Molar Angulation Research Articles

Effect of Timing of Third Molar Extraction on the Rate of Mandibular En Masse Distalization Using Buccal Shelf Implants – A Randomized Controlled Trial

This randomized controlled trial evaluates the impact of the timing of third molar extractions on the rate of mandibular en masse distalization and second molar angulation in orthodontic treatment, using buccal shelf implants in borderline Class III malocclusion patients. Late third molar extractions performed less than two weeks before distalization were compared to early extractions, performed six months prior, to investigate the effect of Regional Acceleratory Phenomenon (RAP) on tooth movement. The study also assessed second molar angulation changes, examining distal tipping differences between groups. Results showed a significantly faster rate of distalization in Group II (late extraction) at 0.637 ± 0.098 mm/month, compared to Group I (early extraction) at 0.422 ± 0.075 mm/month. Additionally, Group I experienced significantly greater second molar distal tipping (9.14°) than Group II (3.47°). These findings suggest that the timing of third molar extractions affects both distalization rates and second molar angulation, with early extraction offering a clinical advantage by leveraging RAP and minimizing undesirable tipping.

Anchorage loss of the posterior teeth under different extraction patterns in maxillary and mandibular arches using clear aligner: a finite element study

BackgroundExtracting the premolars is an effective strategy for patients with bimaxillary dentoalveolar protrusion. Clear aligners (CAs) close the extraction spaces through shortening the length of aligners. The contraction force generated by the terminal of aligners makes the posterior teeth tip mesially, which is known as the roller coaster effect. This phenomenon is even worse in the 2nd premolar extraction cases. Posterior anchorage preparation is commonly used to protect the angulation of molars, taking the form of presetting distal tipping value. However, the distal tipping design aggravates the anchorage loss of anterior teeth simultaneously. This study aimed to explore the different anchorage loss of the posterior teeth when the 1st or 2nd premolars were extracted using CAs, respectively in maxillary and mandibular arches, further providing guidance for anchorage preparation design in clinical practice.MethodsTwo bimaxillary finite element models with different extraction patterns were established to simulate the anterior en-masse retraction process of the CAs. In Model 1, the maxillary and mandibular 1st premolars were extracted, while in Model 2, the 2nd premolars were extracted. Finite element analysis methods were utilized to analyze the tipping angle of the anterior and posterior teeth.ResultsCompared between two models, the anterior teeth exhibited a greater lingual inclination tendency and the posterior teeth exhibited a slighter mesial tipping tendency in Model 1 regarding individual tooth. The closer to the extraction spaces, the greater the tip, and the distal tipping tendency of the 1st premolars was more evident than the mesial tipping tendency of the 1st molars in Model 2. Compared between the maxillary and mandibular arches, the mesial tipping tendency of individual posterior tooth was more evident in the maxilla. In addition, the highest hydrostatic stress of the periodontal ligaments was concentrated on the cervical and apical parts directly adjacent to the extraction spaces, and it exhibited relatively uniform distribution in Model 1.ConclusionsThe individual posterior tooth showed the same mesial tipping direction but to different degree when the 1st or the 2nd premolars were extracted during clear aligner treatment. Presetting anchorage preparation design for the posterior teeth is essential to alleviate the roller coaster effect, especially in the 2nd premolar extraction cases. Furthermore, larger anchorage preparation value should be proposed for the maxillary posterior teeth.

Three-Dimensional Evaluation of Impacted Mandibular Third Molar Angulation and its Impact on Lingual Cortical Bone Thickness: A Retrospective Cone-Beam Computed Tomography Study

