Orthodontics, Royal London Hospital.

DESIGN

Longitudinal study of two prospective cohorts of patients who were attending for orthodontic treatment. METHOD 12 patients were included in each group, in accordance with the selection criteria. Three-dimensional optical surface scans of these patients were obtained in the one month prior to having fixed appliances placed and this was repeated at the end of treatment.

RESULTS

The average face of the non-extraction patients was of greater general dimensions than the extraction average, both at the start and the end of treatment. During the fixed appliance treatment, the vermilion of the upper lip became more protrusive to a similar extent in both groups in relation to the reference plane. The lower lip vermilion and the philtrum showed no change for either group over the treatment time. The labiomental fold area showed a slightly greater forward movement in the extraction group with treatment.

CONCLUSION

Three-dimensional optical surface scanning allows data from the whole of the face to be assessed, as opposed to the lateral profile view used in the majority of the studies to date. The effects of the two types of treatment on the facial soft tissues were very similar, indicating that orthodontic treatment involving the extraction of teeth does not have a detrimental effect on the face.

A longitudinal evaluation of extraction versus nonextraction treatment with special reference to the posttreatment irregularity of the lower incisors

A tendency exists in contemporary orthodontics to pursue a completely non-extraction philosophy. Moreover, it has been shown that the extraction versus non-extraction debate is still with us. Controversy exists as to which treatment decision will eventually lead to orthodontic stability. It is thus imperative to conduct investigations on long-term changes of the dentition in both treatment regimens. The present study serves as an example of such a longitudinal study. A random sample, inclusive of both extraction and non-extraction treatments, was examined with respect to long-term stability and an assessment was made as to whether one treatment option favors success over the other. It was concluded that the correct initial treatment choice will not only lead to correction of the malocclusion, but will also ensure clinically acceptable stability with no significant differences between extraction and non-extraction treatments.

On the management of extraction sites

Extraction sites may be needed to achieve specific orthodontic goals of positioning the dentition within the craniofacial complex. The fundamental reality that determines the final position of the dentition, however, is the control exercised by the clinician in closure of the extraction sites. A specific treatment objective may require the posterior teeth to remain in a constant position anteroposteriorly as well as vertically, while the anterior teeth occupy the entire extraction site. Another treatment objective may require the reverse, or any number of purposeful alternatives of extraction site closure. An appliance system developed over time, which provides this control, is described. The system takes advantage of aspects of continuous arch therapy that provides constant, positive orientation of the anterior and posterior groups of teeth to each other in three-dimensional space across an extraction site, combined with aspects of the segmented arch technique that permit definable and predictable force systems to be applied to these teeth. Consequently, the clinician has the ability to forecast treatment outcomes with confidence.

The duration of orthodontic treatment with and without extractions: a pilot study of five selected practices

Contemporary orthodontic practice is diverse, both in the variety of clinical problems treated and in the methods used. Practices differ with respect to their patient composition as well as in many variables relative to treatment protocols. Such heterogeneity makes it difficult to make valid generalizations concerning the characteristics of orthodontic treatment procedures or outcomes; yet data and methods are required for assessment of issues of efficacy and utility. The frequency of orthodontic extractions is an objective criterion that distinguishes practices and may also be related to differences in treatment outcome variables, such as duration. Following a telephone survey to estimate extraction rates in the practices of 238 Michigan orthodontists, five practices with very high or low reported rates were chosen for this pilot study. Our primary aim was to determine whether a systematic relationship existed between the relative frequency of extraction treatments and the duration of active appliance therapy. Records of 438 patients from these practices were examined. The extraction rates of the practices ranged from a low of 25% to a high of 84%. Treatment duration was affected by several variables, such as the number of arches treated, the number of treatment phases, and the practice selected. When the data for all five practices were pooled, and all of the extraction versus nonextraction treatments were compared, the mean durations of treatment were 31.2 and 31.3 months, respectively. Data from individual practices, however, indicated that extraction treatment in each of the practices was of longer duration than nonextraction therapy. These differences in duration were 3.0, 6.6, 2.4, 3.0, and 7.3 months in the five practices.(ABSTRACT TRUNCATED AT 250 WORDS)

