Proportion Of Teeth Research Articles

Esthetic proportions of maxillary anterior teeth of 120 Chinese adults

OBJECTIVE To analyze the esthetic proportions of maxillary anterior teeth in term of the apparent widths proportion of the adjacent teeth and width/height ratio of the clinical crown in 120 Chinese adults. METHODS Maxillary gypsum casts were obtained from the dental laboratories of stomatological hospitals in North China, Southeast China, and Southwest China, according to the inclusion criteria and exclusion criteria. Standardized digital photographs of each cast were recorded. The apparent widths and actual widths and heights of the central incisors, lateral incisors and canines were determined by ImageJ software for the calculation of apparent widths proportion of the adjacent teeth and width/height ratio of the clinical crown. The ideal apparent widths proportion (Golden proportion and Preston proportion) and width/height ratio (0.80) were tested. The gender, arch side, and regional differences were investigated. RESULTS The apparent widths proportion of the lateral/central incisor was 0.724±0.047, of the canine/lateral incisor was 0.814±0.092. The width/height ratio of the central incisor was 0.848±0.072, of the lateral incisor was 0.834±0.094, of the canine was 0.883±0.098. The esthetic proportions were different from the predicted ideal ratio (P < 0.001). The apparent widths proportion of lateral/central incisor was significantly larger in the right side than that in the left side (0.730± 0.044 vs. 0.718±0.050), and was significantly smaller in North China than that in Southwest China (0.711±0.051 vs. 0.731±0.044). The width/height ratio of the central incisor was significantly larger in the female than that in the male (0.855±0.074 vs. 0.835±0.068), and in the right side than that in the left side (0.855±0.073 vs. 0.842±0.072). The width/height ratio of the lateral incisor was significantly larger in the female than that in the male (0.843±0.097 vs. 0.817±0.084). CONCLUSION The apparent widths proportion of adjacent teeth and the width/height ratio of the clinical crown in Chinese adults are different from the foreigner's. The esthetic proportion parameters have significant population specificity, and the measurements cannot be generalized as well as it should be applied with caution.

Relationship between crown and root canal anatomy of four-rooted maxillary molar teeth.

This study aimed to determine the prevalence of four-rooted teeth and the corresponding crown, root and canal morphology in maxillary molars. Cone-beam computed tomographic images for 1200 patients were examined, and 1799 maxillary first molar (MFM) and 2123 maxillary second molar (MSM) teeth were evaluated. Statistical analyses were performed at a 5% significance level. Only three MFMs (0.17%) and 30 maxillary MSMs (1.41%) were four-rooted. The most common four-root type was the double palatal root. A higher proportion of four-rooted teeth were observed in men (P<0.05), and a high percentage of root fusion was seen in these teeth. The palatal half of the crown was wider in teeth with double palatal roots. Although rarely encountered, the diagnosis and proper treatment of these teeth are very important for endodontic success.

Association of periodontal disease with atherosclerosis in 70-year-old Japanese older adults.

Periodontal disease and arteriosclerotic disease are greatly affected by aging. In this study, the association of conventional risk factors and periodontal disease with atherosclerosis was longitudinally examined in Japanese older adults. Subjects in this study were 490 community-dwelling septuagenarians (69-71years) randomly recruited from the Basic Resident Registry of urban or rural areas in Japan. At the baseline examination, all subjects underwent socioeconomic and medical interviews; medical examinations, including examinations for carotid atherosclerosis, hypertension, diabetes mellitus, and dyslipidemia; and conventional dental examinations, including a tooth count and measurement of probing pocket depth (PPD). After 3years, 182 septuagenarians who had no atherosclerosis at the baseline examination were registered and received the same examination as at the baseline. In the re-examination conducted 3years after the baseline survey, 131 (72.0%) of the 182 participants who had no atherosclerosis at the baseline examination were diagnosed with carotid atherosclerosis. Adjusting and analyzing the mutual relationships of the conventional risk factors for atherosclerosis by multiple logistic regression analysis for the 171 septuagenarians with a full set of data, the proportion of teeth with PPD ≥ 4mm was independently related to the prevalence of atherosclerosis (odds ratio: 1.029, P < 0.022). This longitudinal study of Japanese older adults suggests that periodontal disease is associated with the onset/progression of atherosclerosis. Maintaining a healthy periodontal condition may be an important factor in preventing the development and progression of atherosclerosis.

