Retromolar Pad Research Articles

Relationship of natural occlusal plane with different anatomical landmarks.

To evaluate the parallelism of natural maxillary occlusal plane with inter-pupillary line and ala-tragus line, and to evaluate the anatomic relationship of natural mandibular occlusal plane with retromolar pad among dentate subjects. The cross-sectional study was conducted from September 2017 to February 2018 at Fatima Jinnah Dental College, Karachi, and comprised front and profile photographs of subjects aged 20-28 years while holding the camper's plane against the maxillary occlusal plane. The photographs were imported in a software and an interpupillary line was drawn and the angle with Camper's plane was measured. On both profile pictures, lines were drawn from base of the ala to the superior, middle and inferior points on the tragus. The angle between ala-tragus line and Camper's plane were measured. Intra-orally, height of the mandibular occlusal plane in relation to the retromolar pad was evaluated using a stainless steel scale. Data was analysed using SPSS 23. Of the 109 subjects with a mean age of 23.03±1.36 years, 76(69.72%) were females. Horizontal parallelism of occlusal plane with inter-pupillary line was observed with a mean angle of 1.17±1.27 degrees. The angle between the occlusal plane and the inferior ala-tragus line was 4.25 degrees on the right side, and 4.50 degrees on the left. Intraorally, mandibular occlusal plane coincided with the inferior 48(44%) and the middle third 48(44%) of the retromolar pad. Inter-pupillary line and retromolar pad area should be used as a guide in the determination of plane of occlusion. The ala-tragus line was not found to be a reliable guide.

Clinical characteristics and risk factors of major oral ulcers in the mandibular retromolar region in children.

To describe the characteristics of major aphthous ulcers (MjOU) in children and analyze its potential risk factors. Data were collected from the National Clinical Research Center for Oral Diseases of China between 2012 and 2017. Children younger than 15 years old, who had a giant mucosa ulcer (≥ 1 cm in diameter) and met the diagnostic criteria for MjOU were included in this study. Differences were compared between two subgroups of patients based on the location of the ulcerous lesions. A measurement of ratio (TBR) between the length of the mandibular second molar tooth germ and the height of the mandible was performed in children with MjOU lesions located in the mandibular retromolar pad region (MjOU-P) and their age- and sex-matched controls. A total of 1067 children were diagnosed with oral ulcers during the study period, of which 125 (11.7%, 95% CI: 9.8%-13.7%) met the diagnostic criteria for MjOU. More than half (n = 64, 51.2%) of the MjOU cases were MjOU-P, which had a male predilection (n = 52, 81.3%) with a significant majority at 7 to 9 years of age (n = 43, 67.2%). In comparison to the MjOU located in other regions, MjOU-P lasted longer in duration and had more comorbidities. Logistic regression analysis showed that MjOU-P was statistically significantly associated with TBR controlling age and gender. MjOU-P is a predominant form of MjOU in children and is a distinct subgroup of major ulcers that is likely associated with the development of the mandibular second molars. This study is the first to describe the demographic and clinical features of MjOU in children, which may facilitate the identification and treatment of these patients.

Effect of patient’s age in the occlusal plane determinates by intra-oral landmarks in complete dentures

Aim of the study: This research aims to study the possibility of using the mandibular occlusal plane to determine the maxillary occlusal plane in the complete dentures, and to study the effect of patient's age on the resulting occlusal plane. Materials and Methods: Sample included 40 edentulous patients, ranging in age between 41-84 years (20 male and 20 females). Record bases had anterior occlusal wax rims at the anterior region only in maxillary and mandibular. The mandibular posterior occlusal plane was determined on the master cast at both sides, in line with the convergence of the middle third with the upper third of retromolar pad, and the posterior wax height of mandibular was constructed according to this plane. Then, this plane in patient's mouth was modified to fit the lateral border of the tongue and the commissure of the lips. The determinants of the registration of the centric relationship were fixed to the posterior inferior mandibular occlusal wax rims, and the posterior wax rims of maxillary was made according to the posterior wax rims of mandibular. The relationship of the posterior maxillary occlusal plane to Ala-Tragus line was examined using a double-level ruler specially designed for this purpose. The data obtained was statistically analyzed using Student’s independent T-test, and Pearson correlation coefficients. The level of confidence was set at 95%.Results: The results showed that there were no statistically significant differences in the mean angle values between mandibular occlusal plane and maxillary occlusal plane. There was a statistically significant effect of patient's age on maxillary occlusal plane in females (P=0.010), while there was no statistically significant effect of the patient’s age on maxillary occlusal plane in males and in the whole research sample (P=0.783, 0.064 respectively. Conclusions: The mandibular occlusal plane can be used to determine the maxillary occlusal plane in complete dentures. The use of retromolar pad, the lateral borders of the tongue and the commissure of the lips as intraoral reference points to determine the occlusal plane is a reliable landmark. The impact of patient’s age must be taken into account while determining the occlusal plane in this technique.