Background: The removal of impacted lower third molars surgically can cause complications, and the lingual cortical bone thickness in this region becomes a determining factor in the risk of perforation and injury to the lingual nerve (LN). This study was conducted to assess the relationship between different angulations of impacted lower third molars based on Winter’s classification and the thickness of the lingual cortical bone. Variations in lingual cortical bone thickness among the genders were evaluated as well. Methods: Cone-beam computed tomography (CBCT) scans of 50 impacted lower third molar teeth of 50 patients (26 men and 24 women) were evaluated in this study. The lingual bone thickness surrounding impacted lower mandibular teeth was measured at three key points, namely, the cemento-enamel junction of the second mandibular molar, the mid-root of the impacted third molar, and the root apex of the impacted third molar. Mesiodistal angulation and buccolingual angulations of the impacted mandibular third molars underwent investigation. Statistical analysis was conducted using SPSS 23. Data were analyzed using the independent sample t test, one-way ANOVA, multiple linear regression analysis, and Fisher’s exact test. Results: There was a statistically significant relationship between the means of lingual cortical bone thickness surrounding the third molars based on Winter’s classification of third molars impacted at mesiodistal angulation (P=0.00). Regarding gender, buccolingual angulation demonstrated a statistically significant relationship among the means of lingual bone thickness around the third molars (P=0.022). Conclusion: In our study, the thickness of the lingual cortical bone was notably affected in the middle and apical areas of the impacted third molar region. The variable position of the LN near the mandible third molar region was significant in dental procedures due to its proximity. Three-dimensional (3D) imaging CBCT provides preoperative risk assessment that reduces preventable complications that cannot be answered by 2D imaging.

Effectiveness of Clear Aligners on Sequential Maxillary Molar Distalization: Discrepancy between Treatment Goal and Outcome.

Objectives: The purpose of this preliminary study was to determine the differences between planned and actual maxillary molar movements after the completion of treatment with an initial set of clear aligners including sequential maxillary molar distalization. Methods: The data records of 14 non-growing patients who completed orthodontic treatment with sequential maxillary molar distalization using clear aligners were retrospectively evaluated (n= 14, 4 males and 10 females, 33.61 ± 8.57 years). Data on planned tooth movements were obtained from ClinCheck software (ClinCheck Pro version 5.3). The amounts of actual tooth movements were obtained by performing superimposition of lateral cephalograms taken before and after treatment. The amounts of distal translation and tipping between planned and actual maxillary molar movements were compared with the paired Student's t-test. Results: The statistically significant differences between planned and actual translation movements of maxillary first and second molars were shown after completing treatment with the first series of aligners (p < 0.05). The average actual amount of molar distalization on maxillary first molars was less than the planned amount by 1.32 ± 0.42 mm. Similarly, the average actual amount of molar distalization on maxillary second molars was less than the planned amount by 1.57 ± 0.45 mm. The accuracy for molar distalization, namely, the percentage of actual distal translation to planned movement, was 40.11% for maxillary first molars and 35.39% for maxillary second molars. However, the difference between the planned and actual angulation movements was not significant (p > 0.05). Conslusions: In conclusion, the amounts of actual distal translation of maxillary molars through the utilization of clear aligners were significantly lower than planned. However, there were no statistically significant differences between the degrees of actual and planned molar angulation movement.

Tip, torque and rotation of maxillary molars during distalization using Invisalign: a CBCT study

BackgroundDesirable molar distalization by bodily movement is challenging and can be difficult to achieve. This study investigated changes in molar angulation (mesiodistal tipping), molar inclination (buccolingual torque) and rotation during distalization using clear aligner therapy (CAT).Materials and methodsThis retrospective study included 38 cone beam computed tomographic images (CBCTs) taken for patients treated with molar distalization using CAT. The study evaluated pre- (T0) and post-treatment (T1) CBCTs of 19 adult patients (36.68 ± 13.50 years) who underwent maxillary molar distalization using Invisalign® aligners (Align Technology, Inc., San José, CA, USA) with a minimum of 2 mm distalization. Changes in maxillary molar tip, torque and rotation were measured for 61 molars (183 roots). Paired t-test was used to evaluate the differences between pre- and post-treatment readings. The level of significance was set at p ≤ 0.05. The reproducibility of measurements was assessed by the intraclass correlation coefficient (ICC).ResultsMolar angulation did not show significant change after distalization (p = 0.158) however, there was significant increase in buccal molar inclination (p = 0.034) and mesiobuccal molar rotation (p < 0.001).ConclusionMolar distalization of 2 mm did not cause significant molar tipping. Maxillary molars showed significant buccal inclination (increased torque) and mesiobuccal rotation after distalization.