Combination of Nonsurgical Endodontic and Vital Pulp Therapy for Management of Mature Permanent Mandibular Molar Teeth with Symptomatic Irreversible Pulpitis and Apical Periodontitis

IntroductionThis prospective study evaluated the outcome of a combination of nonsurgical endodontic (NSET) and vital pulp therapy (VPT) for the management of mature permanent mandibular molar teeth with symptomatic irreversible pulpitis (SIP) and apical periodontitis (AP). MethodsInstitutional ethical clearance was obtained. Mandibular molar teeth (N = 60) with a definitive diagnosis of SIP and AP with a radiographic periapical index score (PAI) of ≥3 in either 1 of the roots (mesial or distal) were included. Block randomization was used for allocation. In the NSET group (n = 30), single-visit NSET was performed using a standardized operating protocol. In the NSET-VPT group (n = 30), subsequent to full pulpotomy, at the root orifice where a vital pulp was observed (as determined by the arrest of pulpal bleed upon application of a 2.5% sodium hypochlorite pressure pack), a mineral trioxide aggregate radicular barrier was placed, and it was covered with light-cured resin-modified glass ionomer cement. NSET was performed in the root exhibiting a PAI score ≥3. The tooth was permanently restored. Postoperative pain was assessed at 24, 48, and 72 hours. Teeth were followed up clinically and radiographically at 12 months. The presence/absence of symptoms and the change in PAI scores were noted. The data were statistically analyzed. ResultsThe success rate was 90% in the NSET group and 93.3% in the NSET-VPT group. According to an intergroup comparison between the proportion of teeth healed and nonhealed (radiographic), there was no significant difference (P > .05). ConclusionsThe combination of NSET and VPT is a viable biologically based minimally invasive treatment option for multirooted mandibular teeth with SIP and AP.

Self-Reported Oral Health, Oral Hygiene and Associated Factors in Lithuanian Adult Population, 1994-2014.

This study aimed to examine 20-year trends (1994–2014) in self-reported oral health and oral hygiene and to assess the associated factors in a Lithuanian population aged 20–64 years. Nationally representative cross-sectional data on 8612 men and 11,719 women were obtained from 11 biennial postal surveys of Lithuanian health behavior monitoring. Dentate status was assessed by asking about the number of missing teeth. Over the study period, the proportion of men with all teeth increased from 17.5% to 23.0% and the same proportion increased in women—from 12.5% to 19.6%. The prevalence of edentulousness was 2.8% in 2014. The proportion of individuals brushing teeth at least twice a day increased from 14.6% to 31.9% in men and from 33.0% to 58.8% in women. Multivariate logistic regression analysis revealed that older age, lower education, living in rural areas, daily smoking, confectionary consumption (only in women), obesity, no visits to a dentist during the past year, toothache and brushing teeth less than twice a day increased the odds of missing six or more teeth. Efforts should be made to promote good oral hygiene habits, prevent and control behavioral risk factors and increase access to dental care among risk groups.

GOLDEN PROPORTION GIGI INICISIVUS SENTRAL RAHANG ATAS SUKU BALI DI FAKULTAS KEDOKTERAN GIGI UNIVERSITAS MAHASARASWATI DENPASAR

Tooth size determines a person's aesthetics. Some guidelines that can help in determining the size of the maxillary anterior teeth are pre-extraction instructions such as facial photographs, diagnostic models, radiographic photographs, and extracted teeth. &nbsp;If the instructions before extraction are not obtained then an ideal proportionis needed. This study aims to determine whether or not thereis a relationship between the width and high of the face to the mesiodistal and cervico incisal of the maxillary central incisors and what is the proportion of these teeth. &nbsp;This research is a analytic observasional research with design of crosssectional, &nbsp;using samples of 47 subjects from Bali'sTrobe age 17_25 at Facultyof Dentistry in Unmas Denpasar. The resul to research show a significant correlation between face width and high to the size of mesiodistal and servico incisal of the maxillary centralincisorson Bali'sTrobe. The proportion of face and teeth of Balinese belonging to the Mongoloid race was obtain 1 :1,639 and mesiodistal and cervicoincisal of the maxillary central incisors where1 : 1,6409

Interdisciplinary approach using composite resin and ceramic veneers to manage an esthetic challenge

This clinical report describes the management of an esthetic challenge in an interdisciplinary manner addressing both the soft tissue and the anterior dentition. Different restorative materials were used in an esthetic and conservative manner to provide a pleasing smile. A minimally invasive approach was adopted to manage the anterior esthetics problems, including a maxillary diastema and inadequate width-to-length tooth proportions.