The prevalence of orthodontic extractions

The controversy regarding extractions for orthodontic treatment continues and today is invoked by some as a feature of the "standard of care." For this and other reasons, it is necessary to have contemporary data on the general prevalence of orthodontic extractions and the interpractice range of extraction rates in current specialty practice and, if possible, also to establish possible reasons for, and consequences of, the extraction versus nonextraction decision. Although all treatment decisions are made on a case-by-case basis, practitioners appear to have personal preferences for or against extractions and hence adopt policies with different degrees of aversion to or bias toward extraction therapy. A number of factors enter into the extraction decision. These include features of the malocclusion, objectives of treatment, and the technique selected to accomplish desired results. The present study does not address such issues but merely serves to provide epidemiologic data to estimate extraction frequency in contemporary orthodontic practice. Accordingly, a telephone survey of all licensed orthodontists in Michigan was conducted to determine their subjective estimates of extraction rates for patients in their practices. There were 238 respondents, for a response rate of 90.2%. Reported rates range from 5% to 87%. We then selected five practices from the extremes of the reported extraction rates. Three practices from the high end and two from the low end were included for an examination of patient records. Records of a total of 438 patient whose treatment had been completed were reviewed. The actual extraction rates for these practices ranged from 25% to 85%, which differed considerably from the clinicians' subjective estimates.(ABSTRACT TRUNCATED AT 250 WORDS)

Cross-sectional study of orthodontic treatment and missing of permanent teeth in two birth cohorts of Finnish students according to sex

Undergraduate students (n = 451) at a Finnish university were studied. For analysis, the subjects were divided into two birth cohorts: those born before 1955, and those born in that year or later. Information about previous orthodontic appliance therapy was obtained from the students by using a structured questionnaire. Missing permanent teeth (second and third molars excluded) were recorded at a dental examination. Every 10th student had received orthodontic treatment; the proportion of orthodontically treated subjects was higher for females (14%) than for males (5%). Seven percent of students born in 1954 or earlier and 15% of the younger students had had orthodontic treatment before 1977. In 39% of subjects, at least one permanent tooth was missing while only 12% had lost more than two permanent teeth. The tooth missing most often was the permanent mandibular first molar (in 23% of subjects). Frequency of tooth loss was the same in males and females. At least one permanent tooth was missing in 48% of the older and in 31% of the younger students. At least one first molar had been lost by 36% of the older students and 20% of the younger ones. Fewer first molars but more permanent teeth anterior to the first molars were missing in subjects who had had orthodontic treatment than in subjects who had not had such treatment. Among Finnish students the frequency of extraction of permanent teeth because of caries is decreasing, and the frequency of orthodontic treatment is increasing. Females are more likely to seek orthodontic treatment than males are.

Changes in orthodontic treatment patterns within one orthodontic practice over a 15 year period

Fifty consecutive treatment case records were analysed for each of the years 1964, 1971, 1974, 1976 and 1978. The following variables were examined: sex distribution, age at start of treatment, extractions undertaken (if any), type of appliance used, completeness or incompleteness of treatment, treatment duration and one final category termed "other clinical procedures' dealing with cephalometry, photography and surgery. The sex distribution fluctuated only slightly with a predominance of females throughout. The age of onset of treatment was fairly constant at around 12 years. Over the 15 years a rise in number of non-extraction cases was noted and the number of patients treated by extraction only, fell. The use of fixed appliances increased steadily and in 1978 55 per cent of cases received some form of fixed appliance therapy. The mean number of incomplete cases was 17 per cent for all years with no rise latterly despite the use of more complex appliances. The treatment duration time showed a steady decrease over the 15 year period. Few referrals for oral surgery were made, although the use of precision following rotation correction has increased.