Beyond the ARCH: Examining mandibular third molar movements in response to premolar and single incisor extractions in orthodontic practice

Mandibular third molars have been the interest of the orthodontic professionals, not only because of their Position Eruptive pattern, also because of their possible role in the development of late incisor crowding. The impaction rate of the third molars (mandible &amp;#62; maxilla) is high compared to any other teeth. The impaction incidence of M3s may be lower in patients with orthodontic premolar extraction due to mesial movement of the posterior teeth. In this study angular and positional changes of mandibular 3 molars will be evaluated with premolars as well as single incisor extraction.: This study includes 30 Pre-treatment and post-treatment orthopantomogram (OPG) of patients seeking orthodontic treatment with extractions of premolars, single incisor are categorized into 2 groups -Group I includes premolar extractions, Group II includes single incisor extractions.The study concluded that extracting premolars or single incisors did not result in improved mandibular M3 angulation on both left and right sides during the observation period.The insignificant change in angulation suggests that there are other factors that play a role in the process of alteration of third molar angulation

Three-Dimensional Evaluation of Treatment Effects and Post-Treatment Stability of Maxillary Molar Intrusion Using Temporary Anchorage Devices in Open Bite Malocclusion.

Background: We investigated treatment outcomes and post-treatment stability in 10 patients with an anterior open bite and nonsurgical orthodontics. Methods: The patients underwent maxillary molar intrusion using temporary anchorage devices (TADs) to deepen the overbite due to mandibular autorotation. Lateral cephalograms and dental cast models were obtained before treatment (T0), immediately after it (T1), and >1 year after it (T2). Skeletal and dental cephalometric changes and three-dimensional movements of the maxillary dentitions were evaluated. Results: At T0, cephalometric analysis indicated that patients had skeletal class I with tendencies for a class II jaw relationship and a skeletal open bite. During active treatment (T0 to T1), the maxillary first molar intruded by 1.6 mm, the mandibular first molar extruded by 0.3 mm, the Frankfort-mandibular plane angle decreased by 1.1°, and the overbite increased by 4.1 mm. Statistically significant changes were observed in the amount of vertical movement of the maxillary first molar, Frankfort-mandibular plane angle, and overbite. Three-dimensional (3D) dental cast analysis revealed that the maxillary first and second molars intruded, whereas the anterior teeth extruded, with the second premolar as an infection point. In addition, the maxillary molar was tipped distally by 2.9° and rotated distally by 0.91°. Statistically significant changes were observed in the amount of vertical movement of the central incisor, lateral incisor, canine and first molar, and molar angulation. From T1 to T2, no significant changes in cephalometric measurements or the 3D position of the maxillary dentition were observed. The maxillary and mandibular dentitions did not significantly change during post-treatment follow-up. Conclusions: Maxillary molar intrusion using mini-screws is an effective treatment for open bite correction, with the achieved occlusion demonstrating 3D stability at least 1 year after treatment.

Comparison of two methods in maxillary canine retraction

The aim of this prospective clinical study is to evaluate the effects of laceback and Uprighter techniques on maxillary canine retraction using digital models and panoramic radiographs and to compare the results.Sixteen patients (10 females, 6 males) with an average chronological age of 16.24±2.99 years, requiring fixed orthodontic treatment with upper canines located in a high vestibular position and the need for bilateral first premolar extraction, were included in this study. 0.018-inch Roth brackets were used in the patients. In this split-mouth design study, while laceback was used on one side, Uprighter was used on the other side. Tooth movements were measured on three-dimensional models and panoramic radiographs obtained at the beginning of treatment (T0), 2 months later (T1), and 3.5 months later (T2). Two-way analysis of variance was applied for the comparison of differences between the groups in repeated measurements.The difference between groups was found to be statistically significant in terms of canine distalization, canine rotation, and molar angulation amounts. There was no statistically significant difference in the other parameters.Both uprighter and laceback techniques can be applied in maxillary canine cases located in the high vestibule. When Uprighter is used, the canine is distalized much more. However, it should be noted that while more molar tipping may occur when laceback is used, more canine distopalatal rotation may occur when uprighter is used.