Evaluation of Enamel Topography after Debonding Orthodontic Ceramic Brackets by Different Er,Cr:YSGG and Er:YAG Lasers Settings.

In the last decade, the success of lasers in simplifying many dental procedures has heightened the need for research in the orthodontic field, in order to evaluate the benefits of laser-assisted ceramic brackets debonding. Conventional ceramic brackets removal delivers a high shear bond strength (SBS), which might lead to enamel damage. Nowadays, debonding ceramic brackets by Er:YAG laser seems a viable alternative technique; however, there is no data on the use of Er,Cr:YSGG in the literature. We aimed to evaluate the difference in enamel topography derived from different erbium laser settings used during debonding. One hundred and eighty bovine incisors teeth were randomly divided into fifteen experimental groups, according to different erbium laser settings using scanning methods. SBS testing was performed after debonding; stereomicroscopic and SEM analyses were done after cleaning the remaining adhesive so as to assess the incidence of enamel microcracks formation and enamel loss. There were no statistically significant differences between the proportions of teeth with normal enamel topography within the control group when compared with any of the Er:YAG groups. However, the proportion of teeth with a normal enamel topography in Er,Cr:YSGG was 4 W/20 Hz (83.3%) and in Er:YAG was 5 W/20 Hz (91.7%), which was statistically significantly higher than the control group (41.7%). The selection of erbium lasers’ optimal parameters during debonding influences the enamel topography. When considering the evaluation of both microscopic and statistical analyses, irradiation by Er:YAG (120 mJ/40 Hz) displayed a significant reduction in microcracks compared with conventional debonding, even though some microstructural changes in the enamel could be noted. Er,Cr:YSGG (4 W/20 Hz) respected the enamel topography the most out of the studied groups.

A stepwise approach to the correction of excessive gingival display: an integrative review of the literature

Abstract Background Excessive gingival display is an aesthetic concern for patients and a challenge for clinicians. An accurate diagnosis is essential in order to provide effective treatment. Aim The aim of the present article is to fill a gap in the current literature by providing clinicians with an overview and a stepwise approach to assessing gingival excess, as well as reviewing possible treatment. Method Published articles related to smile aesthetics and excessive gingival display over the last 40 years were identified and analysed through an electronic search. Results An examination should be initiated extra-orally to distinguish contributing skeletal factors. The relationships of four aesthetic parameters (LIPG): lip length (L), incisal lines (I), tooth proportions (P), and gingival lines (G), should be examined individually to determine other possible causes of gingival excess. Contributing factors may include a short or hypermobile upper lip, dentoalveolar extrusion, or altered passive eruption. Further investigation to identify patients who might benefit from orthognathic surgery, orthodontic treatment alone, lip repositioning or botulinum injection, or aesthetic crown lengthening procedures, should be conducted to reconfirm a diagnosis and provide the optimal treatment. Conclusion Clinicians can have a dental blueprint for anterior tooth reconstruction and are able to provide comprehensive treatment in co-operation with other disciplines. By understanding the principles of an aesthetic smile line, the aetiology of an excessive gingival display and treatment concepts, clinicians may provide alternative treatments to avoid extensive surgical procedures while achieving acceptable outcomes.

Cirurgia de aumento de coroa clínica e confecção de facetas diretas em resina composta orientadas por mock-up.

Keeping in mind the final result is the basis of any type of treatment, especially those in which the morphology, size and proportion of the anterior teeth will be changed. This is where a good treatment plan based on a diagnostic wax-up tested with a mock-up and approved by the patient becomes crucial. This case report aims to exemplify how to transfer the diagnostic information to the patient’s mouth and direct it not only to the restorative dentistry, but also to the surgeon when performing the crown length. Diagnostic waxing was performed by the laboratory technician, obeying anterior posterior incisal and gingival criteria and curvatures, which were transported to an aesthetic guide through mock up to mark the surgical points. Then, surgery to increase the clinical crown with bone access and after healing, direct venners in composite resin also guided by waxing. In conclusion, a workflow can be established using the wax-up / mock-up that serves as a guide for the periodontist in the approach to surgical lengthening of the crown and for the rehabilitator who uses it to produce changes in the shape of dental dimensions .