ORAL JUNCTIONAL MELANOCYTIC NEVUS ASSOCIATED WITH LENTIGINOUS HYPERPLASIA: A CASE REPORT IN A PEDIATRIC PATIENT

Oral melanocytic nevi (OMNs) are uncommon benign melanocytic proliferations. Clinically, OMNs are small, well-circumscribed, flat lesions, but not uncommonly appear as slightly raised papules. They can be brown, bluish-gray, or almost black, and occasionally non- pigmented. Regarding the OMN etiology and pathogenesis, most studies have focused on its cutaneous counterpart. We present a case of OMN in a pediatric patient. A 4-year-old male was referred presenting a dark macule with regular borders, measuring 6 mm in greater diameter, located on the right retromolar pad, with a time of evolution of 15 days. The clinical diagnoses were melanotic macule and OMN. After excisional biopsy, the microscopic examination revealed junctional melanocytic nevus with lentiginous hyperplasia containing focal melanocytic atypia. After 4 months of follow-up, there is no recurrence or alteration. Thus, lentiginous junctional melanocytic proliferation with focal atypia may be observed in OMN, which should be interpreted with caution, especially in pediatric patients. Oral melanocytic nevi (OMNs) are uncommon benign melanocytic proliferations. Clinically, OMNs are small, well-circumscribed, flat lesions, but not uncommonly appear as slightly raised papules. They can be brown, bluish-gray, or almost black, and occasionally non- pigmented. Regarding the OMN etiology and pathogenesis, most studies have focused on its cutaneous counterpart. We present a case of OMN in a pediatric patient. A 4-year-old male was referred presenting a dark macule with regular borders, measuring 6 mm in greater diameter, located on the right retromolar pad, with a time of evolution of 15 days. The clinical diagnoses were melanotic macule and OMN. After excisional biopsy, the microscopic examination revealed junctional melanocytic nevus with lentiginous hyperplasia containing focal melanocytic atypia. After 4 months of follow-up, there is no recurrence or alteration. Thus, lentiginous junctional melanocytic proliferation with focal atypia may be observed in OMN, which should be interpreted with caution, especially in pediatric patients.

Morphological magnetic resonance imaging study of oral submucosal tissue and buccinator muscle dynamics in the posterior dentition: A clinical study

Statement of problemThe relationship between the buccal mucosa-tongue side wall contact points and at what ratio the submucosal tissue (ST) and buccinator muscle (BUC) change during function are unclear. PurposeThe purpose of this clinical study was to clarify the space and dynamics of the ST and BUC in complete denture wearers by using magnetic resonance imaging and to investigate how denture base shape affects space sealing and the relationship between the ST and BUC. Material and methodsEight edentulous participants wearing maxillary and mandibular complete dentures were enrolled. Wax was added to the buccal border of the dentures, and axial and coronal magnetic resonance imaging scans were made during mandibular rest (MR) to observe the relationship of the buccal mucosa and tongue above the retromolar pads. In addition, on axial images, the thicknesses of the ST and BUC were measured at 3 sites: second molar center, second molar distal (SMD), and retromolar pad center (RPC). Coronal images were made during MR, partial mouth opening, and midmouth opening (MMo). At second molar center, SMD, and RPC, the thicknesses of the ST and BUC were measured at the maxillary buccinator attachment region (point A), the mandibular buccinator attachment region (point B), and the median point between A and B (point M). ResultsDuring MR, contact sealing of the buccal mucosa and tongue on the RPC was noted in 81% of participants. After expanding the denture base with wax, contact was lost in 86% of participants. The ST and BUC thicknesses on the RPC decreased significantly with the addition of wax. During MR, the ST became significantly thicker the further posteriorly it was located. The ST was significantly thicker at point M than at point A for all sections, regardless of mouth opening. The ST and BUC thicknesses in SMD and RPC were significantly thicker at point M than at point B during MR and MMo. The differences of the ST and BUC thicknesses depending on the opening amount were observed only at the point M. In the RPC, the thickness of the ST and BUC decreased significantly as the opening amount increased (ST thickness between MR and partial mouth opening, MR, and MMo: P=.007, P=.001, BUC: P=.018, P=.001, respectively) ConclusionsThe thickness of the ST and BUC differed depending on the site. During mouth opening, these changes in thickness at each site are proportional to the differences in ST and BUC thickness.