Prevalence of Lower Third Molar Angulations in Duhok Province of Kurdistan Region- Iraq

Prevalence of Lower Third Molar Angulations in Duhok Province of Kurdistan Region- Iraq

Prevalence of Impacted Third Molars Among Iraqi Patients Attending Al-Maghrib Specialized Dental Health Center in Relation to Age and Gender Using Panoramic Radiographs

Introduction: The most commonly impacted tooth is third molar. Aim: To investigate the prevalence of pattern of third molar impaction among patients attending Al-Maghrib specialized dental health center in Baghdad city. Materials and Methods: A cross-sectional analysis was conducted on digital orthopantomogram (OPGs) of high quality belonged to 519 patients referred to Al-Maghrib specialized dental health center in Baghdad city/Iraq between January2023 to June 2023. Data include age, gender and angulation type. Results: The age range was 20-70 years old. The prevalence of impacted third molar was 92%. The percentage of impacted lower third molar (51%) was higher than that of upper third molar (49%). Middle-aged patients (20-30, 31-40 years) recorded higher percentages of impaction than other age groups (31.7% and 32% respectively). Male gender revealed higher percentage (58%) of impaction than female gender (42%). Vertical and then mesioangular inclinations are the most prevalent types of lower third molar angulations (45% and 30% respectively). Conclusion: Higher prevalence of impaction in third molars was recorded in the current study that was more prevalent in the middle-aged patients with male predilection. The impaction was more common in the mandible than the maxilla. The most prevalent lower third molar angulation is vertical followed by mesioangular.

Evaluation of the effect of extraction in comparison to distalization on the maxillary third molars in class II malocclusion: a retrospective study

ObjectiveTo compare the effects of first premolar extraction versus distalization on the vertical position and mesiodistal angulation of maxillary third molars (MxM3) in adolescent class II patients.MethodsThe panoramic x-rays (OPGs) of 200 adolescent class II patients with developing MxM3s were screened. The chosen sample consisted of 2 groups: Group 1 (Distalization) comprising 48 MxM3s, and Group 2 (Extraction) comprising 50 MxM3s. The pre- and post-treatment OPGs were traced to detect the mesiodistal angulation changes of the second molars (MxM2) and MxM3s.ResultsThe angulation and vertical position of the MxM3s at T0 & T1 were also evaluated using Archer’s classification. The distalization group presented a non-significant decrease in the mean angulation of MxM2 and MxM3 (-2.4o & -4.5o uprighting respectively). In the extraction group, both MxM2 and MxM3 presented a highly significant decrease in the mean angulation (-10.5o & -11o uprighting respectively). The angulation and vertical position change of MxM3 significantly improved in the extraction group when compared to the distalization group (P < .001).ConclusionSignificant uprighting and occlusal positioning of the maxillary third molars occurred in the premolar extraction treatment group when compared to the distalization treatment group. The results of the current study highlight the importance of recognizing maxillary third molars during orthodontic treatment planning of Class II malocclusion cases.

Third Molar Comparison in Class I and II Extraction and Non-extraction Orthodontic Treatment: A Retrospective Longitudinal Study.

This study compared third molar angulation and eruption status in Class I and II malocclusions after orthodontic treatment with and without first premolar extractions. The sample comprised 93 patients divided into four groups: Group 1, Class I malocclusion treated with first premolar extractions; Group 2, Class I malocclusion treated without extractions; Group 3, Class II malocclusion treated with first premolar extractions; and Group 4, Class II malocclusion treated without extractions. Panoramic radiographs were used to evaluate the third molar mesiodistal angulations at T1 (pretreatment), T2 (posttreatment), and T3 (long-term posttreatment). Third molar eruption status was assessed in dental casts. Intergroup angulations and eruption status comparisons were performed using one-way analysis of variance (ANOVA), followed by Tukey's test and Kruskal-Wallis test, respectively. Significantly greater mesial angulation and percentage of erupted right maxillary third molars were observed in the Class I extraction group. Significantly greater eruption status of the right mandibular third molars was observed in the Class I and Class II malocclusion extraction groups. Class I and II malocclusion extraction treatment exhibited more favorable angulations and a greater number of erupted third molars than non-extraction treatment. The non-extraction groups exhibited a greater percentage of unerupted third molars.

Third molar angulation and retromolar space after functional orthodontic treatment : Evaluation of panoramic radiographs after monoblock or Herbst appliance.

