Analysis of Relative Parallelism Between Hamular-Incisive-Papilla Plane and Campers Plane in Edentulous Subjects: A Comparative Study

The study was undertaken to evaluate the parallelism between hamular-incisive-papilla plane (HIP) and the Campers plane. And to determine which part of the posterior reference of the tragus i.e., the superior, middle or the inferior of the Camper’s plane is parallel to HIP using digital lateral cephalograms. Fifty edentulous subjects with well formed ridges were selected for the study. The master casts were obtained using the standard selective pressure impression procedure. On the deepest point of the hamular notches and the centre of the incisive papilla stainless steel spherical bearings were glued to the cast at the marked points. The study templates were fabricated with autopolymerizing acrylic resin. The subjects were prepared for the lateral cephalograms. Stainless steel spherical bearings were adhered to the superior, middle, inferior points of the tragus of the ear and inferior border of the ala of the nose using surgical adhesive tape. The subjects with study templates were subjected to lateral cephalograms. Cephalometric tracings were done using Autocad 2010 software. Lines were drawn connecting the incisive papilla and hamular notch and the stainless steel spherical bearings placed on the superior, middle and inferior points on the tragus and the ala of the nose i.e., the Campers line S, Campers line M, Campers line I. The angles between the three Camper’s line and the HIP were measured and recorded. Higher mean angulation was recorded in Campers line S –HIP (8.03) followed by Campers line M-HIP (4.60). Campers line I-HIP recorded the least angulation (3.80). The HIP is parallel to the Camper’s plane. The Camper’s plane formed with the posterior reference point as inferior point of the tragus is relatively parallel to the HIP.     

Three-dimensional analysis of the occlusal plane related to the hamular-incisive-papilla occlusal plane in young adults

The planes which serve as references for cranium and face in dental clinical application included the occlusal plane, Frankfort plane, Camper's plane and hamular-incisive-papilla (HIP) plane. The HIP occlusal plane is a horizontal plane passing through the bilateral hamular notches and the incisive papilla (Dent Surv. 1975;51:60). The aim of this study was to estimate the relationship between the various occlusal planes and the HIP plane in Taiwanese young adults with approximately optimal occlusion. Study casts of 100 young adults (50 men and 50 women) were selected in this study. All market points on the maxillary casts were measured by a three-dimensional precise measuring device. The angular relationship between the four various occlusal planes and the HIP plane were investigated. The vertical distances between the cusp tips and incisal edges of maxillary teeth to the HIP plane were measured. Data were performed by the Statistic analysis software programme (JMP 4.02). The Student's t-test and Pearson's correlation test were used to test the statistical significance (P < 0.05). The results showed that the occlusal plane defined as the incisal edge of maxillary central incisor to mesiobuccal cusp tips of maxillary second molars had the smallest included angle with the HIP plane (2.61 +/- 0.81 degrees). The incisal edge of maxillary right central incisal to mesiopalatal cusp tips of maxillary first molars had the largest included angle with the HIP plane (7.72 +/- 1.60 degrees). The curve is drawn through the buccal cusp tips of maxillary teeth had better parallelism with the HIP plane.     

Relationship of maxillary incisors in complete dentures to the incisive papilla

We investigated the relationship of the maxillary central incisors to the incisive papilla in wearers of complete dentures. First, image analyzer software was used to examine the relationship of the midpoint of the incisive papilla to the labial surface of the maxillary central incisors on occlusal photographs of 120 maxillary casts from dentate Malaysian adults. Then, an Alma denture gauge was used to identify the position of the labial surface of the maxillary central incisors in relation to the midpoint of the incisive papilla in complete dentures from 51 patients who requested replacement dentures at the Faculty of Dentistry, University of Malaya. The mean incisor distance to the incisive papilla in dentate adults was 9.59 ± 1.00 mm, while the mean incisor distance to the incisive papilla in complete dentures was 6.34 ± 1.87 mm. Thus, in our sample of edentulous patients, the anterior teeth in complete dentures were positioned approximately 3 mm closer to the incisive papilla, as compared with the position of the central incisors in natural dentition, and did not duplicate the position of the natural anterior teeth.     

The Incisive Papilla: A Significant Landmark in Prosthodontics

Several investigators have studied the horizontal relationship between incisive papilla and maxillary central incisor and measured the papilla incisor distance in dentate subjects to extrapolate this distance as a guide to place maxillary central incisors in complete dentures. Based on this premise, incisive papilla is recognized as an important landmark in complete denture construction. Papilla incisor measurements were made either from the middle or posterior border of the papilla and certain ethnic and national norms have been recommended to set the central incisors in complete dentures. This study was done on Dravidian dentate subjects to relate incisive papilla to central incisors and canines and also to ascertain its shape. During its transition to the edentulous state, incisive papilla changes its shape consequent to remodeling of the alveolar bone, palatal mucosa and interdental papilla following extraction of central incisor teeth. It was found that the papilla in dentate is not always round but seen in several forms. In some it was a double papilla and in a few it was rudimentary. The center of the papilla also changes from its dentulous to edentulous state. The posterior border is a relatively stable landmark since it undergoes least change after extraction of anterior teeth.     

