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Lorenzo Franchi - One of the best experts on this subject based on the ideXlab platform.

  • mesial rotation of upper first molars in class ii division 1 malocclusion in the mixed dentition a controlled blind study
    Progress in Orthodontics, 2011
    Co-Authors: Veronica Giuntini, Tiziano Accetti, Paola Cozza, Efisio Defraia, Lorenzo Franchi
    Abstract:

    Abstract Objective To compare the amount of upper molar rotation in subjects with Class II Division 1 malocclusion and subjects with normal occlusion in the intermediate and late mixed dentition phases. Materials and methods Dental cast measurements were performed in a sample of 120 Class II Division 1 subjects (CL2 group, 67 females and 53 males, mean age 9.4 ± 1.1 years), and in a sample of 58 Class I subjects (CL1 group, 34 females and 24 males, mean age 9.7 ± 1.2 years). Independent sample t tests were used for statistical comparisons (P  Results The amount of upper molar rotation was significantly greater in CL2 group when compared with CL1 group as assessed by both the mesial and buccal molar cusp angles. No differences were found with regard to upper or lower arch depths, or upper Intercanine Width. CL2 group showed a significant deficiency in upper intermolar Width along with a significant posterior transverse interarch discrepancy when compared with CL1 group. Conclusions Subjects with Class II malocclusion in the mixed dentition present with mesial upper molar rotation in about 84% of the cases. The correction of molar rotation may provide between 1 and 2 mm of gain in arch perimeter and of improvement in molar relationships per side in 5 out 6 Class II patients.

Yngtzer J Lin - One of the best experts on this subject based on the ideXlab platform.

  • long term space changes after premature loss of a primary maxillary first molar
    Journal of Dental Sciences, 2017
    Co-Authors: Yngtzer J Lin, Yaitin Lin
    Abstract:

    Abstract Background/purpose The consequence of premature loss of primary teeth resulting in the need for space maintainers has been controversial for many years. There is no longitudinal long-term report in literature regarding the premature loss of a primary maxillary first molar. The aim of this study was to continue observing the long-term space changes of 19 cases following premature loss of a primary maxillary first molar during the transition from primary to permanent dentition. Materials and methods Ten of the 19 original participants were excluded because of extensive decay or loss to follow-up. Nine children (mean age at time of tooth extraction, 6.0 ± 0.42 years) with unilateral premature loss of a primary maxillary first molar were examined. Maxillary dental study casts were obtained 2 days or 3 days after tooth removal and, on average, 81 months later. The contralateral intact primary molars in each participant served as controls. The arch Width, arch length, Intercanine Width, Intercanine length, and arch perimeter of each study cast from the initial and follow-up examinations were measured and compared using paired t -tests. Results Eight of nine cases (88.9%) did not show crowded permanent successors or canine block-out at the extraction site. Interestingly, the permanent dentition was more crowded at the control site (2/9) than at the extraction site (1/9). The arch Width, arch length, Intercanine Width, and Intercanine length significantly increased at 81 months (P  Conclusion The anterior and posterior arch dimensions significantly increased 81 months after premature loss of a primary maxillary first molar, which suggested that space maintainers were not needed in these cases.

  • twelve month space changes after premature loss of a primary maxillary first molar
    International Journal of Paediatric Dentistry, 2011
    Co-Authors: Yaitin Lin, Wenhsien Lin, Yngtzer J Lin
    Abstract:

    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). 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.

  • immediate and six month space changes after premature loss of a primary maxillary first molar
    Journal of the American Dental Association, 2007
    Co-Authors: Yaitin Lin, Wenhsien Lin, Yngtzer J Lin
    Abstract:

    ABSTRACT 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.

Yaitin Lin - One of the best experts on this subject based on the ideXlab platform.

  • long term space changes after premature loss of a primary maxillary first molar
    Journal of Dental Sciences, 2017
    Co-Authors: Yngtzer J Lin, Yaitin Lin
    Abstract:

    Abstract Background/purpose The consequence of premature loss of primary teeth resulting in the need for space maintainers has been controversial for many years. There is no longitudinal long-term report in literature regarding the premature loss of a primary maxillary first molar. The aim of this study was to continue observing the long-term space changes of 19 cases following premature loss of a primary maxillary first molar during the transition from primary to permanent dentition. Materials and methods Ten of the 19 original participants were excluded because of extensive decay or loss to follow-up. Nine children (mean age at time of tooth extraction, 6.0 ± 0.42 years) with unilateral premature loss of a primary maxillary first molar were examined. Maxillary dental study casts were obtained 2 days or 3 days after tooth removal and, on average, 81 months later. The contralateral intact primary molars in each participant served as controls. The arch Width, arch length, Intercanine Width, Intercanine length, and arch perimeter of each study cast from the initial and follow-up examinations were measured and compared using paired t -tests. Results Eight of nine cases (88.9%) did not show crowded permanent successors or canine block-out at the extraction site. Interestingly, the permanent dentition was more crowded at the control site (2/9) than at the extraction site (1/9). The arch Width, arch length, Intercanine Width, and Intercanine length significantly increased at 81 months (P  Conclusion The anterior and posterior arch dimensions significantly increased 81 months after premature loss of a primary maxillary first molar, which suggested that space maintainers were not needed in these cases.