Development of a method to clinically identify the position of the lingual nerve relative to the third molar region

ObjectivesTo develop a method to clinically identify the position of the lingual nerve within the lingual tissue in the third molar region by electro-stimulation. MethodsFollowing ethical committee approval a cross-sectional study was performed in 20 healthy participants. A proprietary Electric Pulp Tester (EPT) was used intra-orally to stimulate the lingual nerve and, to identify the vertical position of the lingual nerve, measurements were taken when subjects felt a projected tingling sensation in the tongue as the stimulation probe was placed directly over the nerve. The nerve location was investigated in three positions in relation to the third molar: Point A at the retromolar pad; Point C at the distolingual attached gingivae of the erupted lower second molar and; Point B at the midline of the erupted third molar (or when the third molar was unerupted, midway between Points A & C). ResultsOut of 20 participants 18 (90%) were able to identify the projected tingling sensation on the tongue upon stimulating the nerve, allowing the nerve position to be identified. The mean vertical height of the lingual nerve relative to the third molar was 10.5, 10.75 and 12.5 mm for positions A, B and C respectively. The sensation related to nerve stimulation was well accepted by participants with minimal adverse events. ConclusionWe have demonstrated that stimulation of the lingual nerve with an EPT can clinically identify the position of the lingual nerve in situ. This technique may be useful for the clinical determination of lingual nerve position prior to third molar surgery.

Benign Alveolar Ridge Keratosis: Clinical and Histopathologic Analysis of 167 Cases.

Benign alveolar ridge keratosis (BARK), the intraoral counterpart of cutaneous lichen simplex chronicus, is a reactive hyperkeratosis caused by trauma or friction that presents as a poorly demarcated white papule or plaque on the keratinized mucosa of the retromolar pad or alveolar ridge mucosa (often edentulous). This is a clinical and histopathologic analysis of BARK including evaluation of p53 expression in selected cases. One hundred and sixty-seven cases of BARK were identified from 2016 to 2017 and 112 (67.1%) occurred in males with a median age of 56years (range 15-86). The retromolar pad was affected in 107 (64.1%) cases and the edentulous alveolar mucosa in 60 (35.9%) cases, with 17.4% of the cases presenting bilaterally. BARK showed hyperkeratosis often with wedge-shaped hypergranulosis and occasional focal parakeratosis. The epithelium exhibited acanthosis and surface corrugation with tapered rete ridges often interconnected at the tips. The study for p53 performed in 12 cases showed less than 25% nuclear positivity. BARK is a distinct benign clinicopathologic entity caused by friction, which should be clearly distinguished from true leukoplakia, a potentially malignant disorder.

Oral Fibrolipoma: A Report of Two Cases

Introduction: Lipoma is a benign neoplasm of the fat tissue. Although, lipoma represents as the most common soft tissue neoplasm, lipomas of the oral cavity are very rare. This neoplasm contains 0.1 - 0.5% of all benign tumors of the oral cavity. Case Presentation: We reported two cases of fibrolipomas; the first case was in a 36-year-old female as a swelling in retromolar pad area and the second one in a 71-year-old female as an exophytic mass in pterygomandibular raphe. Conclusions: The novelty of these reported cases of fibrolipomas is that they have been occurred in infrequent area such as retro molar pad area and pterygo mandibular raphe. The lesions were removed by electro cutter with no recurrence at the follow up sessions. Although fibrolipoma is pretty rare in the oral cavity, there are several lesions can also have similar clinical features. Therefore, the histopathological examination is recommended for the clinicians in order to accomplish the final diagnosis.