Relationship of the maxillary canines to the incisive papilla

The positioning of denture teeth in a completely edentulous patient is dependent on many factors. Anatomic landmarks are frequently valuable in complete denture fabrication. The topography of the palatal soft tissue in relationship to tooth position in dentate patients may be an aid in the placement of denture teeth. By using casts formed from irreversible hydrocolloid impressions, 50 subjects were examined to determine the orthographic distance from the posterior of the incisive papilla to a line intersecting the distal contact points of the maxillary canines. In 92% of subjects the posterior point of the incisive papilla was approximately 3 mm anterior to the line between the distal points of the canines. Neither gender, age, nor maxillary tooth arch form affected this distance.     

Position of teeth on the edentulous atrophic maxilla

For prosthetic treatment of strongly atrophic alveolar wall, some biometric methods have been developed. The measurements taken from plaster cast models of 230 edentulous, average 29.9 years, and 125 dentulous post-menopausal women were correlated. In the edentulous maxilla the sagittal position of canine teeth can be determined by the oral edge of incisive papilla. The transverse position of canine teeth was on the outer edge of the alveolar wall because of the extensive loss of buccal alveolar bone. On the incisor area the facial surfaces of the central incisors were determined by the oral edge of incisive papilla and the distance was about twice the length of the papilla. The sagittal position of the first premolars was one-third and the first molars two-thirds the length of the palate from the plane of the labial edge of incisive papilla. The transverse position of the premolars and molars was determined by the scar-line, which is a cord-like elevation or track on the alveolar mucosa after extractions of the teeth. According to the comparative method, the position of the scar-line differed from the lingual gingival margin line and was situated about half breadth of the tooth in a buccal direction from it. The transverse position of premolar and molar in the edentulous maxilla is about the middle of the scar-line in a facio-buccal direction. In the setting of the artificial teeth, the facial surfaces of these teeth should be on average 5.0-6.0 mm sideways from the scar-line, whilst the total bilateral breadth of the alveolar wall in the sulcus area was on average 1.0-2.0 mm larger.     

The Position of the Occlusal Plane in Natural and Artificial Dentitions as Related to Other Craniofacial Planes

Purpose: This study aimed at determining the most reliable ala‐tragus line as a guide for the orientation of the occlusal plane in complete denture patients by use of cephalometric landmarks on dentate volunteers. Materials and Methods: Analysis was made for prosthodontically related craniofacial reference lines and angles of lateral cephalometric radiographs taken for 47 dentate adults. Variables were determined and data were analyzed using SPSS (SPSS, Inc., Chicago, IL). Results: Occlusal plane angle formed between the occlusal plane and Camper's plane had the lowest mean value in the angle formed with Camper's I, which represents the measure taken from the superior border of the tragus of the ear with a score of 2.1°. The highest was measured in the angle formed with Camper's III with a score of 6.1°, while the angle formed with Camper's II was 3.2°. The differences between the three planes in relation to the occlusal plane was significant (p < 0.001). Conclusion: The superior border of the tragus with the inferior border of the ala of the nose was most accurate in orienting the occlusal plane.     

Using cone beam computed tomography to determine safe regions for implant placement

This study sought to identify and follow the course of the incisive canal in the mental interforaminal region of the human mandible and to describe other anatomical landmarks present in this region. Cone beam computerized tomography (CBCT) studies for 40 patients were collected from the database at the Department of Oral & Maxillofacial Radiology, School of Dentistry, Lebanese University. Ten patients had edentulous mandibles; the other 30 had partially or completely dentate mandibles. Axial native images and panoramic and cross-sectional reconstructions were examined to assess the anatomical landmarks in the anterior mandible. Multiple neurovascular canals and foramina were clearly detected on CBCT studies of the mandible. Numerous foramina were seen on the internal surface of the mandible, even distant from the midline. The incisive canal was identified in 97.5% of the images. These anatomical landmarks should be evaluated carefully during preoperative planning.     

