Three-dimensional space changes after premature loss of a maxillary primary first molar

Background.  A space maintainer is generally preferred when a primary first molar is lost before or during active eruption of the first permanent molars in order to prevent space loss. However, controversy prevails regarding the space loss after eruption of the permanent first molars.
Aim.  The purpose of this study was to examine spatial changes subsequent to premature loss of a maxillary primary first molar after the eruption of the permanent first molars.
Design.  Thirteen children, five girls and eight boys, expecting premature extraction of a maxillary primary first molar because of caries and/or failed pulp therapy, were selected. Spatial changes were investigated using a three-dimensional laser scanner by comparing the primary molar space, arch width, arch length, and arch perimeter before and after the extraction of a maxillary primary first molar. Also, the inclination and angulation changes in the maxillary primary canines, primary second molars, and permanent first molars adjacent to the extraction site were investigated before and after the extraction of the maxillary primary first molar in order to examine the source of space loss.
Results.  There was no statistically significant space loss on the extraction side compared to the control side ( P  = 0.33). No consistent findings were seen on the inclination and angulation changes on the extraction side.
Conclusions.  The premature loss of a maxillary primary first molar, in cases with class I molar relationship, has limited influence on the space in permanent dentition.     

变异式保持器治疗第一恒磨牙异位萌出的临床应用

目的探讨变异式保持器治疗第一恒磨牙异位萌出的临床应用效果。方法选择临床25例上颌第一恒磨牙异位萌出的患儿,年龄7~9岁,其中10例双侧,15例单侧,通过传统的Nance弓焊接远端牵引钩,在异位萌出的第一恒磨牙牙合面,联合应用链状橡皮圈推第一恒磨牙向远中以达到其正常的生理位置。结果 25例接受治疗的患儿均完成了治疗,且疗效明显,异位的第一恒磨牙均萌出到了正常位置。结论变异式保持器用于治疗第一恒磨牙异位萌出疗效显著,操作简便,适合在临床推广。     

Ectopic eruption of the maxillary first permanent molar: etiologic factors

For clinical handling, it is important to determine whether any etiologic factors, alone or in combination, are of more importance than others in causing ectopic eruption of a maxillary first permanent molar. Etiologic factors involved in ectopic eruption of maxillary first permanent molars were investigated in 129 children with a mean age of 8.6 years. Ninety-two children (fifty-eight boys and thirty-four girls) had ectopic eruption and thirty-seven children served as controls and were matched by age and sex. Two types of ectopic eruption could be distinguished: a reversible type in which the permanent molar frees itself and an irreversible type in which the permanent molar remains in a locked position. Measurements were made on lateral head films, orthopantomograms, and dental casts. For 104 subjects all variables could be measured. Data was analyzed by discriminant analysis. Children with irreversible ectopic eruption had significantly larger permanent molars and a more pronounced mesial angle of eruption. A tendency toward a shorter maxilla was also found. No significant difference was found between sides with reversible ectopic eruption and sides with normal eruption. From the discriminant analysis between groups and all variables investigated, 90.7 percent of the cases could be correctly classified into groups. This study indicates that sufficient space may be gained for the premolars if the mesial tipping of the first molar is corrected, despite the tendency toward a shorter maxilla and larger than normal permanent molars.     

Immediate and six-month space changes after premature loss of a primary maxillary first molar

BACKGROUND: Premature loss of primary maxillary first molars has been associated with a number of consequences (such as tipping of the first permanent molar). The aim of the authors' study was to investigate dental-arch space problems arising as a result of premature loss of a primary maxillary first molar. METHODS: This study was composed of 19 children who experienced unilateral premature loss of a primary maxillary first molar. The authors used each patient's intact contralateral arch segment as a control. The authors obtained maxillary dental study casts two or three days after the tooth was extracted, as well as six months later. RESULTS: The D + E space from the extraction side six months after removal of the tooth (mean +/- standard deviation, 15.62 +/- 1.13 millimeters) was significantly smaller than the space on the control side (16.88 +/- 1.12 mm) and the initial D + E space (16.70 +/- 0.69 mm). The authors found a significantly shorter arch length (25.47 +/- 1.58 mm) and larger intercanine width (31.29 +/- 2.49 mm) six months after the tooth was extracted compared with the initial arch length (25.66 +/- 1.64 mm) and intercanine width (30.42 +/- 2.64 mm). CONCLUSIONS: The early space changes to the maxillary arch subsequent to premature loss of a primary maxillary first molar are primarily distal drift of the primary canines toward the extraction space and palatal migration of the maxillary incisors. Although 1 mm of space was lost, which is statistically significant, this is not likely to be of sufficient clinical significance to warrant use of a space maintainer. If palatal movement appears to be needed, the dentist should consider use of a palatal arch rather than a band-and-loop maintainer. CLINICAL IMPLICATIONS: The effects of space maintainers need to be re-evaluated in cases of unilateral premature loss of a primary maxillary first molar.     