How to avoid iatrogenic lingual nerve injury in the retromolar area: an anatomical study of retromolar pad and lingual nerve.

This study aimed to investigate the relationship between the retromolar gland and pad, and the relationship between the LN and retromolar gland/pad to establish a new landmark for avoiding LN injury. Sixty-two lingual nerves from fresh-frozen cadavers were used for this study. The age of the specimens at the time of death ranged from 57 to 98 with a mean of 76.5years. The mucous incision was made into the medial border of the retromolar pad and the submucosal tissue depth of the initial incision was bluntly dissected to expose the lingual nerve. When the LN was identified, the mucosa overlying the retromolar pad was removed to expose the retromolar gland to confirm if the retromolar pad corresponds to the retromolar gland. On all sides, the lingual nerve was found to course medial to the retromolar pad and inferior to the inferior border of the superior pharyngeal constrictor muscle to enter the sublingual space via the pterygomandibular space. The retromolar pad corresponded to the retromolar gland on all sides. This demonstrated that the retromolar pad is an overlying mucosa of the retromolar gland. No LN was found to travel through the retromolar gland. We suggest that the retromolar pad can be used as a new landmark for avoiding iatrogenic LN injury.

Determination of Relationship of Maxillary Occlusal Plane with Ala-Tragus Line: A Customised Approach in Aryan and Mongolian Ethnicity.

Background: Determining occlusal plane is challenging and difficult aspect during complete removable partial denture prosthesis rehabilitation. Numerous soft tissue landmarks like commissures of the mouth by Gillis in 1933, parotid papilla by P. F. Foley and G. H. Latta in 1985, height of the retromolar pad, the lateral borders of the tongue etc. had been proposed to assist clinician for determining the occlusal plane. No universally accepted reliable anatomical measurement has been proposed to assist in determining of occlusion plane for different ethnic groups in context to Nepal.
 Material & Methods: This cross-sectional study was conducted in the 60 dentate subjects visiting Nobel Medical College, Nepal, from February 2019 to July 2019. A customized occlusal plane relator was used to evaluate relative parallelism between occlusal plane and alatragal line with respect to different borders of tragus. All the data were collected and statistically analyzed.
 Results: Maxillary occlusal plane was found to be parallel with the line drawn from ala of the nose to the middle of tragus in 66.66%, followed by inferior border of tragus in 18.33% with the least parallelism in superior border of tragus 15%. Relationship of maxillary occlusal plane with alatragal line was not statistically significant among Aryans and Mongolian ethnicity
 Conclusion: This study showed line joining ala of the nose and middle border of tragus is parallel to maxillary occlusal plane. And no difference was found for Aryan & Mongolian ethnicity in relation to alatragal line and maxillary occlusal plane.

Releasing incisions of the buccal periosteum adjacent to the lower molar teeth can injure the facial artery: an anatomical study.

Periosteal releasing incision (PRI) techniques are often used with guided bone regeneration procedures. As complications such as intra- and postoperative bleeding have been noticed, we aimed to study and clarify these as related to the PRI, especially on the mandibular buccal periosteum. Fourteen sides from seven fresh-frozen Caucasian cadaveric heads were used in this study. The seven cadavers were derived from two females and five males. The mean age at the time of death was 75.9 ± 10.8years. The PRI was made using a no. 15c blade using a surgical microscope. Subsequently, the fat tissue lateral to the periosteum was slightly dissected. The diameter of the facial artery (or its branch) and closest relationship between the tooth and position of the artery was recorded. Finally, the artery was traced back proximally to clarify its origin. On all sides, the inferior labial artery (ILA) was identified in the fat tissue lateral to and close to the periosteum. The ILA was closest to the periosteum at the midpoint of the PRI (approximately between the first and second molar teeth area or 10mm mesial to the apex of the retromolar pad). The mean diameter of the ILA was 2.72 ± 0.26mm. This anatomical finding should encourage dentists to make the PRI incision without invading the tissue underneath the periosteum.