Bone Mineral Density in Periodontally Healthy and Edentulous Postmenopausal Women

Osteoporosis is the most common metabolic disease among postmenopausal women. Reduced masticatory function caused by tooth loss may be a contributing risk factor of osteoporosis. The present study examined the effect of dentate state on skeletal bone mineral density (BMD) in postmenopausal women. Fourteen periodontally healthy dentate subjects (group H; mean age: 64.0 ± 5.5 years) and 12 edentulous subjects (group E; mean age: 67.1 ± 2.9 years) were randomly selected from the clinics of the departments of Periodontology and Gerodontology, respectively. Informed consent was obtained from all participants. BMD of the lumbar spine (L2-L4) was measured by dual energy x-ray absorptiometry. In addition, occlusal force was measured in 11 group H subjects and 8 group E subjects by using an occlusal diagnostic system. Risk factors associated with osteoporosis including age, calcium intake, physical activity, and cigarette smoking and causes of tooth loss were assessed by interview and questionnaire sent to all participants. The BMD of group H was 1.07 ± 0.21 g/cm² and that of group E was 0.89 ± 0.17 g/cm², which was significantly different (P < 0.05). The occlusal force of group H and E patients was 312.4 ± 148 N and 56.3 ± 36 N, respectively, which was significantly different (P < 0.05). Risk factors such as calcium intake, physical activity, and smoking did not differ significantly between the 2 groups. Thus, the periodontally healthy dentate women, who showed about 6 times higher occlusal force than edentulous women, maintained significantly higher BMD of the lumbar spine than edentulous women. Our results suggest that sufficient masticatory function with periodontally healthy dentition may inhibit or delay the progress of osteoporotic change in skeletal bone or that edentulous women may be more susceptible to osteoporosis. Ann Periodontol 1998;3:322–326.     

全口义齿(牙合)平面倾斜角度对支持组织受力的影响

目的：研究全口义齿不同倾斜角度的He平面对无牙颌支持组织受力的影响。方法：以标准的无牙颌模型为原形建立无牙颌及全口义齿的有限元模型,运用三维有限元应力分析方法对其进行应力及位移分析。结果：得出了七种模型的基托及无牙颌骨的位移及应力分布值。结论：He平面与牙槽嵴顶不平行时,对支持组织的应力分布有明显影响。     

全口义齿基托边缘位置及形态的临床研究

目的：分析义齿基托边缘实际位置和形态以及与上下颌解剖标志的关系。方法：按照规范化标准制取功能性印模,为10名无牙颌患者进行全口义齿修复。在义齿试戴前后及义齿使用合适后,测量基托边缘厚度,记录基托边缘调改量,观察基托边缘和上下颌解剖标志的关系。结果：全口义齿基托边缘在翼上颌切迹区、颊棚区、远中颊角区、舌骨嵴区的调改量大,具有统计学意义（P ＜0．05）。下颌义齿颊侧基托边缘在颊棚区与外斜嵴平齐,在远中颊角区避让咬肌附丽。舌侧基托边缘在下颌隆突区与下颌隆突平齐。结论：全口义齿基托边缘在翼上颌切迹区、颊棚区、远中颊角区、及舌骨嵴区易过度伸展。     

Occlusal Plane Location in Edentulous Patients: A Review

Occlusal plane orientation is an important factor in the construction of a complete denture. Occlusal plane could be oriented using landmarks in the mandibular arch as well as in the maxillary arch. In the mandibular arch there are few landmarks which could be used to orient the occlusal plane like the retromolar pad, corner of the lips (lower lip length) whereas the maxillary arch has a number of landmarks, of which the ala-tragal line is the most commonly used and the same being the most controversial. In the following article different landmarks and its accuracy for orientating the occlusal plane in an edentulous subject as studied by various authors has been discussed.     

Evaluation of maxillary incisive canal characteristics related to dental implant treatment with computerized tomography: a clinical multicenter study

Background: A close anatomic relationship between the incisive canal and the roots of the central maxillary incisors should be kept in mind during dental‐implant treatment in the anterior maxilla. The aim of the present study is to analyze incisive canal characteristics on computed tomography (CT) sections and to evaluate its relation to bone anterior to the canal with regard to dental implantation. Methods: A total of 933 partially edentulous and/or edentulous patients scheduled for implant insertion in four dental clinics enrolled in the present study. The following were measured and recorded from CT sections for analysis: 1) diameter and length of the incisive canal; 2) width and length of the bone anterior to the canal; 3) palatal bone width and length; and 4) root width and length of the central incisor. Results: Mean canal length was 10.86 ± 2.67 mm, and mean diameter was 2.59 ± 0.91 mm. Canal length was shortened in edentulous anterior maxilla compared to dentate maxilla. However, canal diameter did not show any difference between dentate and edentulous groups. Males had a longer and wider incisive canal than females. Canal shape was mostly cylindrical in 40.73% of images. No correlation was found with mean canal length and mean canal diameter according to age. Conclusions: Although variations exist in every patient, the findings from this study suggest that sex and dental status are important factors that can affect incisive canal characteristics and amount of bone anterior to the canal. Clinicians should perform careful planning using CT scans before performing dental implant surgeries in premaxillary region.     