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第一恒磨牙在萌出过程中过于偏近中可导致第二乳磨牙牙根吸收。第一恒磨牙异位萌出常常造成间隙丧失和牙弓长度减少，严重者可导致第二乳磨牙早失。第一恒磨牙异位萌出分为可逆性和不可逆性，对于不可逆性异位萌出应进行积极的治疗。治疗方法包括主动治疗和被动治疗。前者常用的方法有分牙法以及采用推第一恒磨牙向后的装置；后者通常采用截冠或拔牙的方法。本文对第一恒磨牙异位萌出的临床表现和常用的治疗方法进行了阐述。     

The not-so-harmless maxillary primary first molar extraction

BACKGROUND: Premature loss of primary molars has been associated with space loss and eruptive difficulties, especially when the loss occurs to the primary second molars and when it occurs early. This has not been thought to be the case for primary first molars. METHODS: The author revisited 13 cases from an earlier study on the effects of premature loss of maxillary primary molars. These longitudinal cases were scrutinized, using serial panoramic radiographs, to explain the irregular response in terms of dental migration. The author presents two case reports. RESULTS: In the earlier study, the author used digitized study casts and the concept of D + E space--the space occupied by the primary first and second molars--to describe the dental migration that occurred after premature tooth loss. Using analysis of variance on data generated using an instrument capable of measuring in tenths of millimeters, the author produced findings regarding the amount of space loss, rate of space loss, effect of age at loss, amount of space regained at the time of replacement by the permanent tooth and effect on Angle's classification. Finally, the author created a simulation describing directional change; this revealed that the maxillary primary first molar loss resulted in a mesial displacement of the permanent canine during eruption. CONCLUSIONS: When the maxillary primary first molar is lost prematurely, the first premolar erupts in a more mesial direction than normal, as a result of the mesial incline of the primary second molar, and consumes the space of the permanent canine, which becomes blocked out. CLINICAL IMPLICATIONS: Rather than use a space maintainer after the premature loss of the maxillary primary first molar, the author suggests, clinicians can choose from a number of other options for preventing the first premolar from erupting too far in a mesial direction.     

Dentoskeletal effects induced by rapid molar distalization with the first class appliance.

The purpose of this study was to evaluate the treatment effects of the first class appliance (FCA; Leone, Firenze, Italy), a new intraoral device for unilateral or bilateral rapid molar distalizaton. A retrospective study was conducted to compare the predistalization and postdistalization cephalograms of 17 patients (10 male, 7 female) with Class II malocclusions treated with the FCA. Mean age at the start of treatment was 13 years 4 months. The FCA produced rapid molar distalization, and the bilateral Class II molar relationship was corrected in 2.4 months, on average. Maxillary molar distalization contributed to 70% of the space created anterior to the first molars; 30% of the space was due to reciprocal anchorage loss of the maxillary second premolars. The maxillary first molars showed a significant distalization of 4.0 mm, associated with a significant distal axial incline of 4.6 degrees and a significant extrusion of 1.2 mm. As for anchorage loss, the second premolars exhibited a significant mesial movement of 1.7 mm, associated with a significant mesial axial incline of 2.2 degrees and a nonsignificant extrusion of 1.0 mm. In the anterior region, a significant mesial movement of the maxillary incisor of 1.3 mm was associated with a significant incisor proclination (2.6 degrees ) and a significant increase in overjet (1.2 mm). No significant changes in either sagittal or vertical skeletal relationships were observed. The results suggest that the FCA is an efficient and reliable device for distalizing the maxillary permanent first molars.     