Comprehensive understandings in the shape of retromolar pad and its classification based on clinical application

Comprehensive understandings in the shape of retromolar pad and its classification based on clinical application

The effect of build angle on the tissue surface adaptation of maxillary and mandibular complete denture bases manufactured by digital light processing

Statement of problemThe effect of different build angles on the tissue surface adaptation of complete denture bases manufactured by digital light processing (DLP) is unclear. PurposeThe purpose of this in vitro study was to evaluate the effect of build angle on the tissue surface adaptation of DLP-printed complete denture bases. Material and methodsBoth maxillary and mandibular denture bases were virtually designed based on reference casts and fabricated by the DLP technique. For each arch, a total of 40 denture bases were fabricated with 4 different build angle conditions (90, 100, 135, and 150 degrees) and divided into 4 groups (90D, 100D, 135D, and 150D; 10 denture bases per group). The scanned intaglio surface of each DLP denture base was superimposed on the scanned edentulous area of the reference cast to compare the degree of tissue surface adaptation. Root-mean-square estimate, positive average deviation, and negative average deviation values were measured and displayed with a color deviation map. The Mann-Whitney test and Kruskal-Wallis analysis of variance were used for statistical analyses (α=.05). ResultsNo statistically significant differences were found for root-mean-square estimate values among any build angle groups in either the maxillary or mandibular arch. With the increase of build angles, the area of positive deviation in the maxillary arch moved from the palatal region to the posterior palatal seal area, and negative deviation became pronounced at the posterior tuberosity. In the maxillary arch, the 135D group showed favorable color distribution of surface deviation. In the mandibular arch, a positive deviation was detected at the labial slope to the crest of the ridge, whereas a negative deviation was observed at the buccal shelf and the retromolar pad. The 100D group showed favorable distribution of surface deviation in the mandible. ConclusionsIn both arches, the difference of overall tissue surface adaptation was not statistically significant in the 4 different build angles. However, the color deviation map revealed that the 135-degree build angle may be appropriate in the maxillary DLP-printed denture base and the 100-degree angle, in the mandibular denture base.

BENIGN ALVEOLAR RIDGE KERATOSIS: CLINICOPATHOLOGICAL STUDY OF 174 CASES AND P53 EXPRESSION PATTERN

Objectives Benign alveolar ridge keratosis (BARK) is a benign hyperkeratosis that occurs as a poorly demarcated white papule or plaque on the retromolar area or edentulous alveolar ridge mucosa caused by trauma. Histopathologic features are identical to cutaneous lichen simplex chronicus, a condition that results from chronic habitual skin scratching/picking. P53 protein is a tumor suppressor protein that plays a critical role in DNA repair. P53 protein has been shown to be present within 5-25% of the basal cell nuclei in normal oral mucosa and reactive lesions. The objective of this study is to report on the histopathologic features of BARK and to explore P53 expression pattern. Study Design Cases of BARK were identified from the biopsy service of the Harvard School of Dental Medicine from January, 2016 to December, 2017. Randomly selected cases were studied for the presence of P53. Results There were 174 cases comprising 119 males and 55 females (2.2:1; M:F) with a median age of 57 years (range 15-86). The majority were in the sixth (31.0%) and seventh (29.3%) decades. There were 112 (64.4%) cases on the retromolar pad and 62 (35.6%) on the edentulous alveolar mucosa; 27 (15.5%) cases were bilateral. Histopatho-logically, the oral mucosa showed hyperkeratosis often with wedge-shaped hypergranulosis and occasional focal parakeratosis. The epithelium exhibited mild to moderate acanthosis and slight surface undulations or papillomatosis, with tapered rete ridges, often confluent at the tips. The study for P53 performed in 11 cases showed less than 25 % nuclear positivity. Conclusion BARK is a distinct benign clinicopathologic entity caused by friction that is the intraoral counterpart of cutaneous lichen simplex chronicus with which it shares similar histopathologic features. It is not a mere hyperkeratosis which would relegate it to the clinical entity of leukoplakia, and which is a potentially malignant condition.