PROA concept: prosthetic restoration with orthodontic appliance.

This paper describes an alternative computer-aided design/computer-aided manufacturing (CAD/CAM) technique for the creation of a combined prosthetic restoration with orthodontic appliance (PROA). This concept allows the use of orthodontic appliances such as brackets, attachments, or any other type of appliance over different types of prosthetic restorations. The PROA concept aims to mitigate problems associated with performing restorative treatment when orthodontic treatment is necessary. This proposed concept provides the clinicians with proper control and planning of the interdisciplinary treatment that will lead to the final tooth shape, form, and proportions while performing orthodontic tooth movements.

Solutions for atypical problems in the incisors area: a transdisciplinary challenge

ABSTRACT Introduction: A significant increase in the number of adults in search of orthodontic treatment has raised a new challenge for orthodontists: the need to interact with other specialties to achieve excellent results, particularly when dealing with smile aesthetics and facial balance. Several factors should be considered to respond to their demand: adequate tooth leveling and alignment, individual tooth proportions between adjacent teeth and their contralateral teeth, shape and natural appearance of each tooth and gingival architecture, which should all be in agreement with facial harmony. Maxillary or mandibular incisors congenitally missing or lost due to caries or trauma and tooth-size discrepancies (Bolton) are some of the important aesthetic challenges for an integrated orthodontic treatment. Objectives: This study describes cases that illustrate the clinical challenges of treating the anterior area, as well as the multidisciplinary strategies required for their resolution. Conclusion: The increasingly frequent multidisciplinary orthodontic treatments of complex cases seem to effectively maximize aesthetic and functional results using a combination of procedures conducted by specialists in related areas, such as Surgery, Prosthetics, Implantology, Restorative Dentistry and Periodontics.

A Case Report on Aesthetic Rehabilitation of Midline Diastema- An Insight into Perio-Restorative Interrelationship

Aesthetic restorative procedures have gained immense popularity in the recent years. Midline diastemas have been commonly reported by a majority of patients due to poor aesthetic appeal. Various treatment modalities are available and cases have to be managed differently depending on the aetiological factors. Also, the selection of an appropriate restorative option is imperative to providing a pleasing smile. Conservative treatments that provide a solution to aesthetic problems and fulfil the patient’s expectations should always be the first therapeutic option. Ceramic veneers are capable of providing an accurate replica of the natural teeth along with good colour stability and periodontal biocompatibility. Soft tissues play a vital role in creating a harmonious and aesthetic result between the restorations, hard tissues and surrounding gingiva. Therefore, periodontal treatments such as crown lengthening and frenectomy are essential for creating an ideal soft tissue form corresponding to the tooth proportions. Management of large anterior interdental spaces requires a comprehensive treatment planning and often, a multidisciplinary approach is essential from a team of restorative dentists and periodontists to focus on the aetiological factors, patient needs, aesthetics and achieve stable long-term clinical results. The present case report discussed the satisfactory management of a wide anterior maxillary midline diastema in a 30-year-old female using a conservative perio-restorative approach with ceramic veneers after frenectomy and aesthetic crown lengthening procedure without any orthodontic intervention. The success of the present case was determined by a proper diagnosis of the underlying aetiology, treatment planning, use of ceramic veneers and total-etch adhesive technique.

The art of minimal tooth reduction for veneer restorations

AbstractMinimal tooth reduction is crucial for the long-term success of adhesive restorations. It has been proven that bonding to enamel is more predictable in obtaining better long-term success than dentin due to its higher percentage of mineral content. The diagnostic wax-up and subsequent mock-up are the first diagnostic tools available to evaluate discrepancies between current and ideal tooth proportions. The intraoral mock-up provides the patient a tactile and visual evaluation of the size, shape, and shade of the proposed final restorations, and at the same time, the clinician can evaluate the smile line, lip support, phonetics, and occlusion. During the tooth preparation, the mock-up provides a reduction guide to the clinician to achieve the minimal required reduction for the final restoration avoiding the over-reduction and dentin exposure. This clinical report shows feldspathic veneer restorations provided with conservative tooth preparation. The long-term success of the restoration requires following well-defined protocols for restorative material selection, conservative tooth preparation, total isolation with rubber dam, and bonding ceramic protocols.