Ectopic eruption of the maxillary second molar: Predictive factors

Objective:The purpose of this study was to investigate the diagnostic aspects, contributing conditions, and predictive key factors associated with ectopic eruption of maxillary second molars.Material and Methods:This retrospective study evaluated the study models, lateral cephalographs, and panoramic radiographs of 40 adult subjects (20 men, 20 women) with bilateral ectopic eruption and 40 subjects (20 men, 20 women) with normal eruption of the maxillary second molars. Studied variables were analyzed statistically by independent t-tests, univariate and multivariate logistic regression analysis, followed by receiver-operating characteristic analysis.Results:Tooth widths of bilateral lateral incisors, canines, and premolars were wider in the ectopic group, which resulted in greater arch lengths. The ANB angle and maxillary tuberosity distance (PTV-M1, PTV-M2) were smaller in the ectopic group. The long axes of the maxillary molars showed significant distal inclination in the ectopic group. The multivariate logistic regression analysis showed that three key factors—arch length, ANB angle, and PTV-M1 distance—were significantly associated with ectopic eruption of the second molars. The area under the curve (AUC) was the largest for the combination of the three key factors with an AUC greater than 0.75. PTV-M1 alone was the single factor that showed the strongest association with ectopic eruption (AUC = 0.7363).Conclusions:An increase in arch length, decrease in ANB angle, and decrease in maxillary tuberosity distance to the distal aspect of the maxillary first molar (PTV-M1) were the most predictive factors associated with ectopic eruption of maxillary second molars.     

Unilateral correction of space loss in the mixed dentition

Distalization of maxillary molars is indicated for correction of Class II dental malocclusion and for space gain in cases of space deficiency. The ideal treatment with an intraoral fixed appliance for molar distalization should fulfill the following requirements: patient compliance; acceptable esthetics; comfort; minimum anterior anchor loss (as evidenced by inclination of incisors); bodily movement of the molars to avoid undesirable effects and unstable outcomes; and minimum time required during sessions for placement and activations. The purpose of this paper was to present an alternative treatment for space recovery in the area of the maxillary right second premolar when there has been significant mesial movement of the permanent maxillary right first molar. We used a modified appliance that allows unilateral molar distalization in cases of unilateral tooth/arch size discrepancy using the opposite side as anchor, thus reducing the mesialization of the anterior teeth.     

Orthodontic treatment for an adolescent with a history of acute lymphoblastic leukemia

This case report describes the treatment of a Class I malocclusion that involved ectopic position of the maxillary permanent left canine and the mandibular permanent right second molar. The patient was an adolescent who presented with a medical history that was remarkable for diagnosis and treatment of acute lymphoblastic leukemia (ALL). Dental history was remarkable for significant, generalized shortened roots that were more severe in the mandibular arch. The treatment included fixed appliance therapy in the maxillary arch only and surgical luxation of the mandibular second molar. Successful integration of the maxillary permanent left canine was accomplished without excessive flaring of the maxillary permanent incisors or disruption of the buccal segment occlusion. The risk of external root resorption on teeth with abnormal root morphology, as a result of fixed appliance therapy, should be weighed against the relative benefits that are expected from treatment.     

Ectopic eruption of the maxillary central permanent incisors and mandibular first permanent molars: report of an unusual case.

Ectopic eruption is a disturbance in which the tooth does not follow its usual course. Among its more important etiologic factors are macrodontism, shortened arch length, posterior positioning of the maxilla, atypical eruption angle, and genetic factors. This article reports a rare case of ectopic eruption of 4 permanent teeth, maxillary central incisors and mandibular first molars, in a child aged 7 years and 11 months, in which the treatment consisted of extracting the maxillary primary central incisors and making an orthodontic intervention on the mandibular arch. A bilateral fixed appliance containing 2 hooks with loops, 1 buccal and the other lingual, was placed on the mandibular primary first molars. The hooks were activated in a niche made of light-curing resin on the occlusal surface of the mandibular permanent molars, to bring about the distal drift of these teeth. After 6 months, complete eruption of the mandibular permanent molars occurred, and a slight displacement of the maxillary permanent central incisors toward the median line was noted. The importance of early, adequate treatment is discussed.     