MULTIFOCAL ORAL MUCOSAL MELANOACANTHOSIS IN A TEENAGER WITH ECZEMA, A CASE REPORT

Introduction Oral melanoacanthosis is a rare, benign, mucosal pigmentation characterized by rapid growth which may clinically resemble mucosal melanoma. A biopsy is often indicated to confirm this diagnosis and exclude other pathologies. A reactive etiology is suggested, as melanoacanthosis typically presents on trauma prone mucosal sites. Melanoacanthosis often occurs as a solitary lesion, however multifocal lesions have been reported. Histopathologic characteristics include pigment-laden, cytologically benign melanocytes with prominent dendritic processes scattered throughout acanthotic stratified squamous epithelium. Regression of the lesion has been observed following biopsy, surgical removal, and spontaneously. Case Description An 18 year old male presented for evaluation of spontaneous, multifocal oral mucosal pigmentation. The patient's medical history was significant for eczema which was refractory to topical steroid therapy. Extraoral examination revealed multiple eczematous lesions of the skin of the face, neck, limbs and focal involvement of lower lip. Intraoral examination revealed dark brown, well defined, flat pigmentation of the maxillary and mandibular attached gingiva, bilateral buccal mucosae, bilateral retromolar pads, soft palate, and focal involvement of the hard palate. A biopsy of the left buccal mucosa demonstrated classic histopathologic features of melanoacanthosis. He was subsequently referred to dermatology for evaluation and management of eczematous skin lesions. The patient's identical twin brother had no evidence of melanoacanthosis and no eczema. Conclusion Melanoacanthosis is a rare pigmented lesion of the oral cavity that often resolves post biopsy. This entity is rarely multifocal. The preferred term melanoacanthosis is used to highlight the reactive, benign nature of the condition.

Mesioangular impacted lower third molars: angulation before and after orthodontic treatment with premolar extraction

Impaction of the lower third molars is due to the lack of space in the retromolar pad. Extraction of premolars in orthodontic treatment helps the uprighting of mesioangular impacted third molars so that they can erupt normally. The aim of this study was to measure changes in angulation during orthodontic treatment of mesioangular impacted lower third molars. This retrospective, cross-sectional analytical study used 25 samples of panoramic radiographs from patients aged 10–21 years before and after orthodontic treatment. Angulation was measured using the long axis of the lower second molars as the reference plane. The Wilcoxon test and paired t-test (p < 0.05) showed no significant changes in lower third molar angulation on both sides (p > 0.05). Radiographs showed a tendency for an increase in angulation, although the change was not statistically significant (p > 0.05). These increases occurred most frequently in the adult group (17–21 years old). It can be concluded that the extraction of premolars in orthodontic treatment did not significantly affect the angulation of impacted third molars.

EVALUATION OF THE RETENTION IN THE THERMOPLASTIC ACETAL RESIN DISTAL EXTENSION PARTIAL DENTURE PROSTHESIS WITH DIFFERENT DENTURE BASE EXTENSIONS

Objectives: The present study was conducted to investigate the retention and the patient satisfaction of the Thermoplastic Acetal resin distal extension partial denture prosthesis with different denture base extension length either extended to covered the retro molar pad or extended just at the anterior border of the retro molar pad in unmodified Kennedy class II mandibular cases. Thermoplastic Acetal resin partial denture is more comfortable and can replace any number of teeth in a dental arch.Methods: Total number of ten healthy patients with unmodified Kennedy class II mandibular cases were selected and received extra coronal attachment on the experimental side , and received unilateral partial denture with thermoplastic Acetal resin framework. The patients were grouped into two groups. Group I received mandibular unilateral distal(without denture base extension) just end at the anterior border of the retro molar padand group II received mandibular unilateral distal(with denture base extension ) covered the retromolar pad. Then the retention evaluation and patient satisfaction was done at insertion of dentures , six months and after 12 month from the insertion.Results: For both groups regarding the retention evaluation, there was insignificant difference between both groups as P-value > 0.05. Regarding the patient satisfaction Group I (without denture base extension) showed statistically significantly higher mean satisfaction score than Group II.Conclusions: The patients were received mandibular unilateral distal(without denture base extension) more satisfied by the prosthesis. and regarding the retention there was non significant difference between both groups so theunilateral partial denture with thermoplastic Acetal resin framework without denture base extension more preferable .

