Main occluding area in partially edentulous patients: changes before and after implant treatment

Masticatory performance with one missing molar

PURPOSE

This study aimed to evaluate masticatory performance in cases where one molar was missing.

METHODS

Participants were 156 adults with one molar missing from their natural teeth, who were divided into group A (without prosthetic treatment) and group B (with prosthetic treatment). The non-missing side was designated as A1 or B1, and the missing side was designated as A2 or B2. The amount of glucose eluted (AG) when the participants chewed a gummy jelly was measured and used as a parameter for masticatory performance. AG was compared between the non-missing side (A1, B1) and missing side (A2, B2), and between the first molar missing group and second molar missing group.

RESULTS

AG was significantly greater on the dentate side (P < 0.001) and was significantly less in the A2 group when the first molar was missing (P = 0.002). The rate of decrease of AG was 11.1%, 14.3%, and 8.4% in groups A+B, A, and B, respectively.

CONCLUSION

Masticatory performance appears to decrease even with only one missing molar. Although improvement is achieved by prosthetic treatment, performance remains inferior to that on the dentate side.

Impact of implant location on load distribution of implant-assisted removable partial dentures: a review of in vitro model and finite-element analysis studies

BACKGROUND

Appropriate load distribution among the supporting elements is essential for the long-term success of implant-assisted removable partial dentures; however, there is little information available on load distribution.

PURPOSE

This study aimed to evaluate the effect of implant location on load distribution in implant-assisted removable partial dentures by reviewing in vitro models and finite-element analysis studies.

MATERIALS AND METHODS

English-language studies which examined the load distribution of implant-assisted removable partial dentures and were published between January 2001 and October 2022 were extracted from PubMed, ScienceDirect, and Scopus online databases, and manual searching. Two reviewers selected the articles based on the predetermined inclusion and exclusion criteria, followed by data extraction and analysis.

RESULTS

Forty-seven studies were selected after evaluating the titles and abstracts of 264 articles; two were identified manually. After screening the text, 12 studies were included: six in vitro model experiments and six finite-element analysis studies. All included studies used a mandibular free-end missing model (Kennedy Class I or II). The influence of implant location on load distribution to the abutment tooth, implant, and mucosa under the denture base was summarized in three cases: implant at the premolar, first molar, and second molar region. Due to differences in the measurement method of load distribution and loading condition to the denture, the results differed among the studies.

CONCLUSIONS

The implant location in implant-assisted removable partial dentures can affect load distribution to the supporting elements, such as the abutment tooth, implant, and mucosa under the denture base.

A falta de dentição funcional está associada ao comprometimento das funções bucais entre adultos brasileiros

Resumo Objetivou-se identificar se a falta de dentição funcional (DF) está associada com o comprometimento das funções bucais/atividades diárias entre adultos brasileiros. Para isto, foram utilizados dados da Pesquisa Nacional de Saúde Bucal - SB Brasil 2010. A DF foi avaliada pelo critério proposto pela Organização Mundial de Saúde (pelo menos 20 dentes na boca). O instrumento Impactos Odontológicos nos Desempenhos Diários (IODD) foi utilizado para avaliar as atividades diárias/funções bucais. Análises descritivas, bivariadas (Qui-quadrado) e múltiplas (Regressão Logística) foram realizadas, sendo estimado o odds ratio e o intervalo de confiança 95% (OR/IC95%). Foram incluídos e avaliados 9564 adultos. Foram considerados sem DF 2200 adultos (20,5%). Tiveram impacto em pelo menos uma das atividades diárias/funções bucais avaliadas, 55,0% dos adultos. A falta de DF entre adultos foi associada (p ≤ 0,05) com o impacto na fala (1,88/1,33-2,64) e vergonha ao sorrir ou falar (1,35/1,00-1,83). Uma prevalência considerável de falta de DF foi identificada, esta ausência foi associada às atividades diárias/funções bucais (fala e vergonha ao sorrir e falar). A reabilitação dentária de pacientes sem DF deve considerar a devolução destas funções bucais perdidas (fala e vergonha ao sorrir ou falar).

Periodontal tactile sensation and occlusal loading condition of autotransplanted teeth: A retrospective pilot study

PURPOSE

The objectives of this retrospective pilot study were: (1) to examine the occlusal properties (periodontal tactile sensation, occlusal force support ability, dynamic tooth mobility, occlusal force, contact area, preferred chewing side and main occluding area) of autotransplanted teeth with no clinical complications after transplantation (postoperative periods from 1 to 7 years).

METHODS

Three groups were formed from 20 subjects (23 teeth in each group): autotransplanted teeth (ATP group), teeth contralateral to the recipient site (control group A), and teeth contralateral to the donor site (control group B).

RESULTS

The tactile detection threshold of the ATP group was higher than both the control groups, and the individual occlusal force was significantly lower than control group A. The occlusal force ratio and the occlusal contact area ratio were significantly lower in the ATP group than in both control groups, while the mobility was similar in all groups. Eight out of 20 subjects chose the autotransplanted teeth side as the preferred chewing side. Especially when the recipient site was the first molar, the ATP of these subjects were included in the main occluding area. The pocket depth of the three groups was within the normal range.