Complete infraocclusion of a previously erupted primary molar: A case report

The prevalence of infraoccluded or impacted primary molars was reported to be from 1.3% to 8.9% of the population with higher incidence between siblings. This is a report of a rare case of a 10-year-and-11-month-old boy with a previously erupted primary maxillary right second molar that was restored by with an amalgam filling at about three years of age. After seven years, the said tooth was found X-ray photographically to be completely embedded into the alveolar bone with an “impacted” maxillary permanent second premolar. There was also mesial tipping of the adjacent permanent first molar. The management of this case included the use of a space regainer to correct the molar tipping, surgical removal of the ankylotic infraoccluded primary molar and the use of a palatal holding arch to correct the torsiversion. This report underscores the need for early recognition of infraoccluded/ ankylosed primary teeth by dentists for regular monitoring and timely and appropriate intervention.     

A longitudinal study on growth and development of dental arches of primary, mixed and permanent dentitions

In dental clinic for children, criteria for growth and developmental changes related to increases in the width and length of the dental arch at the primary, mixed, and permanent dentition stages are essential. This study was carried out to measure the width and the length of normal dental arch and to make detailed observations of growth and developmental processes in the dental arch at each dentition stage. Materials were serial study casts of the maxilla and the mandible taken every 2 month from 127 children (74 boys and 54 girls). The casts were made from 6 months after birth until the age of 15. Measurements of the width of the dental arch were made between bilateral teeth of the same tooth type, both deciduous and permanent. The length of the dental arch was measured on the basis of the perpendicular distance from the contact point of mesial surfaces of central incisors to a line between bilateral teeth of the same tooth type. Measured values were categorized according to either chronological age or tooth age on the basis of the eruption of the central permanent incisors. The indices of the dental arch with relation to the width and the length at each dentition stage were calculated for the sake of partial and total observations of alterations in dental arch form. The results were as follows: 1) In terms of chronological age, until 1 year before the eruption of permanent replacements, the width of the dental arch gradually decreased in both the maxilla and the mandible in the regions of the deciduous central and lateral incisors. Increasing slightly from about the age of 6 years and the period of mixed dentition, the width of the dental arch remained stable until the permanent dentition stage. From the primary dentition stage, the width of the dental arch in the region of the maxillary and mandibular canines and first and second molars gradually increased. Therefore it remained stable until the eruption of permanent dentition. The width in the region of the permanent maxillary and mandibular first molars gradually increased and attained a stable condition at about 12 years of age. In males, the width in the area of the maxillary secondary molars decreased slightly and tended to decrease in the mandible. In females, on the other hand, the width showed a tendency to increase with advancing ages. With the exception of the second permanent molars, the width between the distance of bilateral teeth were consistently larger in males than in females.(ABSTRACT TRUNCATED AT 400 WORDS)     

Association between ectopic eruption of maxillary canines and first molars

The purpose of this study was to elucidate a possible association between ectopic first molar eruption causing root resorption on the distal root of the primary maxillary second molar, and ectopic canine eruption causing root resorption on the permanent maxillary incisors.The subjects consisted of 30 patients, 22 females and eight males in the age range 8.3-15.0 years in whom root resorption of the permanent maxillary lateral and/or central incisor caused by the erupting permanent canine was diagnosed, and clinical and/or radiographic information concerning maxillary first molar eruption existed.It was found that of the 30 patients, seven (23.3 per cent) also had pathological root resorption of the second primary molar caused by ectopic molar eruption.It is suggested that patients with ectopic maxillary first molar eruption leading to pathological root resorption of the maxillary second primary molar are followed closely during the period of premolar and canine eruption, as the ectopic first molar could be an early warning of an increased risk of ectopic canine eruption leading to root resorption of the maxillary permanent incisors.     