Assessment of Dimensional Disparity in Posterior Arch Width Between Opposing Maxillae and Mandibles in Completely Edentulous Patients with Increased Resorption and Edentulous age - An in vivo Study

Aim: To assess the dimensional disparity in arch width between opposing maxillae and mandibles with edentulous age and increased resorption in edentulous subjects wearing complete denture. Materials and Method: One hundred edentulous subjects wearing complete denture were selected for the study. Maxillary and mandibular casts and a panoramic radiograph were made for each subject. The original height of the mandible before loss of teeth and resorption was predicted by multiplying the distance between the inferior border of the mandible to the lower edge of the mental foramen by a factor of 2.9. The reduction in height of the edentulous mandible was expressed as percentage of the original height of the mandible. The maxillary arch widths immediately anterior to the tuberosities and mandibular arch widths immediately anterior to the retromolar pads were measured. The difference between these two measurements was calculated to determine the discrepancy in posterior arch width. Results: There was no statistically significant difference in the mean values of posterior arch width discrepancy for different groups of edentulous age as well as percentage resorption. The differences in the mean values for amount of resorption with edentulous age were statistically significant. Conclusion: The discrepancy in posterior arch width between opposing maxillae and mandible does not increase progressively with edentulous age and increased reduction in mandibular height. The arch width of the mandible exceeds the arch width of the maxillae in the molar region by an average of 6 to 8 mm after sufficient resorption establishes a definitive alveolar crest. This remains constant regardless of the amount of resorption or edentulous age. The mandibular ridge reduction is found to increase with edentulous age.

Cone-beam computed tomography investigation of crucial mandibular canal variations in Thais

The physiology of the mandibular nerve is an important factor relevant to successful implant planning and surgical procedures in the mandible. Variability among ethnicities may influence the particular safety guidelines for each population. In this study, we retrospectively examined the incidences of canal orientations and variations in Thais using cone-beam computed tomography (CBCT) radiography. CBCT images of 441 mandibular sides of 248 patients aged 20 to 82 years (mean age, 43.7 years) were examined. The incidences of canal courses and variations were assessed by two calibrated observers (Cohen's kappa coefficient >0.8). Descriptive and bivariate statistics were analysed for categorical findings. A p value of <0.05 was considered statistically significant. Two common canal courses were identified: linear curve (Type 1, 39.9%) and elliptic-arc curve (Type 3, 48.1%). In addition, one-fifth of the patients had bifid canals (20.6%). There was a short supplemental canal extending to the second or third molar (Type 2, 53.8%) and a supplemental canal arising in the retromolar pad region (Type 4, 46.2%). An anterior loop was identified in 74.2% of the cases and was frequently bilateral (78.3%). Effective examination of the canal anatomy should be considered prior to surgical procedures because of the shallow curve of the mandibular canal with a high incidence of an anterior loop. In addition, the position of bifid canals was associated with an increased risk of neurovascular alteration in implant placement, sagittal split ramus osteotomy, and retromolar bone harvesting.

Evaluation of Pound concept in determination of mediolateral mandibular posterior teeth position

Background: The ideal teeth arrangement is an important step for success in complete denture fabrication. There are different methods for determining the posterior denture teeth location. The purpose of this study was the comparison of posterior mandibular teeth location in the study group with Pound or Misch theory. Material and methods: An alginate mandibular impression of 80 dentate patients was taken and poured with dental stone. Retromolar pad area, mesial of canine and the lingual cusps of each posterior tooth marked on the cast and then transferred to the graded paper. Distance of each lingual cusp from the internal line of Pound triangle was measured. Data were analyzed with SPSS version 16.0. Result: In the study group, the average distance of lingual mandibular cusp from the internal line of Pound triangle was 1.69 mm in first premolars, 0.94 mm in second premolars, 0.7 mm in first molars and 0.75 mm in second molars. Conclusion: In most cases, distance of lingual mandibular cusps was within 1 mm of Pound triangle. Results were more similar to the Pound rather than the Misch theory.