Biomedical subjects

Chooi Gait Toh

Publications and source records attributed to Chooi Gait Toh.

6 recordsLinked to original sources

PubMed2005

Remaining tooth structure associated with various preparation designs for the endodontically treated maxillary second premolar.

Existing literature suggests a relationship between the amount of remaining tooth structure and the fracture resistance of the restored endodontically treated tooth. This study investigated the amount of tooth structure remaining following various tooth preparations used in the restoration of the endodontically treated maxillary second premolar. Illustrations of the maxillary second premolar in buccopalatal, mesiodistal and occlusal sections were drawn to scale. Outlines of various intra- and extracoronal preparations were superim-posed on the illustrations to reveal the amount of tooth tissue remaining in each case. Preparations for a ceramic inlay, inlay with palatal cusp coverage and onlay left 2.0-2.5mm of tooth structure buccally and palatally. Following preparation for a metal-ceramic crown, approximately 1.0mm of tooth structure remained buccally, and between 1.6mm-1.8mm palatally. Preparation for an all-ceramic crown was observed to leave 1.0mm-1.2mm of tooth structure surrounding what remained of the endodontic access cavity. It was concluded that decisions as to the type of definitive restoration to restore the endodontically treated maxillary second premolar may be influenced, amongst other factors, by information on the amount of tooth tissue remaining following preparation.

Bicuspid↗

PubMed2003

A survey of current practices among general dental practitioners in Manchester in 2002.

AIM: The purpose of this study was to obtain data on current approaches for the restoration of endodontically treated teeth among general dental practitioners (GDPs) in Manchester, United Kingdom. METHOD: A questionnaire containing 19 single-answer, multiple-choice type questions was mailed to 503 GDPs practising in the Greater Manchester area in January 2002. An explanatory covering letter and a stamped addressed return envelope were enclosed. The data obtained were processed using SPSS statistical software. RESULTS: Three hundred and fifty-one (70%) of the practitioners responded to the questionnaire. The restoration of root-filled teeth was normally undertaken within 1-2 weeks of completing root canal therapy by 63% of the practitioners. Only 35% of the GDPs used posts routinely in the restoration of root-filled anterior teeth; the corresponding figure for posterior teeth was 15%. While a cast, precious metal post was the preferred choice in the restoration of anterior teeth, the use of prefabricated posts and related techniques predominated in the restoration of posterior teeth. Composite resin was the most popular choice of material for core build-up procedures in anterior teeth. Amalgam tended to be favoured for core build-ups in posterior teeth. The majority of the practitioners (56%) routinely restored root-filled anterior teeth by means of porcelain-fused-to-metal crowns. Seventy-three per cent of the GDPs preferred to restore root-filled posterior teeth by means of a full veneer crown. CONCLUSIONS: The results of this study suggest that the practitioners surveyed had a sound understanding of the principles involved in the restoration of endodontically treated teeth, with the possible exception of the need to establish a durable coronal seal as soon as possible after the placement of a root filling.

England↗

PubMed2003

Bone-implant interface around titanium implants under different loading conditions: a histomorphometrical analysis in the Macaca fascicularis monkey.

BACKGROUND: Bone healing around endosseous dental implants is associated with peri-implant loading conditions. Therefore, the aim of this study was to evaluate histomorphometrically the bone response around unloaded, delayed, and immediately loaded implants with a progressive thread design that were placed in the posterior regions of the lower jaw in monkeys. METHODS: Nine adult monkeys (Macaca fascicularis) were used in this study. After extraction of the second premolars and first and second molars in the mandible, the bone was allowed to heal for a period of 3 months. Forty-eight 8 mm long implants with a diameter of 3.5 mm were placed according to the following protocol. In two of the monkeys, six implants were placed and left to heal submerged for 3 months (group A). In seven monkeys, 21 implants were placed in one side of the mandible and loaded after 3 months of submerged healing (group B). The group B implants were loaded with temporary resin bridges at the same time as another 21 implants that were loaded immediately (group C) after placement in the contralateral side of the mandibles of the same monkeys. The occlusion of group B and C implants was checked for optimal relationship of the resin bridges that were replaced 1 month later with metal bridges and loaded for an additional 2 months. The group A animals were sacrificed after 3 months of submerged healing without loading; group B and C animals were sacrificed after 3 months of implant loading. Specimens were examined histologically and histomorphometrically. RESULTS: All implants osseointegrated without presenting any gap in the metal-bone interface. Compact cortical bone was found in contact with the implant surfaces. Group A implants demonstrated in the interface cancellous bone with loose connective tissue. Group B and C implants showed a thick cortical plate with extensive bone trabeculae formation. There was a significant difference in bone-to-implant contact (BIC) between the various loading conditions. No significant difference (P < 0.05) was found between groups B and C. There was an increased area of bone (BA) within the threads as well as around the apices of group B and C implants. CONCLUSIONS: Implant loading might have stimulated increased bone formation and thus may be a key factor in influencing positive osseointegration. In addition, immediately loaded implants may osseointegrate in a similar manner as delayed loaded implants.

Animals↗

PubMed2003

Peri-implant soft tissue integration of immediately loaded implants in the posterior macaque mandible: a histomorphometric study.