Treatment of children with ectopic eruption of the maxillary first permanent molar by cervical traction

The sequelae of extraction of the second deciduous molar due to irreversible ectopic eruption of the maxillary first permanent molar are mesial tipping of the permanent molar and subsequent space loss. The purpose of this study was to evaluate the effects of early treatment with the Kloehn type of cervical headgear. Forty-six children with ectopic eruption were treated. The mean age at the start of treatment was 8.3 years (range, 6.5 to 9.9 years) and the mean treatment time was 0.8 year (range, 0.5 to 1.0 year). Nineteen variables from orthopantomograms, lateral head films, and dental casts were analyzed by one-way analysis of variance. The registrations were made at the start of treatment, at the end of treatment, and 1 year posttreatment. The treatment resulted in distal tipping of the first permanent molar to a good occlusion in all children. The s-n-ss angle decreased during treatment in all children, and a mean proclination of the maxillary incisors of 3 degrees was registered. Proclination was independent of the type of occlusion and was unchanged 1 year posttreatment. The ss-n-sm angle was also reduced during treatment and was unchanged 1 year posttreatment. The most favorable time for treatment seems to be when the second premolar is close to eruption or erupting at the end of the treatment period. Because of the risk of inhibited sagittal growth of the maxilla with this type of treatment, careful cephalometric evaluation is considered important before the start of treatment.     

Management of anteroposterior dental movements

Management of the anteroposterior dimension is one of the most common problems encountered in orthodontic treatment. Numerous methods are available to treat the anteroposterior discrepancy depending on the treatment objectives and the available growth potential. Some situations may require a dental correction such as maxillary molar derotation or distal movements of both the upper and lower molars. If additional arch length is required, the extraction of permanent teeth may serve as an effective treatment modality as long as the anchorage requirements are considered. Other instances may necessitate skeletal correction via growth modification ie, maintaining the maxilla anteroposteriorly during growth. Regardless of the treatment mechanics used, it is important to understand how these different methods can affect the amount of arch length gained with respect to the treatment objectives for incisor and molar position. Once the objectives for incisor and molar position are determined, then the appropriate mechanotherapy can be used.     

上颌第一恒磨牙异位萌出的片段弓治疗

目的:探讨片段弓治疗上颌第一恒磨牙异位萌出的临床应用效果.方法:纳入15例年龄7～9岁的患者,上颌第一恒磨牙异位萌出,单侧近中阻生,应用片段弓矫治技术,镍钛推簧推第一恒磨牙向远中.结果:15例患者治疗结束后,异位的上颌第一恒磨牙正常萌出.结论:片段弓矫治技术远中移动异位萌出的上颌第一恒磨牙疗效显著.     

Twelve-month space changes after premature loss of a primary maxillary first molar

International Journal of Paediatric Dentistry 2011; 21: 161–166 Background. Many early investigations concerning space changes following premature extraction of primary molars had a cross‐sectional design, a small sample size, and a somewhat crude methodology, which may have led to misunderstandings. Aim. The aim of this study was to use established longitudinal data to investigate ongoing (12‐month) dental‐arch space problems arising as a result of premature loss of a primary maxillary first molar. Design. Thirteen children (mean ± SD age at time of tooth extraction, 6.0 ± 0.74 years) with unilateral premature loss of a primary maxillary first molar were selected for this study. Maxillary dental study casts were obtained from participants 2 or 3 days after the tooth was removed, as well as at a follow‐up appointment 12 months later. Six reference lines were measured on the study cast: D + E space, arch width, arch length, intercanine width, intercanine length, and arch perimeter. For each participant, the D + E space of the contralateral intact primary molar served as a control. A paired t‐test was used to compare the cast measurements between initial examination and 12‐month follow‐up. A t‐test was used to compare D + E space changes with those of the control group. Results. The D + E space of the extraction side after 12 months was significantly smaller than that of the control side (P < 0.05) and the initial D + E space (P < 0.05). A significantly greater arch perimeter, intercanine width, and intercanine length were found after 12 months compared with the initial parameters. No significant differences were found, however, in arch width or arch length between the initial examination and the 12‐month follow‐up examination (P > 0.05). Conclusions. The 12‐month space changes in the maxillary dental arch after premature loss of a primary maxillary first molar consist mainly of distal drift of the primary canine toward the extraction site. Mesial movement of permanent molars or tilting of the primary molars did not occur. An increased arch dimension was found especially in the anterior segment (intercanine width and length). There is no need for the use of space maintainers from the results in this study in cases of premature loss of a primary first molar.