Conservative Ultrathin Veneer Restorations with Minimal Reduction: A 5-year Follow-up Report

This case report shows how a feldspathic veneer with diagnostic wax-ups, subsequent mock-up, and reduction guides can lead to good patient esthetics and reports a 5-year follow-up. Conservative tooth preparation is important for the long-term success of adhesive dentistry as it has been shown that bonding to enamel is more predictable in obtaining better long-term success than dentin. To preserve enamel for optimal bonding, diagnostic wax-ups and the subsequent mock-up are the first tools in a restorative dentist's arsenal to find and address differences between current and ideal tooth proportions and also help toward an overall conservative approach. Reduction guides are recommended in order to provide adequate tooth reduction and prevent over-reduction. This case report shows a 5-year follow-up of feldspathic veneer restorations for a patient with excessive space among teeth, defective composite restorations on facial and incisal surfaces, and worn teeth. Veneers were delivered with conservative tooth preparation combining different tooth reduction guides. This case report highlights the added benefits of tooth reduction guides and diagnostic wax-ups and the subsequent mock-up for long-term patient satisfaction. Conservative tooth preparation, reduction guides, and wax-ups may increase the life span of veneer restorations and demonstrate good esthetics at 5 years.

Age-Specific Predictive Models of the Upper Quintile of Periodontal Attachment Loss

A practical method to identify people who are most affected by periodontitis in their age group is currently unavailable. We focused on individuals with mean clinical attachment loss (CAL) above the 80th percentile within each of 10 age groups (5-y intervals between 30 and 74 y as well as ≥75 y). We developed predictive models using combined data from 2 cohorts (2009 to 2010 and 2011 to 2012) from the NHANES (National Health and Nutrition Examination Survey; development cohort [DC], n = 6,757), and we carried out external validation using data from a third NHANES cohort (2013 to 2014; validation cohort [VC], n = 3,447). We used 1) age-specific logistic regression models with stepwise selection to identify significant demographic variables, habits, medical conditions, and selected clinical periodontal parameters (proportion of teeth with probing depth ≥4 mm at incisors and molars and with visible [≥2 mm] recession) and to calculate propensity scores (PSs); 2) Youden’s J statistic to select optimum PS cutoffs to maximize diagnostic performance using receiver operating characteristic curves; and 3) bootstrap resampling with 1,000 replicates to validate the age-specific models and adjust the PS and optimal PS cutoffs for overfitting. The bootstrap-adjusted PSs were used as single predictors of mean CAL over the 80th percentile in the VC. The age-specific upper quintiles of mean CAL ranged between 1.63 and 3.24 mm in the DC and between 1.87 and 3.20 mm in the VC. The area under the curve of the models exceeded 0.85 in all age groups in the DC and 0.84 in the VC, indicating well-validated diagnostic performance. In the DC, sensitivity values ranged between 0.75 and 0.97 and exceeded 0.83 in 8 of 10 age groups. Corresponding values in the VC ranged between 0.56 and 0.89 and exceeded 0.68 in 8 of 10 age groups. We conclude that modeling that incorporates readily obtainable variables through a brief patient interview and an abbreviated periodontal examination accurately identifies individuals who are most affected by periodontitis in different ages.

Clinical and Esthetical Evaluation of 79 Lithium Disilicate Multilayered Anterior Veneers with a Medium Follow-Up of 3 Years.

Objectives Primary aim of this study was to evaluate survival rate of lithium disilicate veneers in upper and lower anterior teeth. Secondary aims were to evaluate changing in proportions of teeth before and after restorations and to assess mean thickness of the veneers. Materials and Methods Seventy-nine upper and lower lithium disilicate veneers were made in 13 patients with worn teeth. Mean follow-up was 3 years. To perform anterior definitive rehabilitations, malocclusions and loss of vertical dimension were treated by full mouth rehabilitations to obtain proper occlusal conditions. Veneers were made of lithium disilicate core and fluorapatite-based ceramic stratification. Survival rate was calculated by Kaplan–Meier analysis. Changing in teeth proportion before and after restorations was analyzed by a paired t -test. Descriptive statistics of thickness values were also performed. Results One case of detachment was observed with a 98.7% survival rate. Teeth’s proportions were preserved although the first upper right incisor and canine changed in dimension. Conclusions Lithium disilicate veneers in esthetical rehabilitations of worn teeth proved to be an effective way of treatment in a medium follow-up of 3 years. Proportions seemed to be maintained with a minimum dental removal.