The aim of this respectively cohort study was to evaluate the lower second and third molars and canine angulations, retromolar space and occlusal relationships after functional orthodontic treatments with the monoblock or Herbst appliance using panoramic radiographs. Pre- and posttreatment cephalometric and panoramic radiographs of 133 patients (mean age 13.89 ± 1.14years) treated non-extraction with monoblock (n: 44), Herbst (n: 45) and fixed orthodontic appliances (control group; n: 44) were included to the study. Dental and skeletal measurements were performed on cephalometric radiographs. The angle between the third and second molars, and canines with the lower border of the mandible and the occlusal plane, gonial angle, the angle between the third and second molars and the retromolar space width were assessed on pre- and posttreatment panoramic radiographs. Paired and independent ttests were used for the statistical analysis of the data for intragroup and intergroup comparisons. Functional treatment with both the monoblock and the Herbst appliances resulted in improvement of skeletal classII relationships. Retromolar space significantly increased in the functional appliance groups compared to the control group (p ≤ 0.001), but improvement of the angulations of posterior teeth was significant only in the monoblock group (p ≤ 0.001). While both the Herbst and monoblock appliances led to an increase in retromolar space, monoblock treatment resulted in more favorable angulation of the third molars compared to the Herbst treatment.

Distribution and impaction patterns of third molars in a sample of German population: Retrospective analysis in a high turnover maxillofacial department

BackgroundThe surgical removal of impacted third molars is considered a routine procedure for oral and maxillofacial surgeons. However, the distribution of impacted molars varies among different populations. A study into impaction patterns in the German population is currently not described. The aim of this retrospective study is to determine patterns of impacted third molars in a sample of German population, to identify gender and age specific differences as well as further risk factors for impacted molar extraction and to compare these results with other studies. Materials and methodsThe clinical findings and digital panoramic radiographs of 84 patients with a total of 243 impacted third molars that had been subjected for tooth extraction, from January to September 2023, were collected and analyzed. All third molars were analyzed according to Winter´s angulation, Pell and Gregory Score of depth and relationship to ramus. Furthermore, inferior alveolar nerve and maxillary sinus proximity were identified through a newly developed risk score and an analysis of patient´s gender and age regarding impaction patterns was performed. ResultsNo significant gender specific differences were found regarding the impaction patterns. Third molar angulations significantly differed regarding patient´s age (cut-off 26 years). In comparison, third molar depth, bone coverage, nerve approximity and angulation patterns differed from the results of other populations. ConclusionThe results of this study can serve as a baseline for further studies of third molar impactions in the German population to minimize perioperative complications in impacted third molar surgery.

Correlation of mandibular third molar orientation and available retromolar space with arch length discrepancy in subjects with different growth pattern.

To evaluate, compare, and correlate the mandibular third molar orientation and available retromolar space with arch length discrepancy in subjects with skeletal class II malocclusion and different growth pattern. A total of 250 patients (age >18 yrs) having skeletal class II malocclusion (based on YEN angle and WITS appraisal) were divided into two groups. Both the groups (Group I with erupted mandibular third molars {N = 150} and Group II with impacted mandibular third molars {N = 100}) were subdivided into subgroups IA (n = 71), IB (n = 19), IC (n = 71) and Group IIA (n = 54), IIB (n = 30) and IIC (n = 16) for normo-, hypo- and hyperdivergent growth patterns, respectively (based on Jarabak ratio and Sn-Go-Gn angle). Four parameters, that is, retromolar space, width of third molar, third molar angulation, and mandibular incisor angulation were measured on orthopantomogram whereas arch length discrepancy was calculated with the help of lateral cephalogram and study model. Intragroup, intergroup comparisons (using unpaired Student's 't' test), and Pearson's correlation coefficient for assessed parameters were obtained. Third molar angulation and retromolar space were significantly higher in Group I than in Group II (hyperdivergent pattern of Group II had highest value). The width of third molar was less than retromolar space in Group II and vice versa for Group I. Mandibular incisor angulation and arch length discrepancy were more in Group II than in Group I, but difference was statistically nonsignificant. Strong positive correlation was observed for mandibular third molar angulation and available retromolar space in normo- and hyperdivergent growth patterns. Lack of retromolar space along with increased amount of arch length discrepancy and mandibular incisor angulation is responsible for increased chances of third molar impaction in some subjects with class II malocclusion.