Tooth position in full-mouth implant restorations--a case report

Reconstructing the edentulous mouth with opposing, fixed, implant-supported metal-ceramic restorations demands great attention to detail. This article reviews the basic principles of tooth position in dentate patients and in complete denture prosthodontics and relates them to the edentulous patient undergoing implant restoration. Determining gnathologic points and recognizing anatomic landmarks found in the edentulous jaws aid in correct tooth positioning, resulting in proper comfort, function, speech, esthetics, and a prearranged occlusal scheme, all of which are critical factors behind restorative-driven implant dentistry.     

Palatal size and shape in 6-year olds affected by hypohidrotic ectodermal dysplasia

OBJECTIVE: To analyze the size and shape of the hard tissue palate of Italian subjects with hypohidrotic ectodermal dysplasia (HED). MATERIALS AND METHODS: The morphology and the dimensions of the hard tissue palate were analyzed in eight 6-year-old boys affected by HED. Four of the boys were completely edentulous and four partially dentate. Palatal landmarks were identified on stone casts and digitized with three-dimensional computerized electromagnetic instrumentation. Palatal length, slope, width, and maximum palatal height in both the sagittal and frontal planes were measured. From the coordinates of palatal landmarks, a mathematical equation of palatal shape was constructed, independent of size. HED palatal data were compared with reference data obtained from 12 healthy boys with a complete deciduous dentition. RESULTS: Palatal length and height in both the sagittal and frontal planes were significantly reduced in HED as compared with control individuals. A less steep (not significant) palatal slope was found in HED than in reference subjects, whereas similar palatal width values were observed. All palatal measurements were larger in partially dentate than in edentulous patients. Both HED and edentulousness influenced palatal shape. The HED boys had a relatively lower palate than the reference boys. In the edentulous HED boys, the hard tissue palate was relatively lower than in partially dentate HED subjects. CONCLUSIONS: Palatal size and shape were significantly modified by the presence of hypohidrotic ectodermal dysplasia, and the major alterations were found in edentulous HED subjects.     

Three-dimensional force measurements on mandibular implants supporting overdentures.

The purpose of this study was to determine masticatory and functional forces in three axes on mandibular implants supporting overdentures. Five edentulous test subjects were selected, each having two mandibular implants. Three-dimensional piezoelectric force transducers were mounted on the two-part ITI Bonefit implants and rigidly connected to the denture. Forces in vertical, lateromedial, and anteroposterior directions were measured by means of electrostatic plotter records. The test modalities were light tapping, grinding, maximal occlusal force, and chewing test food. Results showed that the five subjects developed similar stress patterns but quantitatively different occlusal and chewing forces. In all but one subject, reduced maximal occlusal force was found compared to dentate subjects and edentulous subjects with fixed partial prostheses supported by implants. The recordings of chewing cycles when eating test food resulted in very regular rhythmic strokes, similar to those of dentate subjects but with slightly reduced speed. All stress patterns showed that occlusal and chewing forces were mainly directed in vertical, medial, and anterior dimensions. The dominating component was vertical.     

Three-dimensional hard tissue palatal size and shape in Down syndrome subjects

The aim of the present study was to evaluate palatal morphology in Down syndrome (Ds) subjects, focusing on the effect of dental formula on the hard palate to assist clinicians when planning dental rehabilitation. Palatal landmarks were digitized with a three-dimensional (3D) computerized digitizer on the dental casts of 47 Ds subjects (23 dentate males, 9 edentulous males, and 15 dentate females) aged 20-45 years, 37 dentate reference individuals (20 males and 17 females) aged 30-39 years, and 14 edentulous reference males aged 55-72 years. The co-ordinates of the palatal landmarks were used to construct a mathematical equation of palatal shape, independent of dimensions. Palatal length, slope, width, and maximum palatal height in both the sagittal and frontal planes were measured. In males, palatal length, width, and height were significantly influenced by both the syndrome and edentulism (analysis of variance, P < 0.05). The same measurements were significantly reduced in Ds compared with dentate females (t-test, P < 0.05). In the sagittal plane, Ds did not modify palatal shape; in the frontal plane, Ds individuals showed a higher palate. Overall, palatal shape was influenced by both Ds and edentulousness. Therefore, Ds seems to alter the normal palatal size and shape, although verification on larger samples is required. The findings of the present study may encourage more interdisciplinary dentofacial therapy in the dental and orthodontic care of Ds subjects.