CONCLUSIONS

These results demonstrate that teeth autotransplantation can achieve a mastication efficiency and periodontal condition similar to normal teeth; however, without proper healing, the periodontal sensation of autotransplanted teeth may be inferior to that of normal teeth (<250).

Histological and radiographic study of human edentulous and dentulous maxilla

Data on the bone trabecular structure and density of the edentulous regions of the first upper molars are important for designing successful dental treatments, especially dental implants. However, no detailed defined morphometric properties on the human maxilla are available at the immunohistochemical and radiographic levels. Cone-beam computed tomography analysis and immunohistochemical observation were applied to the maxillary first molar region of 91 cadavers (46 males and 45 females). The edentulous maxilla can be classified into the following three forms: fully edentulous (FE), partially edentulous (PE), and immediately edentulous (IE). Compared with the first molar dentulous (FMD) specimens, significant differences in cortical bone structure and bone density exist among IE, PE, and FE in maxilla (P < 0.001). According to histochemical observations, the positive CD31 reaction clearly described a large vessel of the PE and small vessels of FMD and IE in maxillary sinus connective tissue. These structural issues were clearly related to tooth extraction. These morphological and radiographic data describing the edentulous region of the maxillary first molar might be useful for improving dental treatments.

The main occluding area in normal occlusion and mandibular prognathism

OBJECTIVE

To clarify whether the concept of main occluding area, where hard food is initially crushed, exists in patients who have a jaw deformity.

MATERIALS AND METHODS

Nineteen subjects with normal occlusion, 18 patients with mandibular prognathism, and 11 patients with mandibular prognathism who had undergone orthognathic surgery participated in this study. The main occluding area was identified by clenching Temporary Stopping. The coincidence, location of the main occluding area, and distance from the first molars to main occluding area were examined.

RESULTS

High coincidence of the main occluding area was obtained in all groups, signifying that the main occluding area exists even in these patients. Mandibular main occluding area was located on the first molar in all groups. Maxillary main occluding area in subjects with normal occlusion was located on the first molar. However, it was located on the second premolar and first molar in patients with mandibular prognathism, and on the first and second molars in patients with mandibular prognathism who had undergone orthognathic surgery. There was a statistically significant difference in distance from the maxillary first molar to the main occluding area among groups, but there was no difference in the distance from the mandibular first molar among groups.

CONCLUSION

The main occluding area is more stable on the mandibular first molar than the maxilla in all groups.

Comparative cross-sectional study of masticatory performance and mastication predominance for patients with missing posterior teeth

PURPOSE

Missing posterior teeth can decrease masticatory function and cause horizontal mastication deviation, i.e., mastication predominance. Mastication predominance may lead to abnormal tooth attrition and temporomandibular disorders. This study evaluated masticatory performance and mastication predominance in patients with missing posterior teeth to investigate effects of missing posterior teeth on masticatory performance and mastication predominance.

METHODS

Thirty volunteers with normal dentition (control group), 30 patients with unilateral missing posterior teeth (unilateral group), and 23 patients with bilateral missing posterior teeth (bilateral group) participated. Gummy jellies were used to evaluate participants' masticatory performance, and electromyography was used to assess the degree of mastication predominance. Chewing gums, gummy jellies, and peanuts were used as foods of various hardnesses for evaluating mastication predominance.

RESULTS

Compared with the control group, masticatory performance did not differ in the unilateral group but was significantly decreased in the bilateral group. With chewing gum and gummy jellies, the degree of mastication predominance was significantly increased in both unilateral and bilateral groups than the control group. With peanuts, the degree of mastication predominance was significantly increased in the unilateral group than the control group.

CONCLUSIONS

Although masticatory performance was not decreased in the unilateral group, the degree of mastication predominance was increased. Decreased masticatory performance was observed in the bilateral group, and for foods with normal hardness and soft foods, the degree of mastication predominance was increased. These results suggested that mastication predominance should be considered in the recovery of masticatory performance in patients with missing posterior teeth.

Effect of implant-supported prosthesis on the bite force and masticatory efficiency in subjects with shortened dental arches

The aim of the study was to assess changes in bite force and masticatory efficiency in shortened dental arch (SDA) subjects rehabilitated with implant-supported restoration for 1st molar. Ten SDA subjects with bilaterally missing mandibular molars (experimental group) were recruited. In each subject, one tapered threaded implant was placed bilaterally in 1st mandibular molar region and restored. Masticatory efficiency was evaluated objectively by measuring the released dye from chewed raw carrots, with a 'spectrophotometer' at 530 nm preoperatively and at 3 months after restoration. Bite force was evaluated using 'bite force measuring appliance' preoperatively, at 6 weeks and at 3 months after restoration. Ten completely dentate-matched subjects (in terms of age, sex, height and weight) acted as control. The results revealed that as compared with the control group, the experimental group showed significantly less (P < 0.05) mean maximum bite force at pre-restoration and at 6 weeks after restoration. Although at 3 months the mean maximum bite force value was less than the control group but the mean difference was statistically insignificant. The mean difference of masticatory efficiency between control and experimental group was statistically significant (P < 0.05) before restoration, but was statistically insignificant at 3 months after restoration. Thus it was concluded that after the restoration of mandibular arch with implant-supported prosthesis, both bite force and masticatory efficiency of all SDA subjects increased and were comparable to that of matched completely dentate subjects after 3 months.