Risk determination of inferior alveolar nerve injury after mandibular third molar extraction

Introduction. Extraction of impacted molars may be accompanied by complications, including inferior alveolar nerve (IAN) injury, with an incidence of up to 8.4% [3]. Among the risk factors for IAN trauma is the relationship between the molar and the mandibular canal (MC). The aim of the study is to evaluate the difficulty of extraction of impacted M3M and the risk of NAI injury based on radiological clichés. Materials and methods. A retrospective descriptive study was performed, including 25 molars. OPGs, and CBCTs of the patients were evaluated. Age, sex of patients; degree of inclusion according to Pell &amp; Gregory; angulation of molars; Rood &amp; Shehab signs were studied. Results. According to the degree of difficulty of the intervention, we obtained: low difficulty — 2 cases; medium — 21 cases; high — 2 cases. 84% of cases showed an association between more than one signs proposed by Rood &amp; Shehab. The most common were loss of white line (33%), followed by MC narrowing and root darkening (22% each). The incidence of NAI injury was 8.3%. Conclusions. Risk prediction is useful in planning and facilitates decision making regarding the extraction technique of the impacted M3M.

Skeletal and Dentoalveolar Changes in Growing Patients Treated with Rapid Maxillary Expansion Measured in 3D Cone-Beam Computed Tomography.

The skeletal and dental effects of rapid maxillary expansion (RME) have been extensively studied, but high-quality research is still needed to determine the three-dimensional (3D) effects of RME. The aim of this study was to compare skeletal and dentoalveolar parameters through cone-beam computed tomography (CBCT) pre- (T1) and post-treatment (T2) with respect to RME. Twenty growing patients (mean age 10.7 years) were treated with a Hyrax-type expander. A 3D CBCT was performed at T1 and T2, measuring nasal width, maxillary width, palatal height, maxillary arch perimeter, angulation of the upper first molar, and intermolar width. The mean palatal suture opening was 2.85 ± 0.62 mm (p < 0.0001). Nasal width increased 1.28 ± 0.64 mm and maxillary width 2.79 ± 1.48 mm (p < 0.0001). In contrast, palatal height was reduced 0.65 ± 0.64 mm (p < 0.0001). Regarding arch perimeter, the radicular perimeter increased 2.89 ± 1.80 mm, while the coronal perimeter increased 3.42 ± 2.09 mm (p < 0.0001). Molar angulation increased 5.62 ± 3.20° for the right molar and 4.74 ± 2.22° for the left molar (p < 0.0001). Intermolar width increased 5.21 ± 1.55 mm (p < 0.0001). Treatment with Hyrax produced a significant opening in the mean palatal suture. Also, a significant increase in nasal width, maxillary width, arch perimeter, molar angulation, and intermolar width, and a decrease in palatal height, were observed.

The Clinical and Radiological Evaluation of Impacted Third Molar Position, Crown and Root Morphology.

This study aimed to analyze the crown and root morphology of maxillary and mandibular third molars, and assess their position in relation to adjacent anatomical structures using clinical examination and radiographic images. A total of 176 extracted impacted or partially impacted third molars were included in this study. Orthopantomogram images (OPG) were used to evaluate the number of roots, position, depth of impaction relative to the occlusal plane of the second molar, and angulation of maxillary and mandibular third molars. The extracted teeth were examined to determine the actual number of roots. The root morphology was classified using the Alavi classification system for maxillary third molars and the Machado classification for mandibular third molars. Additionally, the number of cusps, crown dimensions, and morphology were analyzed using digital and dental calipers. The extracted samples exhibited a significantly higher number of roots compared to the number assessed on OPG images (P<0.001). The majority of mandibular third molars had two fused roots (37.39%) and a five-cuspid crown (48.70%), while maxillary third molars had three fused roots (26.23%) and four cusps (42.62%). Both maxillary (60.66%) and mandibular third molars (61.74%) were predominantly vertically positioned. Regarding the depth of impaction, maxillary third molars were primarily classified as Class C (65.57%), while mandibular third molars were classified as Class B (47.83%). Differences in crown shape were observed, with maxillary crowns being mostly triangular (36.07%) and mandibular crowns being oval (38.26%). Maxillary third molars had shorter crowns compared to mandibular third molars (P<0.05). The root morphology of maxillary and mandibular third molars in the population of Bosnia and Herzegovina displays variability. Orthopantomogram imaging was found to be inadequate for accurate determination of the number of roots in third molars. The number of cusps on third molars cannot be relied upon as a predictor of the number of roots. The study's findings will have implications for dental practice, particularly for oral surgeons and restorative dentists.