  • twelve month space changes after premature loss of a primary maxillary first molar
    International Journal of Paediatric Dentistry, 2011
    Co-Authors: Yaitin Lin, Wenhsien Lin, Yngtzer J Lin
    Abstract:

    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). 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.

  • immediate and six month space changes after premature loss of a primary maxillary first molar
    Journal of the American Dental Association, 2007
    Co-Authors: Yaitin Lin, Wenhsien Lin, Yngtzer J Lin
    Abstract:

    ABSTRACT 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.

Veronica Giuntini - One of the best experts on this subject based on the ideXlab platform.

  • mesial rotation of upper first molars in class ii division 1 malocclusion in the mixed dentition a controlled blind study
    Progress in Orthodontics, 2011
    Co-Authors: Veronica Giuntini, Tiziano Accetti, Paola Cozza, Efisio Defraia, Lorenzo Franchi
    Abstract:

    Abstract Objective To compare the amount of upper molar rotation in subjects with Class II Division 1 malocclusion and subjects with normal occlusion in the intermediate and late mixed dentition phases. Materials and methods Dental cast measurements were performed in a sample of 120 Class II Division 1 subjects (CL2 group, 67 females and 53 males, mean age 9.4 ± 1.1 years), and in a sample of 58 Class I subjects (CL1 group, 34 females and 24 males, mean age 9.7 ± 1.2 years). Independent sample t tests were used for statistical comparisons (P  Results The amount of upper molar rotation was significantly greater in CL2 group when compared with CL1 group as assessed by both the mesial and buccal molar cusp angles. No differences were found with regard to upper or lower arch depths, or upper Intercanine Width. CL2 group showed a significant deficiency in upper intermolar Width along with a significant posterior transverse interarch discrepancy when compared with CL1 group. Conclusions Subjects with Class II malocclusion in the mixed dentition present with mesial upper molar rotation in about 84% of the cases. The correction of molar rotation may provide between 1 and 2 mm of gain in arch perimeter and of improvement in molar relationships per side in 5 out 6 Class II patients.

Efisio Defraia - One of the best experts on this subject based on the ideXlab platform.

  • mesial rotation of upper first molars in class ii division 1 malocclusion in the mixed dentition a controlled blind study
    Progress in Orthodontics, 2011
    Co-Authors: Veronica Giuntini, Tiziano Accetti, Paola Cozza, Efisio Defraia, Lorenzo Franchi
    Abstract:

    Abstract Objective To compare the amount of upper molar rotation in subjects with Class II Division 1 malocclusion and subjects with normal occlusion in the intermediate and late mixed dentition phases. Materials and methods Dental cast measurements were performed in a sample of 120 Class II Division 1 subjects (CL2 group, 67 females and 53 males, mean age 9.4 ± 1.1 years), and in a sample of 58 Class I subjects (CL1 group, 34 females and 24 males, mean age 9.7 ± 1.2 years). Independent sample t tests were used for statistical comparisons (P  Results The amount of upper molar rotation was significantly greater in CL2 group when compared with CL1 group as assessed by both the mesial and buccal molar cusp angles. No differences were found with regard to upper or lower arch depths, or upper Intercanine Width. CL2 group showed a significant deficiency in upper intermolar Width along with a significant posterior transverse interarch discrepancy when compared with CL1 group. Conclusions Subjects with Class II malocclusion in the mixed dentition present with mesial upper molar rotation in about 84% of the cases. The correction of molar rotation may provide between 1 and 2 mm of gain in arch perimeter and of improvement in molar relationships per side in 5 out 6 Class II patients.

  • dental arch dimensions and tooth wear in two samples of children in the 1950s and 1990s
    British Dental Journal, 2009
    Co-Authors: Matteo Camporesi, Andrea Marinelli, Giulia Baroni, Efisio Defraia
    Abstract:

    Aim The objective of this study was to compare the degree of tooth wear in posterior deciduous teeth and the dental arch dimensions in the mixed dentition in two modern samples living in the same geographic area and separated by almost 35 years. Methods Dental casts of a group of subjects born between 1953 and 1959 were compared with subjects born between 1990 and 1998. The evaluation of tooth wear scores and measurements for posterior and anterior arch segments, intermolar and Intercanine Width, and mesiodistal size of incisors were taken. The available anterior space in both arches and the posterior and anterior transverse dimensions were calculated. Groups were compared using a nonparametric test (Mann-Whitney U-test) for independent samples (P <0.05). Results The results show that both boys and girls of the 1990s showed significantly smaller maxillary intermolar Width when compared with the 1950s. Posterior transverse interarch discrepancy was significantly minor in girls of the 1990s. The comparison of abrasion showed significant differences between the two groups for all examined teeth which appeared to be more abraded in the 1950s group. Conclusions This association can partially explain the greater risk of developing malocclusions in contemporary children compared with children living 35 years before.