BACKGROUND: Today, one critical goal in implant placement is the achievement of optimal soft tissue integration. Reports thus far have demonstrated successful soft tissue preservation in delayed loaded implants placed in anterior jaws. The aim of this study was to histomorphometrically examine the soft tissues around immediately loaded implants placed in the macaque posterior mandible. METHODS: Splinted crowns on screw-shaped titanium implants (8 mm length, 3.5 mm diameter) were utilized. Three implants each were placed in the premolar-molar edentulous mandibular segments of 6 adult monkeys (Macaca fascicularis); one side served as the control (delayed loading) and the other as the test sites (immediate loading). The animals were sacrificed after 3 months of loading. Histomorphometry of 6 soft tissue indices including the sulcus depth (SD), junctional epithelium (JE), connective tissue contact (CTC), biologic width (BW = SD + JE + CTC), DIM (distance between the implant top and coronal gingiva), and DIB (distance between the implant top and first implant-to-bone contact) was performed on non-decalcified sections. RESULTS: No significant differences in the mean soft tissue scores (mm) between the test (SD = 0.68 +/- 0.63; JE = 1.71 +/- 1.04; CTC = 1.51 +/- 1.14; DIM = 2.27 +/- 1.18; DIB = 1.32 +/- 1.21; BW = 3.9) and control (SD = 0.88 + 0.57; JE = 1.66 + 0.77; CTC = 1.24 +/- 0.92; DIM = 2.38 +/- 0.81; DIB = 1.19 +/- 0.91; BW = 3.78) groups were observed (P > 0.01). CONCLUSION: These findings suggest that the dimensions of the peri-implant soft tissues were within the biologic range and were not influenced by immediate functional loading or posterior location of the implants in the macaque mandible.

Alveolar Process↗

PubMed1999

A preliminary study of healing of superpulsed carbon dioxide laser incisions in the hard palate of monkeys.

BACKGROUND AND OBJECTIVE: Prior studies of laser wound healing using different animal models have shown a delayed tissue response after carbon dioxide (CO2) laser application. This article reports on the preliminary findings of healing of superpulsed CO2 laser and scalpel incisions in the hard palate of monkeys. STUDY DESIGN/MATERIALS AND METHODS: Twelve parallel incisions using a superpulsed, continuous wave CO2 laser and a scalpel were performed in the hard palate of each of two adult monkeys at 3, 7, and 14 days time schedules. Power levels of 2.0, 4.0, and 6.0 Watts were used for the laser incisions. Wounds were harvested, fixed in 10% formalsaline for at least 48 hours and processed routinely. Each specimen was embedded in paraffin wax at 90 degrees to the surface epithelium and 5 microm thick sections prepared for staining with haematoxylin and eosin, Periodic acid Schiff and Masson-trichrome at a step-serial interval of 100 microm. Sections were evaluated independently. RESULTS: According to the clinical findings we showed a wound closure in all of the wounds (laser and scalpel incisions) at 3, 7, and 14 days of healing. Histologically, we showed that laser incisions at three and seven days demonstrated an increased, power setting-dependent tissue necrosis and marked inflammatory response with minimal organization compared to scalpel incisions. At 14 days both types of incisions exhibited complete wound healing of the epithelium and connective tissue. DISCUSSION AND CONCLUSIONS: According to these preliminary results, superpulsed CO2 laser tends to produce more pronounced changes (due to tissue thermal damage) with corresponding greater inflammatory reaction and delay in tissue organization only initially.

Animals↗

PubMedDate not supplied

Histologic and histomorphometric evaluation of peri-implant bone subjected to immediate loading: an experimental study with Macaca fascicularis.

PURPOSE: Immediately loaded splinted implants can become osseointegrated when they are placed in the anterior part of the mandible. The concept of immediate loading has not been well examined in the posterior mandible. The aim of this study was to evaluate the hard tissue reactions around immediately loaded implants placed in the posterior mandible in the monkey model. MATERIALS AND METHODS: Six adult M. fascicularis monkeys were used in this study. Thirty-six Ankylos implants (Degussa Dental, Hanau-Wolfgang, Germany) were placed after extraction of the second premolar, first, and second molar teeth and complete healing of the sockets. Control (C) group implants were placed and, after osseointegration, were loaded for 1 month using temporary acrylic resin prostheses and later for 2 months using splinted metal crowns. In the contralateral region of the mandible, test (T) group implants were placed and loaded immediately with the same sequence as carried out for the C implants. After sacrifice of the animals, specimens were examined histologically and evaluated histomorphometrically. RESULTS: All implants were osseointegrated. Compact, cortical bone in contact with the implant surface without any gaps or connective tissue formation was demonstrated. DISCUSSION: Histomorphometric findings of the bone-implant-contacts showed no significant differences between the T and C group implants. Peri-implant mineralized bone areas presented statistically significant differences and showed a higher density of bone between the threads of immediately loaded implants (P < .05). CONCLUSIONS: Immediately loaded splinted implants in the posterior mandible can become osseointegrated with a hard tissue peri-implant response similar to that of delayed loaded implants. Moreover, immediate loading seems to increase the ossification of the alveolar bone around endosseous implants.

Alveolar Process↗