Skeletal and Dentoalveolar Changes With Mandibular Expansion in Growing Children.

Introduction The primary objective of this study was to quantitatively analyze the skeletal and dentoalveolar parameters following the mandibular expansion with a banded appliance. It was also part of the study to evaluate the amount of dental expansion and assess the change in the intermolar and individual first molar angulation. The basal bone parameters were compared to assess the skeletal effect of removable mandibular expansion appliance therapy. Methods In this retrospective cone beam computed tomography (CBCT) study, a total of 80 subjects with mandibular expansion therapy were screened. After imposing inclusion/exclusion criteria, 70 patients (40 females and 30 males) with a mean age of 8.8±1.24 years and 4.79±3.59 months were included. The mean expansion period was 3.04±1.61 months. Skeletal parameters such as buccal cortical thickness, buccal bone width, and cortical density were measured at 2mm from the alveolar crest, mid-root, and apex region in the coronal slice at the level of the mesiobuccal root of the first molar. Expansion parameters such as intermolar width, intermolar angulation, and individual molar angulation were also measured in the same slice. Finally, basal bone parameters such as inter-mental foramina distance and anterior arch perimeter were recorded. Results No significant difference (p>0.05) was found for most skeletal parameters following the expansion, except for the mid-root buccal bone width (p<0.05). On average, 4.54±2.53 mm of dental expansion (p<0.05) was achieved at the first molar region. Individual molar angulation showed a statistically significant difference (right = 7.46±7.91°, left = 7.53±7.18°, p=<0.05). The basal bone parameters showed no significant difference (p>0.05). Conclusions The mandibular expansion device leads to an increase in intermolar distance. The amount of expansion achieved with such devices is due to the buccal tipping of the molars. Skeletal effects such as cortical thickness, buccal bone width, or changes in the basal bone dimensions should not be expected with mandibular expansion therapy.

Radiographic Evaluation of Impacted Third Mandibular Molar According to the Classification of Winter, Pell and Gregory in a Sample of Cameroonian Population.

The extraction of impacted third molars (M3) is a common surgical procedure in dentistry and oral surgery. Various complications, including inferior alveolar nerve (IAN) damage, may occur during and after extraction of this tooth. Radiographic examination should provide information about the M3 itself, but also about the surrounding bony structure and the relationship of the roots to the IAN and the adjacent second molar, which is often traumatized during this extraction. The aim of our study was to evaluate the depth and angulation of impacted mandibular third molars (M3) from panoramic radiographs, according to the classifications proposed by Winter and Pell & Gregory. Radiographic signs present on the orthopantomogram showing M3 depth, and retromandibular available space according to the Pell & Gregory classification were evaluated. Evaluation of the M3 angulation relative to the M2 according to Winter's classification was also done. Student's t test was used to determine the association between side or sex and different variables. The depth of impaction of the M3 crown was level A accounting for 54.4% (n=260) of the PR while level B constituted 35.7% (n=171) of the images. Regarding the availability of retromandibular space, Class I constituted 36.8% (n=176). The Class II accounted for 55.9% (n=267) of PR. Our study showed that 54.4% of M3 were located at the same level as the occlusal plane of the second molar, while in 56% of PR the space between the second molar and the ramus of the mandible is less than the mesiodistal diameter of the third molar. This research showed that 23.1% of M3 had a level of vertical angulation, a level that allows for less painful luxation of the impacted molars. These results seem to show a relatively high level of difficulty in mobilizing and extracting M3 from Cameroonian patients.