Morphometric comparison of Panthera spelaea (Goldfuss, 1810) from Poland with the lion remains from Eurasia over the last 700 ka

The Pleistocene lion Panthera spelaea was not a homogenous taxon; it was represented by three chronoforms. The oldest one, from the Early and Middle Pleistocene, was P. s. fossilis, the youngest was the Late Pleistocene cave lion P. s. spelaea. The intermediate form between them was P. s. intermedia. The scarcity of stratigraphically old lion made it difficult to understand the evolution of this carnivore. Therefore, we revised the fossil material of the Pleistocene lion from Polish excavation sites. The analysis revealed the presence of P. s. fossilis in 7 sites: Tunel Wielki, Południowa, Wschodnia, Draby, Biśnik, Deszczowa and Wierzchowska Górna caves. The remains from these localities significantly differed in their average size and teeth proportions from the nominate younger chronoform, i.e. the cave lion. Using this material and all other available data, we compared the lion remains grouped into four palaeoclimate periods: MIS 17-12, MIS 11-9, MIS 8-6 and MIS 5-2. We found significant time-related trends in many morphometric features of dentition and limb bones. Between the first two periods, the lion became larger but from MIS 8, it gradually decreased in size. The teeth showed a much greater rate of changes than the metapodial bones, which in turn were characterised by more heterogeneous and mosaic evolution. The changes observed in the fossil material can result from in situ evolution of lion populations occupying Europe or immigration and replacement of the native forms by those from other regions, for example Asia.

Longitudinal evaluation of periodontitis and tooth loss among older adults.

To evaluate pattern of change in periodontal variables and tooth loss in a twelve-year follow-up study of older adults living in Sweden. In a prospective population study of older adults, a clinical examination and radiographic dental examination were performed at baseline (2001-2003) and after 12years (2013-2015). In 375 individuals, the number and proportion of sites with a distance ≥4mm and ≥5mm from cemento-enamel junction to the bone level, the number and proportion of teeth with pockets ≥5mm and number of teeth lost were calculated. Dental caries was registered. Periodontitis was defined as having ≥2 sites with ≥5mm distance from cemento-enamel junction to the marginal bone level and ≥1 tooth with pockets ≥5mm. A diagnosis of periodontitis was evident in 39% of the individuals, and 23% of the individuals lost ≥3 teeth over the study period. The proportion of sites with ≥4mm and ≥5mm bone loss increased with age, while the proportion of teeth with pockets remained stable. Periodontitis was the strongest predictor for losing ≥3 teeth, OR 2.9 (p<.001) in the final model. Periodontitis is a risk factor for future tooth loss among older adults.

A diminutive Pliocene guenon from Kanapoi, West Turkana, Kenya

Although modern guenons are diverse and abundant in Africa, the fossil record of this group is surprisingly sparse. In 2012 the West Turkana Paleo Project team recovered two associated molar teeth of a small primate from the Pliocene site of Kanapoi, West Turkana, Kenya. The teeth are bilophodont and the third molar lacks a hypoconulid, which is diagnostic for Cercopithecini. The teeth are the same size as those of extant Miopithecus, which is thought to be a dwarfed guenon, as well as a partial mandible preserving two worn teeth, previously recovered from Koobi Fora, Kenya, which was also tentatively identified as a guenon possibly allied with Miopithecus. Tooth size and proportions, as well as analysis of relative cusp size and shearing crest development clearly separate the fossil from all known guenons. Based on the Kanapoi material, we erect a new genus and species, Nanopithecus browni gen. et sp. nov. The small size of the specimen suggests either that dwarfing occurred early in the lineage, or at least twice independently, depending on the relationship of the new species with extant Miopithecus. Further, the distinctive habitat and geographic separation from Miopithecus suggests that the origin of small body size is not uniquely linked to the current habitat of Miopithecus, and possibly that relatives of extant Miopithecus were much more widely distributed in the past. This in turn argues caution in using extant biogeography in models of the origins of at least some guenons.